Profile angle

The profile angle of a gear is the angle at a specified pitch point between a line tangent to a tooth surface and the line normal to the pitch surface (which is a radial line of a pitch circle). This definition is applicable to every type of gear for which a pitch surface can be defined. The profile angle gives the direction of the tangent to a tooth profile.
In spur gears and straight bevel gears, tooth profiles are considered only in a transverse plane, and the general terms profile angle and pressure angle are customarily used rather than transverse profile angle and transverse pressure angle. In helical teeth, the profiles may be considered in different planes, and in specifications it is essential to use terms that indicate the direction of the plane in which the profile angle or the pressure angle lies, such as transverse profile angle, normal pressure angle, axial profile angle.
Types.
Standard.
In tools for cutting, grinding, and gaging gear teeth, the profile angle is the angle between a cutting edge or a cutting surface, and some principal direction such as that of a shank, an axis, or a plane of rotation.
Standard profile angles are established in connection with standard proportions of gear teeth and standard gear cutting tools. Involute gears operate together correctly after a change of center distance, and gears designed for a different center distance can be generated correctly by standard tools. A change of center distance is accomplished by changes in operating values for pitch diameter, circular pitch, diametral pitch, pressure angle, and tooth thicknesses or backlash. The same involute gear may be used under conditions that change its operating pitch diameter and pressure angle. Unless there is a good reason for doing otherwise, it is practical to consider that the pitch and the profile angle of a single gear correspond to the pitch and the profile angle of the hob or cutter used to generate its teeth.
Transverse.
The transverse pressure angle and transverse profile angle are the pressure angle and the profile angle in a transverse plane.
Normal.
Normal pressure angle and normal profile angle are the pressure and profile angles in a normal plane of a helical or a spiral tooth. In a spiral bevel gear, unless otherwise specified, profile angle means normal profile angle at the mean cone distance.
Axial.
Axial pressure angle and axial profile angle are the pressure angle and the profile angle in an axial plane of a helical gear or a worm, or of a spiral bevel gear.


Thin-wall injection molding

Thin wall injection molding is a specialized form of conventional injection molding that focuses on mass-producing plastic parts that are thin and light so that material cost savings can be made and cycle times can be as short as possible. Shorter cycle times means higher productivity and lower costs per part.
The definition of thin wall is really about the size of the part compared to its wall thickness. For any particular plastic part, as the wall thickness reduces the harder it is to manufacture using the injection molding process. The size of a part puts a limit on how thin the wall thickness can be. For packaging containers thin wall means wall thicknesses that are less than 0.025 inch (0.62mm) with a flow length to wall thickness greater than 200.
Markets.
The trend towards thin wall molding continues to increase in many plastic industries as plastic material and energy costs continue to rise and delivery lead times are squeezed.
The following industries make use of thin wall molding:
Examples.
Plastic resins suitable for thin-wall molding should have high-flow properties, particularly low melt viscosity. In addition, they need to be robust enough to avoid degradation from the heat generated by high shear rates (high injection speeds)
Some plastic manufacturers make plastics specifically for thin wall applications that have excellent flow properties inside the mold cavity. For example, plastic manufacturer Sabic has a polypropylene food contact grade plastic which is specifically designed for thin wall margarine containers and lids.
Another plastic manufacturer, Bayer, makes a blend of Polycarbonate (PC) and Acrylonitrile butadiene styrene (ABS) specifically designed to make thin wall mobile housings.
Equipment.
Plastic injection molding machine.
Compared to conventional injection molding, thin wall molding requires molding machines that are designed and built to withstand higher stresses and injection pressures. The molding machines computer control should also be precise in order to make quality parts. For this reason these molding machines are more expensive than general purpose machines.
Thin-wall-capable machines usually also have accumulator-assisted clamps to accommodate fast cycle times.
Regular maintenance schedules must be completed so that the machine and part quality does not suffer. These machines usually work 24/7 so they need to be well maintained.
Injection mold design.
As with the injection molding machines, injection molds need to be robust enough to withstand high stresses and pressures. Heavy mold construction with through hardened tool steels will ensure a long lasting mold.
The mold must also have a well designed cooling system so that heat can be quickly extracted from the hot plastic part allowing fast cycle times. To achieve this, cooling channels need to be designed close to the molding surface.
Cleaning the mould on a daily basis is also a critical requirement to maintain the part quality.
Robotics.
In countries where manual labour is expensive, robots are commonly used to remove the plastic parts from the mold and order them into equal stacks. These robots are fixed to the molding machine and need to be fast and reliable.
Plastic injection molding process.
The range of process parameters, which are employed for thin wall molded parts, is considerably narrower than that of conventional injection molding because thin parts are difficult for the injection unit of the machine to fill compared to thicker parts. Even with optimally designed parts and molds, it is still more difficult to produce parts with thin walls.
Consistent injection speeds and pressures are required to maintain the quality of the parts produced from thin wall molding. A properly trained molding technician who understands and operates the machine within the confines of the narrow processing window at which the molded product's production cost-effectiveness is optimized will ensure that the process produces quality parts during the production.


Parallels (engineering)

Parallels are rectangular blocks of metal, commonly made from tool steel, stainless steel or cast iron, which have 2, 4 or 6 faces ground or lapped to a precise surface finish. They are used when machining with a mill, drill or any other machining operation that requires work to be held in a vise or with clamps - to keep work parallel or raised evenly such as in a milling vise to give adequate height for the cutting tool/spindle to pass over.
Description.
Parallels come in pairs of two, which are machined to be the same dimensions as their corresponding faces. They come in a variety of thicknesses and size, allowing them to be stacked up or to support a workpiece which doesn't have a flat profile. Parallels commonly have a series of holes drilled on the 'front' face - allowing them to be used to position a workpiece or secured using t-slot clamps, and a countersink on each side to remove any sharp edges.
Generally, workshop parallels have 4 faces that are machined and ground - the front, back and sides, although some do have the ends with a smooth surface. The surface of a parallel can often tell how it was manufactured, with a 'grain' showing that it was ground - and a smooth or mirrored finish showing it has been lapped. Parallels that have a good surface tolerance can be lightly bonded together by sliding or rotating two parallels together, and the smooth surfaces allows a temporary molecular-attraction to take place - this is known as Wringing and is also found with gauge blocks.
Manufacturing.
There are two main grades of surface tolerance:
Parallels are first machined to rough dimensions, leaving a few millimeters to allow the rest to be ground. Parallels that only have 2 or 4 precision faces will often have the tool-marks from the machining on the non-ground sides. They are then paired and placed in a grinding machine, and each face is ground until the overall dimensions are correct - they are paired during this stage so that even if the dimensions are not correct, they are still parallel to each other. Then, the individual finishes are applied, from drilling to machining a chamfer along the edges to remove any burrs or sharpened edges. They may also be lapped to achieve a mirror smooth surface. Most parallels are also hardened.
Parallels are manufactured to either imperial or metric dimensions, and are often sold in a set, with several pairs of different sizes.
Uses.
Parallels are used in machining operations, be it milling, drilling, turning or sometimes grinding. The most common use is to support work when it is in a vise or clamped to the machine bed. If a workpiece is too small to be machined in a vise without it being in contact with all three faces of the vice - parallels can be used either side to give clearance from the vise, and to give support from underneath to eliminate the workpiece being pushed down by the force of the cutting tool.
Parallels of different sizes can be used to support a workpiece that doesn't have a 'flat' surface underneath, or to give clearance when drilling in a vise to stop the drill damaging the vise. Parallels can also be used if the vise itself has a damaged face, which could cause the workpiece to be held insecurely.
Other uses include giving a raised surface when using t-slot clamps and for comparison with a surface or machined face to check the flatness.


Graping

Graping is a phenomenon marked by the appearance of unreflowed solder particles on top of the solder mass. The solder that is partially coalesced looks like a cluster of grapes which is where the phenomenon’s name is derived.
Causes.
Graping occurrence has continued to increase since it was first identified in 2006. The viscosity of the flux decreases as the temperature of the reflow oven increases. Lead-free reflow soldering temperatures are higher which results in more graping. Graping is also caused by increased surface oxidation. The increased surface oxidation is the result of smaller printed paste deposit volumes that cause a diminished surface area to flux ratio of the solder particle resulting in flux exhaustion. While solder paste can be manufactured using any size range, there has been a move towards finer particle sizes, especially for fine feature stencil printing. Finer particle sizes places added pressure on the solder paste flux to remove surface oxides which leaves the outside of the joint not fully coalesced producing the irregular surface finish known as graping.
Resolutions.
The graping phenomenon can be resolved utilizing proper solder materials in addition to correct reflow profile settings. Solder powders are available that provide a tighter distribution range as well as a high oxidation barrier. This barrier not only improves the paste release from the stencil, but also provides an ideal surface area-to-volume ratio. These solder powder characteristics help to eliminate the graping phenomenon. Future solder paste flux formulations provide sufficient activity paired with re-oxidation mitigation capabilities. This pairing means that graping can be resolved as it occurs which is ideal for miniaturization processes.
There are also steps to take when setting up your reflow profile to reduce the amount of heat exposure to the solder paste during the reflow process and prevent graping.


Annealed pyrolytic graphite

Annealed Pyrolytic Graphite (APG), also known as Thermally Annealed Pyrolytic Graphite (TPG), is a form of synthetic graphite that offers excellent in-plane thermal conductivity. As with pyrolytic carbon or pyrolytic graphite (PG), APG is also low in mass, is electrically conductive, and offers diamagnetic properties that allow it to levitate in magnetic fields.
Physical Properties.
APG is an anisotropic material with extremely high in-plane thermal conductivity (1,700 W/m-K at room temperature ) and low through-thickness conductivity. Its laminate structure remains stable across a wide temperature range allowing it to be used in a variety of heat transfer applications. APG's conductivity generally increases as the temperature decreases, peaking at 2,800 W/m-K at approximately 150 K. Unlike pyrolytic graphite, the x-y planar conductivity is consistent across each basal plane, thus the conductivity in the center planes is consistent with the outer planes. The in-plane covalently bonded carbon atoms in a hexagonal geometry account for APG's high in-plane thermal conductivity and its high in-plane stiffness. Through its thickness, these hexagonal planes are weakly bonded (van der Waals bonds) resulting in a material with poor through-thickness thermal conductivity, stiffness, and strength.
Synthesis.
APG is produced in a process similar method to Highly Oriented Pyrolytic Graphite (HOPG), where hydrocarbon gas is heated until it breaks down into carbon. Pyrolytic graphite (PG) is then grown on plates using a chemical vapor deposition (CVD) process. The PG is then annealed at high temperature to form the more planar and more uniform carbon structure of APG, described above. The primary difference between the HOPG and APG synthesis methods is that the APG annealing process does not require the use of induced stresses, resulting in a more affordable and practical bulk material for production use.
Applications.
APG is primarily used as a heat spreader for the thermal management of high-end electronics. Due to its poor mechanical properties APG is typically encapsulated within in structural metallic materials. Aluminum is the most commonly chosen encapsulant for its strength, low mass, cost, manufacturability, and thermal conductivity. Since APG's conductivity is much lower through its thickness, thermal vias are sometimes inserted into the assembly to transfer heat into the graphite, as shown in Figure 1. These vias are typically composed of aluminum or copper. Thin, flexible sheets of APG can be encapsulated in thin flexible materials, such as polymers, aluminum foil, or copper foil to create what is known as a Thermal Strap.
Aerospace: Aluminum-APG plates are most commonly used as heat spreader plates to transfer heat away from high power density electronics in aircraft and spacecraft.
Scientific Cameras: Cu-APG plates are used to cool and isothermalize CCD detectors at cryogenic temperatures.


Grinding wheel wear

Grinding wheel wear is an important measured factor of grinding in the manufacturing process of engineered parts and tools. Grinding involves the removal process of material and modifying the surface of a workpiece to some desired finish which might otherwise be unachievable through conventional machining processes. The grinding process itself has been compared to machining operations which employ multipoint cutting tools. The abrasive grains which make up the entire geometry of wheel act as independent small cutting tools. The quality, characteristics, and rate of grinding wheel wear can be affected by contributions of the characteristics of the material of the workpiece, the temperature increase of the workpiece, and the rate of wear of the grinding wheel itself. Moderate wear rate allows for more consistent material size. Maintaining stable grinding forces is preferred rather than high wheel wear rate which can decrease the effectiveness of material removal from the workpiece.
Mechanisms of wheel wear.
A common attributing factor to wheel wear is grain fracture, which can be an advantage. A portion of each of the individual grains on the wheel surface breaks apart and leaves the remaining grain bonded to the wheel. The fractured grain is left with newly exposed sharp edges which attribute the self-sharpening characteristic of grinding wheels and cutting tools in general. Attritious wear or progressive wear which is typically undesirable leads to the grains dulling by developing flat spots and rounded edges on the wheel which can deteriorate the wheel’s ability to remove material. Flat spots also can lead to excessive heat generation with the added surface contact which in turn enables bond fracture, or the brittle fracture of the adhesive bonds between the grains. The removal of these worn grains from the adhesive bonds restores the wheel’s cutting ability once more. Grinding wheels can also be characterized by the grains’ increased capacity to fracture according to a level of higher value of friability. Different bonding materials are used depending on the intended use of the grinding wheel. The bonding material is classified by its individual strength called its wheel grade.
Grinding forces.
The longevity and cutting ability of a grinding wheel can be affected by the grinding forces generated while in use. Experimental investigation has revealed a direct relationship between cutting speed, wheel geometry, chip geometry, and the grinding forces namely the resultant normal force component ("Fn )," the tangential force component ("Ft )," and their ratio when in contact with a workpiece.
Stage I: As a workpiece enters the grinding zone the initial contact forces are unstable and rise abruptly short period of time and a small wear spot is formed. The overall performance of a wheel during this moment of unstable rising forces can be minimized with proper dressing conditions prior to use and can help effect the high peak and steady state forces which should normally be contained within a short period of time.
Stage II: During the steady state wear stage reaction forces are constant and the flow of heat generation in both the work piece and wheel remain in equilibrium. The measurable data in this stage presents itself as a linear rate of wear as a function of the working duration of the dresser application or tool life ("Td"). The tool life corresponds to the grinding wheels ability to maintain the initial shape give to it during the dressing prior to use. As the workpiece stays full contact with the grinding zone in the steady state of constant forces the flow of heat generation in the work piece and the wheel maintains equilibrium. This phase usually does not produce temperatures that would coincide with bond fracture however the material properties of the bond strength can determine the maximum applied force the wheel grit can sustain prior to fracture.
Stage III: Wear rates on the workpiece become detrimental while the rate of change in reaction forces decreases. The end of tool-life represent the initial dressing condition are no longer effective. The rate of change of forces generated in this stage are minimal and wear on the workpiece as an exponential tendency.
Effects of cutting temperature.
The lifespan of the grinding wheel and final surface properties of the workpiece are directly affected by the operating cutting temperature. Heat generated during grinding penetrates the grinding wheel and the workpiece which can cause dimensional errors due to thermal expansion
Several adverse effects of a high cutting temperature are as follows:
The addition of grinding fluids can effectively control cutting temperatures to reduce heat induced surface effects on the wheel and workpiece.
High heat flux density may result in the grinding wheel melting and consequently, increased wear. The heat flux (Φ) penetrating the grinding wheel and workpiece depends mainly on the cutting speed (vs) and cutting force (Fc). The temperature of the grinding wheel is related to the density of heat flux (φ = dΦ/dA) generated (which also is directly proportional to the feed rate). An approximate value of the heat flux can be calculated as follows: Φ = Fc • vs
Grinding wheel types.
Grinding wheels can be made with a variety of materials depending on the desired abrasive quality required during use. Abrasive material, natural of synthetic, used in grinding include some common types of grinding wheel geometry.
Abrasive grains.
The process of grinding requires an abrasive component with material properties harder than the workpiece. Most common grinders employ a rotating surface being brought in contact with a work surface. The wheel component of grinder itself is generally composed of abrasive grains held together by a bond structure which contain some amount of porosity.
Wheel speed.
The grinding wheel typically operates at high rotational speeds. The wheel speed depends on several factors, some of which included the grindability of the wheel, the shape of the part, and the material of the workpiece. These properties will affect important parameters such as the surface finish, surface integrity, and wheel wear. Likewise, the grinding wheel speed will depend on which abrasive process is needed and which finishing process is desired.
Dressing.
A worn grinding wheel can be dressed to restore its grinding properties. Dressing a grinding wheel causes new grains to be produced on a glazed or loaded grinding wheel. A glazed grinding wheel is the result of high attritious wear causing the grains to become dull. A loaded grinding wheel is a result of chips clogging the grains on the grinding wheel due to the grinding of soft materials, improper grinding wheel selection processing parameters. In addition to sharpening a grinding wheel dressing can also be used to true a grinding wheel that is out of round or to shape the profile of a grinding wheel to produce specific features on the workpiece.


IBM 1132

The IBM 1132 line printer was the normal printer for the IBM 1130 computer system. It printed 120 character lines at 80 lines per minute. The character set consisted of numbers, upper-case letters and some special characters.
The 1965-introduced 1132 was built around a stripped down IBM 407 printing mechanism. The 407 was IBM's top-of-the-line accounting machine from the 1950s. The 1130 had 120 power transistors, each wired to the print magnet for one printer column. The magnet released a lever that engaged a cam with a spinning clutch shaft. The engaged cam then made one revolution, pushing its print wheel toward the ribbon and paper, thereby printing one character.
As the set of 120 print wheels spun, the 1130 received an interrupt as each of the possible 48 characters was about to move into position. The printing driver software had to quickly output a 120 bit vector designating which transistors were to fire so as to drive the print wheel against the ribbon and paper. This put a big performance burden on the CPU, but resulted in an inexpensive (for the time) printer.
Sometimes a printer output line transistor would fail, resulting in a blank print position. If you knew your way around inside the 1130, it was possible to swap circuit cards so as to move the bad print position to near the right end of the printed line. This kept the 1130 usable until the repair person showed up.
The 1132 came in two models with the following characteristics:


WEA Manufacturing

WEA Manufacturing was the record, tape, and compact disc manufacturing arm of WEA International Inc. from 1978 to 2003, when it was sold and merged into Cinram International, a previous competitor. The last owner when the plant closed was Technicolor.
History.
WEA Manufacturing Inc. was created in 1978–1979 when Warner Communications Inc. purchased two of its longtime suppliers: the record pressing plants Specialty Records Corporation (Olyphant, Pennsylvania) and Allied Record Company (Los Angeles). The company was headquartered in Olyphant, where the original plant was replaced in late 1981 by a new facility which retained the name Specialty Records Corporation. The Specialty Records Corporation name was dropped in 1996 in favor of WEA Manufacturing.
The company invested in CD manufacturing in 1986, matching a $247,000 contribution by economic development corporation Ben Franklin Technology Partners to develop and implement new processes of manufacturing audio CDs and CD-ROMs. BFTP assembled a team of experts in physics, electrical engineering, and thin film technology from the University of Scranton and Lehigh University to carry out the research and development. The Olyphant plant and another plant in Alsdorf, Germany, were expanded to support CD pressing that year, with the Olyphant facility's production commencing first in September 1986.
WEA Manufacturing grew to become one of the largest manufacturers of recorded media in the world.
The company began manufacturing Laserdiscs in July 1991.
The company's DVD division, Warner Advanced Media Operations (WAMO), helped design the high-density format used in DVDs, and manufactured some of the first DVDs in the late 1990s.
The company was sold to Cinram International in October 2003 and no longer exists under the name WEA Manufacturing, but the Olyphant plant continued to operate under its new ownership. In 2005, the company was Lackawanna County's largest employer, with over 2,300 people working at the Olyphant plant.
Cinram closed the former Allied plant in 2006, while Technicolor (which purchased Cinram's assets in 2015) closed the Olyphant plant in 2018.
Patents.
WEA Manufacturing held U.S. patents related to compact disc manufacture:
Litigation.
In 1990, WEA Manufacturing was sued by a Canadian firm, Optical Recording Co. (ORC), for alleged infringement of two 1971 patents related to glass mastering equipment which was used by Time Warner and WEA Manufacturing in the manufacture of approximately 450 million CDs. ORC contended that unlike five other major CD manufacturers in the U.S., Time Warner had refused to license the technology from ORC. In 1992, a jury assessed damages of 6 cents per disc, plus $4–5 million in interest.


Leather punch

A leather punch is a hole punch specifically for making holes in leather. The working tip of the punch is a hollow steel cylinder with a sharp circular knife-like edge. The leather piece is placed on a hard surface, which may be a part of the tool set, and the punch is forced through it, cutting out a small circular piece which is discarded. The punch may be a simple metal tool struck with a hammer; or several such punches may be mounted on a rotary turret on a pliers-like tool with an anvil, with the desired size selected by rotating the turret. Hole diameters typically range from about 1mm to 6mm. They are typically used for making holes for buckles, eyelets, and rivets in shoes, belts, bridles, etc.


Contract manufacturer

A contract manufacturer (CM) is a manufacturer that contracts with a firm for components or products (in which case it is a turnkey supplier). It is a form of outsourcing. A contract manufacturer performing packaging operations is called copacker or a "contract packager". Brand name companies focus on product innovation, design and sales, while the manufacturing takes place in independent factories (the turnkey suppliers).
Most turnkey suppliers specialize in simply manufacturing physical products, but some are also able to handle a significant part of the design and customization process if needed. Some turnkey suppliers specialize in one base component (ex. memory chips) or a base process (e.g. plastic molding).
Business model.
In a contract manufacturing business model, the hiring firm approaches the contract manufacturer with a design or formula. The contract manufacturer will quote the parts based on processes, labor, tooling, and material costs. Typically a hiring firm will request quotes from multiple CMs. After the bidding process is complete, the hiring firm will select a source, and then, for the agreed-upon price, the CM acts as the hiring firm's factory, producing and shipping units of the design on behalf of the hiring firm.
Job production is, in essence, manufacturing on a contract basis, and thus it forms a subset of the larger field of contract manufacturing. But the latter field also includes, in addition to jobbing, a higher level of outsourcing in which a product-line-owning company entrusts its entire production to a contractor, rather than just outsourcing parts of it.
Industries that use the practice.
Many industries use this process, especially the aerospace, defense, computer, semiconductor, energy, medical, food manufacturing, personal care, packaging, and automotive fields. Some types of contract manufacturing include CNC machining, complex assembly, aluminum die casting, grinding, broaching, gears, and forging. The pharmaceutical industry uses this process with CMs called contract manufacturing organizations, constituting a $14 billion business segment around 2022. In the semiconductor industry, this practice is called the foundry model. Contract manufacturing is specially prevalent in the electronics industry.
Purpose, benefits, and risks.
There are many benefits as well as risks to contract manufacturing. Companies are finding many reasons why they should outsource their production to other companies. However, production outside of the company has many risks attached. Companies must first identify their core competencies before deciding about contract manufacturers. A company's competencies are what make them competitive in the marketplace. If a company allows another company to take control of them, it loses that advantage.
When deciding about contract manufacture, the company should weigh the benefits and associated risks. For small companies, contract manufacturing may not be a good business strategy. For large companies that are trying to extend into new markets, contract manufacturing may be a good choice.
Protectionism.
In an international context, establishing a foreign subsidiary as a contract manufacturer can have favorable tax benefits for the parent company, allowing them to reduce overall tax liabilities and increase profits, depending upon the activities of the contract manufacturer. This is a form of true protectionism.
The iPad and iPhone, which are products of Apple Inc., are manufactured in China by Foxconn. Some devices may also be manufactured by Pegatron. Apple may move some fraction of iPhone assembly into the United States in the near future.


Rapid casting

Rapid casting is an integration of investment casting with rapid prototyping/3D printing. In this technique disposable patterns that are used for forming molds are created with 3D printing techniques like fused deposition modeling, stereolithography or any other 3D printing technique.


Overpackaging

Overpackaging is the use of excess packaging. The Institute of Packaging Professionals defines overpackaging as “a condition where the methods and materials used to package an item exceed the requirements for adequate containment, protection, transport, and sale”
Overpackaging is an opportunity for source reduction, reducing waste before it is generated by proper package design and practice. Elimination of excess packaging is at the lead of the Reduce, reuse, recycle hierarchy. Use of minimized packaging is key to having sustainable packaging. Examples of overpackaging can be found in many areas; from e-commerce to retail food packaging.
Some examples of overpackaging are obvious while others are more of a judgement call. For example, luxury packaging frequently uses more packaging than the minimum requirements. Brand managers believe that premium packaging is needed to communicate the extra value the contents. Also. gift wrapping can involve excess packaging but traditions and personal choices allow people to continue to use it. Decorative boxes are an "art form" which clearly exceed minimum functional requirements.
Excess packaging by design.
An example of a wasteful package design is a breakfast cereal box (some other products also). This is typically a folding carton enclosing a plastic bag of cereal. Cartons are frequently tall and wide but very thin. This has a poor material to volume ratio and is very inefficient; it is very wasteful. Package designers are aware of this opportunity to save packaging costs, materials, and waste but marketing and merchandising people want the “billboard” style package for advertising and graphics. An optimized folding carton would use much less paperboard for the same volume of cereal, but with reduced room for graphics. Use of only a resealable plastic bag would use even less material per unit of cereal; Of course, even that option results with an empty plastic bag to discard.
Underfilled packages.
Underfilled or "slackfill" packaging is that which is intentionally too large for the contents, resulting in non-functional headspace. This not only risks charges of "deceptive packaging" but it involves excessive packaging: unnecessary packaging waste.
E-commerce.
Sometimes a package is properly designed to protect its product for controlled distribution to a retail store; packaging is minimal. With online shopping or E-commerce, however, items packed for retail sale need to be shipped individually by the e-tailer or by a fulfillment house. The individual package is shipped and handled by package delivery or small parcel carriers. Retail packages are frequently packed into a larger corrugated box for shipment. Often these secondary boxes are much larger than needed, thus use void-fill to immobilize the contents. This can have the appearance of gross overpackaging.
If the product manufacturer designed all packaging to meet the requirements of individual shipment, then the portion delivered to a retail store would have excessive packaging.
With fragile items such as consumer electronics, engineers try to match the fragility of the product with the expected stresses of distribution handling. Package cushioning is used to help ensure safe delivery of the product. With overpackaging, excessive cushioning and a larger corrugated box are used: wasteful packaging.
Sometimes two levels of packaging are needed for separate distribution: one for palletize shipment to retail stores and the other designed for individual delivery to households, which results in production inefficiency. New package designs are sometimes called for.
Food overwraps.
Fresh produce is usually presented for sale without packages, allowing shoppers to touch the items and choose which ones to buy. Some foods are over wrapped with shrink film, individually bagged, or further protected to increase the appeal to some customers. This extra packaging is sometimes considered excessive and unnecessary.


Ironing (metalworking)

Ironing is a sheet metal forming process that uniformly thins the workpiece in a specific area.
This is a very useful process when employed in combination with deep drawing to produce a uniform wall thickness part with greater height-to-diameter ratio. One example of ironing can be found in the manufacture of aluminum beverage cans, which are actually pressed from flat sheets of thicker material.


Package on a package

Package on a package (PoP) is an integrated circuit packaging method to vertically combine discrete logic and memory ball grid array (BGA) packages. Two or more packages are installed atop each other, i.e. stacked, with a standard interface to route signals between them. This allows higher component density in devices, such as mobile phones, personal digital assistants (PDA), and digital cameras, at the cost of slightly higher height requirements. Stacks with more than 2 packages are uncommon, due to heat dissipation considerations.
Configuration.
Two widely used configurations exist for PoP:
During PCB assembly, the bottom package of a PoP stack is placed directly on the PCB, and the other package(s) of the stack are stacked on top.
The packages of a PoP stack become attached to each other (and to the PCB) during reflow soldering.
Benefits.
The package on a package technique tries to combine the benefits of traditional packaging with the benefits of die-stacking techniques, while avoiding their drawbacks.
Traditional packaging places each die in its own package, a package designed for normal PCB assembly techniques that place each package directly on the PCB side-by-side.
The 3D die-stacking system in package (SiP) techniques stacks multiple die in a single package, which has several advantages and also some disadvantages compared to traditional PCB assembly.
In embedded PoP techniques, chips are embedded in a substrate on the bottom of the package. This PoP technology enables smaller packages with shorter electrical connections and is supported by companies such as Advanced Semiconductor Engineering (ASE).
Advantages over traditional isolated-chip packaging.
The most obvious benefit is motherboard space savings. PoP uses much less PCB area, almost as little as stacked-die packages.
Electrically, PoP offers benefits by minimizing track length between different interoperating parts, such as a controller and memory. This yields better electrical performance of devices, since shorter routing of interconnections between circuits yields faster signal propagation and reduced noise and cross-talk.
Advantages over chip stacking.
There are several key differences between stacked-die and stacked-package products.
The main financial benefit of package on a package is that the memory device is decoupled from the logic device. Therefore this gives PoP all the same advantages that traditional packaging has over stacked-die products:
Other names.
Package on a package is also known by other names:
History.
In 2001, a Toshiba research team including T. Imoto, M. Matsui and C. Takubo developed a "System Block Module" wafer bonding process for manufacturing 3D integrated circuit (3D IC) packages. The earliest known commercial use of a 3D package-on-package chip was in Sony's PlayStation Portable (PSP) handheld game console, released in 2004. The PSP hardware includes eDRAM (embedded DRAM) memory manufactured by Toshiba in a 3D package chip with two dies stacked vertically. Toshiba called it "semi-embedded DRAM" at the time, before later calling it a stacked "chip-on-chip" (CoC) solution.
In April 2007, Toshiba commercialized an eight-layer 3D chip package, the 16GB THGAM embedded NAND flash memory chip, which was manufactured with eight stacked 2GB NAND flash chips. The same month, ("Package-on-package secure module having anti-tamper mesh in the substrate of the upper package") was filed by Steven M. Pope and Ruben C. Zeta of Maxim Integrated. In September 2007, Hynix Semiconductor introduced 24-layer 3D packaging technology, with a 16GB flash memory chip that was manufactured with 24 stacked NAND flash chips using a wafer bonding process.


Design rule checking

In electronic design automation, a design rule is a geometric constraint imposed on circuit board, semiconductor device, and integrated circuit (IC) designers to ensure their designs function properly, reliably, and can be produced with acceptable yield. Design rules for production are developed by process engineers based on the capability of their processes to realize design intent. Electronic design automation is used extensively to ensure that designers do not violate design rules; a process called design rule checking (DRC). DRC is a major step during physical verification signoff on the design, which also involves LVS (layout versus schematic) checks, XOR checks, ERC (electrical rule check), and antenna checks. The importance of design rules and DRC is greatest for ICs, which have micro- or nano-scale geometries; for advanced processes, some fabs also insist upon the use of more restricted rules to improve yield.
Design rules.
Design rules are a series of parameters provided by semiconductor manufacturers that enable the designer to verify the correctness of a mask set. Design rules are specific to a particular semiconductor manufacturing process. A design rule set specifies certain geometric and connectivity restrictions to ensure sufficient margins to account for variability in semiconductor manufacturing processes, so as to ensure that most of the parts work correctly.
The most basic design rules are shown in the diagram on the right. The first are single layer rules. A "width" rule specifies the minimum width of any shape in the design. A "spacing" rule specifies the minimum distance between two adjacent objects. These rules will exist for each layer of semiconductor manufacturing process, with the lowest layers having the smallest rules (typically 100 nm as of 2007) and the highest metal layers having larger rules (perhaps 400 nm as of 2007).
A two layer rule specifies a relationship that must exist between two layers. For example, an "enclosure" rule might specify that an object of one type, such as a contact or via, must be covered, with some additional margin, by a metal layer. A typical value as of 2007 might be about 10 nm.
There are many other rule types not illustrated here. A "minimum area" rule is just what the name implies. Antenna rules are complex rules that check ratios of areas of every layer of a net for configurations that can result in problems when intermediate layers are etched. Many other such rules exist and are explained in detail in the documentation provided by the semiconductor manufacturer.
Academic design rules are often specified in terms of a scalable parameter, λ, so that all geometric tolerances in a design may be defined as integer multiples of λ. This simplifies the migration of existing chip layouts to newer processes. Industrial rules are more highly optimized, and only approximate uniform scaling. Design rule sets have become increasingly more complex with each subsequent generation of semiconductor process.
Software.
The main objective of design rule checking (DRC) is to achieve a high overall yield and reliability for the design. If design rules are violated the design may not be functional. To meet this goal of improving die yields, DRC has evolved from simple measurement and Boolean checks, to more involved rules that modify existing features, insert new features, and check the entire design for process limitations such as layer density. A completed layout consists not only of the geometric representation of the design, but also data that provides support for the manufacture of the design. While design rule checks do not validate that the design will operate correctly, they are constructed to verify that the structure meets the process constraints for a given design type and process technology.
DRC software usually takes as input a layout in the GDSII standard format and a list of rules specific to the semiconductor process chosen for fabrication. From these it produces a report of design rule violations that the designer may or may not choose to correct. Carefully "stretching" or waiving certain design rules is often used to increase performance and component density at the expense of yield.
DRC products define rules in a language to describe the operations needed to be performed in DRC. For example, Mentor Graphics uses Standard Verification Rule Format (SVRF) language in their DRC rules files and Magma Design Automation is using Tcl-based language. A set of rules for a particular process is referred to as a run-set, rule deck, or just a deck.
DRC is a very computationally intense task. Usually DRC checks will be run on each sub-section of the ASIC to minimize the number of errors that are detected at the top level. If run on a single CPU, customers may have to wait up to a week to get the result of a Design Rule check for modern designs. Most design companies require DRC to run in less than a day to achieve reasonable cycle times since the DRC will likely be run several times prior to design completion. With today's processing power, full-chip DRC's may run in much shorter times as quick as one hour depending on the chip complexity and size.
Some example of DRC's in IC design include:
Commercial.
Major products in the "DRC" area of "EDA" include:


Kanban

Kanban (Japanese: カンバン and Chinese: 看板, meaning signboard or billboard) is a scheduling system for lean manufacturing (also called just-in-time manufacturing, abbreviated JIT). Taiichi Ohno, an industrial engineer at Toyota, developed kanban to improve manufacturing efficiency. The system takes its name from the cards that track production within a factory. Kanban is also known as the "Toyota nameplate system" in the automotive industry.
In kanban, problem areas are highlighted by measuring lead time and cycle time of the full process and process steps. One of the main benefits of kanban is to establish an upper limit to work in process (commonly referred as "WIP") inventory to avoid overcapacity. Other systems with similar effect exist, for example CONWIP. A systematic study of various configurations of kanban systems, such as "generalized kanban" or "production authorization card" (PAC) and "extended kanban", of which CONWIP is an important special case, can be found in Tayur (1993), and more recently Liberopoulos and Dallery (2000), among other papers.
A goal of the kanban system is to limit the buildup of excess inventory at any point in production. Limits on the number of items waiting at supply points are established and then reduced as inefficiencies are identified and removed. Whenever a limit is exceeded, this points to an inefficiency that should be addressed.
Origins.
The system originates from the simplest visual stock replenishment signaling system, an empty box. This was first developed in the UK factories producing Spitfires during the Second World War, and was known as the "two bin system." In the late 1940s, Toyota started studying supermarkets with the idea of applying shelf-stocking techniques to the factory floor. In a supermarket, customers generally retrieve what they need at the required time—no more, no less. Furthermore, the supermarket stocks only what it expects to sell in a given time, and customers take only what they need, because future supply is assured. This observation led Toyota to view a process as being a customer of one or more preceding processes and to view the preceding processes as a kind of store.
Kanban aligns inventory levels with actual consumption. A signal tells a supplier to produce and deliver a new shipment when a material is consumed. This signal is tracked through the replenishment cycle, bringing visibility to the supplier, consumer, and buyer.
Kanban uses the rate of demand to control the rate of production, passing demand from the end customer up through the chain of customer-store processes. In 1953, Toyota applied this logic in their main plant machine shop.
Operation.
A key indicator of the success of production scheduling based on demand, "pushing," is the ability of the demand-forecast to create such a "push". Kanban, by contrast, is part of an approach where the "pull" comes from demand and products are made to order. Re-supply or production is determined according to customer orders.
In contexts where supply time is lengthy and demand is difficult to forecast, often the best one can do is to respond quickly to observed demand. This situation is exactly what a kanban system accomplishes, in that it is used as a demand signal that immediately travels through the supply chain. This ensures that intermediate stock held in the supply chain are better managed, and are usually smaller. Where the supply response is not quick enough to meet actual demand fluctuations, thereby causing potential lost sales, a stock building may be deemed more appropriate and is achieved by placing more kanban in the system.
Taiichi Ohno stated that to be effective, kanban must follow strict rules of use. Toyota, for example, has six simple rules, and close monitoring of these rules is a never-ending task, thereby ensuring that the kanban does what is required.
Toyota's six rules.
Toyota has formulated six rules for the application of kanban:
Kanban (cards).
Kanban cards are a key component of kanban and they signal the need to move materials within a production facility or to move materials from an outside supplier into the production facility. The kanban card is, in effect, a message that signals a depletion of product, parts, or inventory. When received, the kanban triggers replenishment of that product, part, or inventory. Consumption, therefore, drives demand for more production, and the kanban card signals demand for more product—so kanban cards help create a demand-driven system.
It is widely held by proponents of lean production and manufacturing that demand-driven systems lead to faster turnarounds in production and lower inventory levels, helping companies implementing such systems be more competitive.
In the last few years, systems sending kanban signals electronically have become more widespread. While this trend is leading to a reduction in the use of kanban cards in aggregate, it is still common in modern lean production facilities to find the use of kanban cards. In various software systems, kanban is used for signalling demand to suppliers through email notifications. When stock of a particular component is depleted by the quantity assigned on kanban card, a "kanban trigger" is created (which may be manual or automatic), a purchase order is released with predefined quantity for the supplier defined on the card, and the supplier is expected to dispatch material within a specified lead-time.
Kanban cards, in keeping with the principles of kanban, simply convey the need for more materials. A red card lying in an empty parts cart conveys that more parts are needed.
Three-bin system.
An example of a simple kanban system implementation is a "three-bin system" for the supplied parts, where there is no in-house manufacturing. One bin is on the factory floor (the initial demand point), one bin is in the factory store (the inventory control point), and one bin is at the supplier. The bins usually have a removable card containing the product details and other relevant information, the classic kanban card.
When the bin on the factory floor is empty (because the parts in it were used up in a manufacturing process), the empty bin and its kanban card are returned to the factory store (the inventory control point). The factory store replaces the empty bin on the factory floor with the full bin from the factory store, which also contains a kanban card. The factory store sends the empty bin with its kanban card to the supplier. The supplier's full product bin, with its kanban card, is delivered to the factory store; the supplier keeps the empty bin. This is the final step in the process. Thus, the process never runs out of product—and could be described as a closed loop, in that it provides the exact amount required, with only one spare bin so there is never oversupply. This 'spare' bin allows for uncertainties in supply, use, and transport in the inventory system. A good kanban system calculates just enough kanban cards for each product. Most factories that use kanban use the colored board system (heijunka box).
Electronic kanban.
Many manufacturers have implemented electronic kanban (sometimes referred to as e-kanban) systems. These help to eliminate common problems such as manual entry errors and lost cards. E-kanban systems can be integrated into enterprise resource planning (ERP) systems, enabling real-time demand signaling across the supply chain and improved visibility. Data pulled from e-kanban systems can be used to optimize inventory levels by better tracking supplier lead and replenishment times.
E-kanban is a signaling system that uses a mix of technology to trigger the movement of materials within a manufacturing or production facility. Electronic kanban differs from traditional kanban in using technology to replace traditional elements like kanban cards with barcodes and electronic messages like email or electronic data interchange.
A typical electronic kanban system marks inventory with barcodes, which workers scan at various stages of the manufacturing process to signal usage. The scans relay messages to internal/external stores to ensure the restocking of products. Electronic kanban often uses the Internet as a method of routing messages to external suppliers and as a means to allow a real-time view of inventory, via a portal, throughout the supply chain.
Organizations like the Ford Motor Company and Bombardier Aerospace have used electronic kanban systems to improve processes. Systems are now widespread from single solutions or bolt on modules to ERP systems.
Types of kanban systems.
In a kanban system, adjacent upstream and downstream workstations communicate with each other through their cards, where each container has a kanban associated with it. Economic order quantity is important. The two most important types of kanbans are:
The Kanban philosophy and task boards are also used in agile project management to coordinate tasks in project teams. An online demonstration can be seen in an "agile" simulator.
Implementation of kanban can be described in the following manner:
Kanbrain.
A third type involves corporate training. Following the just-in-time principle, computer-based training permits those who need to learn a skill to do so when the need arises, rather than take courses and lose the effectiveness of what they've learned from lack of practice.


Superplasticity

In materials science, superplasticity is a state in which solid crystalline material is deformed well beyond its usual breaking point, usually over about 400% during tensile deformation. Such a state is usually achieved at high homologous temperature. Examples of superplastic materials are some fine-grained metals and ceramics. Other non-crystalline materials (amorphous) such as silica glass ("molten glass") and polymers also deform similarly, but are not called superplastic, because they are not crystalline; rather, their deformation is often described as Newtonian fluid. Superplastically deformed material gets thinner in a very uniform manner, rather than forming a "neck" (a local narrowing) that leads to fracture. Also, the formation of microvoids, which is another cause of early fracture, is inhibited.
Superplasticity must not be confused with superelasticity.
Historical developments of superplasticity.
Some evidence of superplastic-like flow in metals has been found in some artifacts, such as in Wootz steels in ancient India, even though superplasticity was first scientific recognition in the twentieth century in the report on 163% elongation in brass by Bengough in 1912. Later, Jenkins' higher elongation of 300% in Cd–Zn and Pb–Sn alloys in 1928. However, those works did not go further to set a new phenomenon of mechanical properties of materials. Until the work of Pearson was published in 1934, a significant elongation of 1950% was found in Pb–Sn eutectic alloy. It was easy to become the most extensive elongation report in scientific investigation at this time. There was no further interest in superplasticity in the Western World for more than 25 years after Pearson’s effort. Later, Bochvar and Sviderskaya continued superplasticity in the Soviet Union with many publications on Zn–Al alloys. A research institute focused on superplasticity, the Institute of Metals Superplasticity Problems, was established in 1985 in Ufa City, Russia. This institute has remained the only global institute to work exclusively to research in superplasticity. The interest in superplasticity rose in 1982 when the first major international conference on ‘Superplasticity in Structural Materials, edited by Paton and Hamilton, was held in San Diego. From there, numerous investigations have been published with considerable results. Superplasticity is now the background for superplastic deformation forming as an essential aerospace application technique.
Conditions.
In metals and ceramics, requirements for it being superplastic include a fine grain size (less than approximately 10 micrometers) and an operating temperature that is often from above a half absolute melting point. Several studies have found superplasticity in coarse-grain materials. However, the scientific community has agreed the grain size threshold at 10 micrometers is the precondition for activating superplasticity. Generally, grain growth at high-temperature, therefore maintaining the fine grain size structure at homologous temperature, is the main challenge in superplasticity research. The typical microstructure strategy uses a fine dispersion of thermally stable particles, which pin the grain boundaries and maintain the fine grain structure at the high temperatures and existence of multiple phases required for superplastic deformation. The alloy's most typical microstructure for superplasticity is eutectic or eutectoid structure, as found in Sn-Pb, or Zn-Alloy alloys.
Those materials that meet these parameters must still have a strain rate sensitivity (a measurement of the way the stress on a material reacts to changes in strain rate) of >0.3 to be considered superplastic. The ideal strain rate sensitivity is 0.5, typically found in micro duplex alloys.
Mechanism.
The mechanisms of superplasticity in metals are determined as the Grain Boundary Sliding (GBS). However, the grain boundary sliding (GBS) can lead to the stress concentration at the triple junction or the grain boundary of the hard phases. Therefore, the GBS in polycrystal structured materials must be accompanied by other accommodation processes such as diffusion or dislocation. The diffusion models proposed by Ashby and Verall explain a gradual change in grain shapes to maintain the compatibility between the grains during the deformation. The changes in grain shape are operated by diffusion. The grain boundary migrates to form an equiaxed shape with a new orientation compared to the original grains. The dislocation model is explained as the stress concentration by GBS will be relaxed by dislocation motion in the blocking grains. The dislocation piles up, and the climb would allow another dislocation to be emitted. The further detail in dislocation model is still under debate, with several proposed by Crossman and Ashby, Langdon, and Gifkins model.
High strain Rate Superplasticity.
In general, superplasticity often occurs at a slow strain rate, in order of 10−4 s−1, and can be energy-consuming. In addition, prolonged time exposed to high-operation temperature also degraded the mechanical properties of materials. There is a strong demand to increase the strain rate in superplastic deformation to the order of 10−2 s−1, called High strain Rate Superplasticity (HSRS). Increment of strain rate in superplastic deformation is generally achieved by reduction of grain size in the ultrafine range from 100 to less than 500 ums. Further grain refinement to nanocrystalline structure with grain size less than 100 nm is ineffective in raising the deformation rate or improving ductility. The most common grain refinement process for HSRS research uses Severe Plastic Deformation (SPD). SPD can fabricate exceptional grain refinement to the sub-micrometer or even the nanometer range. Among many SPD techniques, the two most widely used techniques are equal-channel angular pressing (ECAP) and high-pressure torsion (HPT). Besides producing the ultrafine grain size, these techniques also provide a high fraction of high-angle boundaries. These high-angle grain boundaries are a specific benefit to increase the strain rates of deformation. Of the importance of grain refinement processing to superplasticity research, ECAP and HPT have been devoted to mainstream positions in superplasticity studies in metals.
Advantages of superplastic forming.
The process offers a range of important benefits, from both the design and production aspects. To begin with there is the ability to form components with double curvature and smooth contours from single sheet in one operation, with exceptional dimensional accuracy and surface finish, and none of the "spring back" associated with cold forming techniques. Because only single surface tools are employed, lead times are short and prototyping is both rapid and easy, because a range of sheet alloy thicknesses can be tested on the same tool.
Forming techniques.
There are three forming techniques currently in use to exploit these advantages. The method chosen depends upon design and performance criteria such as size, shape, and alloy characteristics.
Cavity forming.
A graphite-coated blank is put into a heated hydraulic press. Air pressure is then used to force the sheet into close contact with the mould. At the beginning, the blank is brought into contact with the die cavity, hindering the forming process by the blank/die interface friction. Thus, the contact areas divide the single bulge into a number of bulges, which are undergoing a free bulging process. The procedure allows the production of parts with relatively exact outer contours. This forming process is suitable for the manufacturing of parts with smooth, convex surfaces.
Bubble forming.
A graphite coated blank is clamped over a 'tray' containing a heated male mould. Air pressure forces the metal into close contact with the mould. The difference between this and the female forming process is that the mould is, as stated, male and the metal is forced over the protruding form. For the female forming the mould is female and the metal is forced into the cavity.
The tooling consists of two pressure Chambers and a counter punch, which is linearly displaceable. Similar to the cavity forming technology, at the process beginning, the firmly clamped blank is bulged by gas pressure.
The second phase of the process involves the material being formed over the punch surface by applying a pressure against the previous forming direction. Due to a better material use, which is caused by process conditions, blanks with a smaller initial thickness compared to cavity forming can be used. Thus, the bubble forming technology is particularly suitable for parts with high forming depths.
Diaphragm forming.
A graphite coated blank is placed into a heated press. Air pressure is used to force the metal into a bubble shape before the male mold is pushed into the underside of the bubble to make an initial impression. Air pressure is then used from the other direction to final form the metal around the male mould. This process has long cycle times because the superplastic strain rates are low. Product also suffers from poor creep performance due to the small grain sizes and there can be cavitation porosity in some alloys. Surface texture is generally good however. With dedicated tooling, dies and machines are costly. The main advantage of the process is that it can be used to produce large complex components in one operation. This can be useful for keeping the mass down and avoiding the need for assembly work, a particular advantage for aerospace products. For example, the diaphragm-forming method (DFM) can be used to reduce the tensile flow stress generated in a specific alloy matrix composite during deformation.
Aluminium and aluminium based alloys.
Superplastically formed (SPF) aluminium alloys have the ability to be stretched to several times their original size without failure when heated to between 470 and 520 °C. These dilute alloys containing zirconium, later known by the trade name SUPRAL, were heavily cold worked to sheet and dynamically crystallized to a fine stable grain size, typically 4–5 μm, during the initial stages of hot deformation. Also superplastic forming is a net-shape processing technology that dramatically decreases fabrication and assembly costs by reducing the number of parts and the assembly requirements. Using SPF technology, it was anticipated that a 50% manufacturing cost reduction can be achieved for many aircraft assemblies, such as the nose cone and nose barrel assemblies. Other spin-offs include weight reduction, elimination of thousands of fasteners, elimination of complex featuring and a significant reduction in the number of parts. The breakthrough for superplastic Al-Cu alloys was made by Stowell, Watts and Grimes in 1969 when the first of several dilute aluminium alloys (Al-6% Cu-0.5%Zr) was rendered superplastic with the introduction of relatively high levels of zirconium in solution using specialized casting techniques and subsequent electrical treatment to create extremely fine precipitates.
Commercial alloys.
Some commercial alloys have been thermo-mechanically processed to develop superplasticity. The main effort has been on the Al 7000 series alloys, Al-Li alloys, Al-based metal-matrix composites, and mechanically alloyed materials.
Aluminium alloy composites.
Aluminium alloy and its composites have wide applications in automotive industries. At room temperature, composites usually have higher strength compared to its component alloy. At high temperature, aluminium alloy reinforced by particles or whiskers such as , and SiC can have tensile elongation more than 700%. The composites are often fabricated by powder metallurgy to ensure fine grain sizes and the good dispersion of reinforcements. The grain size that allows the optimal superplastic deformation to happen is usually 0.5~1 μm, less than the requirement of conventional superplasticity. Just like other superplastic materials, the strain rate sensitivity m is larger than 0.3, indicating good resistance against local necking phenomenon. A few aluminium alloy composites such as 6061 series and 2024 series have shown high strain rate superplasticity, which happens in a much higher strain rate regime than other superplastic materials. This property makes aluminium alloy composites potentially suitable for superplastic forming because the whole process can be done in a short time, saving time and energy.
Deformation mechanism for aluminium alloy composites.
The most common deformation mechanism in aluminium alloy composites is grain boundary sliding (GBS), which is often accompanied by atom/dislocation diffusion to accommodate deformation. The GBS mechanism model predicts a strain rate sensitivity of 0.3, which agrees with most of the superplastic aluminium alloy composites. Grain boundary sliding requires the rotation or migration of very fine grains at relatively high temperature. Therefore, the refinement of grain size and the prevention of grain growth at high temperature is of importance.
The very high temperature (close to melting point) is also said to be related to another mechanism, interfacial sliding, because at high temperatures, partial liquids appear in the matrix. The viscosity of the liquid plays the main role to accommodate the sliding of adjacent grain boundaries. The cavitation and stress concentration caused by the addition of second phase reinforcements are inhibited by the flow of liquid phase. However, too much liquid leads to voids thus deteriorating the stability of the materials. So temperature close to but not exceeding too much the initial melting point is often the optimal temperature. The partial melting could lead to the formation of filaments at the fracture surface, which can be observed under scanning electron microscope. The morphology and chemistry of reinforcements also have influence on the superplasticity of some composites. But no single criterion has yet been proposed to predict their influences.
Methods to improve superplasticity.
A few ways have been suggested to optimize the superplastic deformation of aluminium alloy composites, which are also indicative for other materials:
Titanium and titanium based alloys.
In the aerospace industry, Titanium alloys such as Ti–6Al–4V find extensive use in aerospace applications, not only because of their specific high temperature strength, but also because a large number of these alloys exhibit superplastic behavior. Superplastic sheet thermoforming has been identified as a standard processing route for the production of complex shapes, especially and are amenable to superplastic forming (SPF). However, in these alloys the additions of vanadium make them considerably expensive and so, there is a need for developing superplastic titanium alloys with cheaper alloying additions. The Ti-Al-Mn alloy could be such a candidate material. This alloy shows significant post-uniform deformation at ambient and near-ambient temperatures.
Ti-Al-Mn (OT4-1) alloy.
Ti-Al-Mn (OT4-1) alloy is currently being used for aero engine components as well as other aerospace applications by forming through a conventional route that is typically cost, labour and equipment intensive. The Ti-Al-Mn alloy is a candidate material for aerospace applications. However, there is virtually little or no information available on its superplastic forming behaviour. In this study, the high temperature superplastic bulge forming of the alloy was studied and the superplastic forming capabilities are demonstrated.
The bulging process.
The gas pressure bulging of metal sheets has become an important forming method. As the bulging process progresses, significant thinning in the sheet material becomes obvious. Many studies were made to obtain the dome height with respect to the forming time useful to the process designer for the selection of initial blank thickness as well as non-uniform thinning in the dome after forming.
Case study.
The Ti-Al-Mn (OT4-1) alloy was available in the form of a 1 mm thick cold-rolled sheet. The chemical composition of the alloy. A 35-ton hydraulic press was used for the superplastic bulge forming of a hemisphere. A die set-up was fabricated and assembled with the piping system enabling not only the inert gas flushing of the die- assembly prior to forming, but also for the forming of components under reverse pressure, if needed. The schematic diagram of the superplastic forming set-up used for bulge forming with all necessary attachments and the photograph of the top (left) and bottom (right) die for SPF.
A circular sheet (blank) of 118 mm diameter was cut from the alloy sheet and the cut surfaces polished to remove burrs. The blank was placed on the die and the top chamber brought in contact. The furnace was switched on to the set temperature. Once the set temperature was reached the top chamber was brought down further to effect the required blank holder pressure. About 10 minutes were allowed for thermal equilibration. The argon gas cylinder was opened to the set pressure gradually. Simultaneously, the linear variable differential transformer (LVDT), fitted at the bottom of the die, was set for recording the sheet bulge. Once the LVDT reached 45 mm (radius of bottom die), gas pressure was stopped and the furnace switched off. The formed components were taken out when the temperature of the die set had dropped to 600 °C. Easy removal of the component was possible at this stage. Superplastic bulge forming of hemispheres were carried out at temperatures of 1098, 1123, 1148, 1173, 1198 and 1223 K (825, 850, 875, 900, 925 and 950 °C) at forming pressures of 0.2, 0.4, 0.6 and 0.87 MPa. As the bulge forming process progresses, significant thinning in the sheet material becomes obvious. An ultrasonic technique was used to measure the thickness distribution on the profile of the formed component. The components were analyzed in terms of the thickness distribution, thickness strain and thinning factor. Post deformation micro-structural studies were conducted on the formed components in order to analyze the microstructure in terms of grain growth, grain elongation, cavitations, etc.
Results and discussions.
The microstructure of the as-received material with a two-dimensional grain size of 14 μm is shown in Fig. 8. The grain size was determined using the linear intercept method in both the longitudinal and transverse directions of the rolled sheet.
Successful superplastic forming of hemispheres were carried out at temperatures of 1098, 1123, 1148, 1173, 1198 and 1223 K and argon gas forming pressures of 0.2, 0.4, 0.6 and 0.8 MPa. A maximum time limit of 250 minutes was given for the complete forming of the hemispheres. This cut-off time of 250 minutes was given for practical reasons. Fig. 9 shows a photo-graph of the blank (specimen) and a bulge formed component (temperature of 1123 K and a forming gas pressure of 0.6 MPa).
The forming times of successfully formed components at different forming temperatures and pressures. From the travel of the LVDT fitted at the bottom of the die (which measured the bulge height/depth) an estimate of the rate of forming was obtained. It was seen that the rate of forming was rapid initially and decreased gradually for all the temperature and pressure ranges as reported in Table 2. At a particular temperature, the forming time reduced as the forming pressure was increased. Similarly at a given forming pressure, forming time decreased with an increase in temperature.
The thickness of the bulge profile was measured at 7 points including the periphery (base) and pole. These points were selected by taking the line between centre of the hemisphere and base point as reference and offsetting by 15° until the pole point was reached. Hence the points 1, 2, 3, 4 and 5 subtend an angle of 15°, 30°, 45°, 60° and 75° respectively with the base of the hemisphere as shown in Fig. 10. The thickness was measured at each of these points on the bulge profile by using an ultrasonic technique. The thickness values for each of the successfully formed hemispherical components.
Fig. 11 shows the pole thickness of fully formed hemispheres as a function of forming pressure at different temperatures. At a particular temperature the pole thickness reduced as the forming pressure was increased. For all the cases studied the pole thickness lay in the range of about 0.3 to 0.4 mm from the original blank thickness of 1 mm.
The thickness strain formula_1, where formula_2 is the local thickness and formula_3 is the initial thickness, was calculated at different locations for all the successfully formed components. For a particular pressure the thickness strain reduced as the forming temperature was increased. Fig. 12 shows the thickness strain, formula_1 as a function of position along the dome cross section in case of a component formed at 1123 K at a forming pressure of 0.6 MPa.
The post-formed microstructure revealed that there was no significant change in grain size. Fig. 13 shows the microstructure of the bulge formed component at the base and the pole for a component formed at a temperature of 1148 K and forming pressure of 0.6 MPa. These microstructures show no significant change in grain size.
Conclusion.
The high temperature deformation behaviour and superplastic forming capability of a Ti-Al-Mn alloy was studied. Successful forming of 90 mm diameter hemispheres using the superplastic route were carried out at the temperature range of 1098 to 1223 K and forming pressure range of 0.2 to 0.8 MPa. The following conclusions could be drawn:
Iron and steel.
Mostly on non-qualified materials, such as austenitic steel of the Fe-Mn-Al alloy, which has some of the specific material parameters closely related to microstructural mechanisms. These parameters are used as indicators of material superplastic potentiality. The material was submitted to hot tensile testing, within a temperature range from 600 °C to 1000 °C and strain-rates varying from 10−6 to 1 s−1. The strain rate sensitivity parameter (m) and observed maximum elongation until rupture (εr) could be determined and also obtained from the hot tensile test.
Fe with Mn and Al alloys.
The experiments stated a possibility of superplastic behaviour in a Fe-Mn-Al alloy within a temperature range from 700 °C to 900 °C with grain size around 3 μm (ASTM grain size 12) and average strain rate sensitivity of m ∼ 0.54, as well as a maximum elongation at rupture around 600%.
Fe with Al and Ti alloys.
The superplastic behaviour of Fe-28Al, Fe-28Al-2Ti and Fe-28Al-4Ti alloys has been investigated by tensile testing, optical microscopy and transmission electron microscopy. Tensile tests were performed at 700–900 °C under a strain rate range of about 10−5 to 10−2/s. The maximum strain rate sensitivity index m was found to be 0.5 and the largest elongation reached 620%. In Fe3Al and Fe Al alloys with grain sizes of 100 to 600μm exhibit all deformation characteristics of conventional fine grain size superplastic alloys.
However, superplastic behaviour was found in large-grained iron aluminides without the usual requisites for superplasticity of a fine grain size and grain boundary sliding. Metallographic examinations have shown that the average grain size of large-grained iron aluminides decreased during superplastic deformation.
Ceramics.
The properties of ceramics.
The properties of ceramic materials, like all materials, are dictated by the types of atoms present, the types of bonding between the atoms, and the way the atoms are packed together. This is known as the atomic scale structure. Most ceramics are made up of two or more elements. This is called a compound. For example, alumina , is a compound made up of aluminium atoms and oxygen atoms.
The atoms in ceramic materials are held together by a chemical bond. The two most common chemical bonds for ceramic materials are covalent and ionic. For metals, the chemical bond is called the metallic bond. The bonding of atoms together is much stronger in covalent and ionic bonding than in metallic. That is why, generally speaking, metals are ductile and ceramics are brittle. Due to ceramic materials wide range of properties, they are used for a multitude of applications. In general, most ceramics are:
High-strain-rate superplasticity has been observed in aluminium-based and magnesium-based alloys. But for ceramic materials, superplastic deformation has been restricted to low strain rates for most oxides, and nitrides with the presence of cavities leading to premature failure. Here we show that a composite ceramic material consisting of tetragonal zirconium oxide, magnesium aluminates spinal and alpha-alumina phase exhibit superplasticity at strain rates up to 1.0 s−1. The composite also exhibits a large tensile elongation, exceeding 1050% or a strain rate of 0.4 s−1.
Superplastic metals and ceramics have the ability to deform over 100% without fracturing, permitting net-shape forming at high temperatures. These intriguing materials deform primarily by grain boundary sliding, a process accelerated with a fine grain size. However, most ceramics that start with a fine grain size experience rapid grain growth during high temperature deformation, rendering them unsuitable for extended superplastic forming. One can limit grain growth using a minor second phase (Zener pinning) or by making a ceramic with three phases, where grain to grain contact of the same phase is minimized. A research on fine grain three phase alumina-mullite-zirconia, with approximately equal volume fractions of the three phases, demonstrates that superplastic strain rates as high as 10−2/sec at 1500 °C can be reached. These high strain rates put ceramic superplastic forming into the realm of commercial feasibility.
Cavitations.
Superplastic forming will only work if cavitations don't occur during grain boundary sliding, those cavitations leaving either diffusion accommodation or dislocation generation as mechanisms for accommodating grain boundary sliding. The applied stresses during ceramic superplastic forming are moderate, usually 20–50 MPa, usually not high enough to generate dislocations in single crystals, so that should rule out dislocation accommodation. Some unusual and unique features of these three phase superplastic ceramics will be revealed, however, indicating that superplastic ceramics may have a lot more in common with metals than previously thought.
Yttria-stabilized tetragonal zirconia polycrystalline.
Yttrium oxide is used as the stabilizer. This material is predominantly tetragonal in structure. Y-TZP has the highest flexural strength of all the zirconia based materials. The fine grain size of Y-TZP lends itself to be used in cutting tools where a very sharp edge can be achieved and maintained due to its high wear resistance. It is considered to be the first true polycrystalline ceramic shown to be superplastic with a 3-mol %
Y-TZP (3Y-TZP), which is now considered to be the model ceramic system.
The fine grade size leads to a very dense, non-porous ceramic with excellent mechanical strength, corrosion resistance, impact toughness, thermal shock resistance and very low thermal conductivity. Due to its characteristics Y-TZP is used in wear parts, cutting tools and thermal barrier coatings.
Grain size.
Superplastic properties of 3Y-TZP is greatly affected by grain size as displaced in Fig. 3, elongation to failure decreases and flow strength increases while grain size increases. A study was made on the dependence of flow stress on grain size, the result –in summary- shows that the flow stress approximately depends on the grain size squared:
Where:
Alumina .
Alumina is probably one of the most widely used structural ceramics, but superplasticity is difficult to obtain in alumina, as a result of rapid anisotropic grain growth during high-temperature deformation.
Regardless of which, several studies have been performed on superplasticity in doped, fine-grain .Demonstrated that the grain size of containing 500-ppm MgO can be further refined by adding various dopants, such as , and . A grain size of about 0.66 μm was obtained in a 500-ppm -doped . As a result of this fine grain size, the exhibits a rupture elongation of 65% at 1450 °C under an applied stress of 20 MPa.


Chavadipalayam railway station

Chavadipalayam railway station is a station near Erode in Tamil Nadu, India. It is located along the Erode–Tiruchirappalli line between and .
Goods terminal.
A goods terminal has been developed by a private sector company in this station. It has a facility to serve goods traffic of half rake/full rake inward and outward goods from locals through booking.


Footprint (electronics)

A footprint or land pattern is the arrangement of pads (in surface-mount technology) or through-holes (in through-hole technology) used to physically attach and electrically connect a component to a printed circuit board. The land pattern on a circuit board matches the arrangement of leads on a component.
Component manufacturers often produce multiple pin-compatible product variants to allow systems integrators to change the exact component in use without changing the footprint on the circuit board. This can provide large cost savings for integrators, especially with dense BGA components where the footprint pads may be connected to multiple layers of the circuit board.
Many component vendors provide footprints for their components, including Texas Instruments, and CUI. Other sources include third party libraries, such as SnapEDA.


Product optimization

Production optimization is the practice of making changes or adjustments to a product to make it more desirable.
Description.
A product has a number of attributes. For example, a soda bottle can have different packaging variations, flavors, nutritional values. It is possible to optimize a product by making minor adjustments. Typically, the goal is to make the product more desirable and to increase marketing metrics such as Purchase Intent, Believability, Frequency of Purchase, etc.
Methods.
Multivariate optimization is one of the most common methods for product optimization. In this method, multiple product attributes are specified and then tested with consumers.
Due to complex interaction effects between different attributes (for example, consumers frequently associate certain flavors with packaging colors), it is problematic to use mathematical methods, such as Conjoint Analysis, typically used in industrial process optimization.
More recently companies started to adopt Evolutionary Optimization techniques for Product optimization. Evolutionary algorithms (such as IDDEA) are used to optimize products, concepts and messaging.


Hesa Air Base

Hesa Air Base belongs to the Iran's Aircraft Manufacturing Industrial Company HESA and it has been built near of Esfahan.


Decambering

Decambering is the metalworking process of removing camber, or horizontal bend, from strip shaped materials. The material may be finite length sections or continuous coils. Decambering resembles flattening or levelling processes, but deforms the material edge (left or right) instead of the face (up or down) of the strip.
Processes.
Decambering may be accomplished by a choice of several processes:
The material may be "stretchformed" or stretched typically 1-2% elongation past its elastic limit, such that the camber is strained out, and the strip relaxes straight. Typically this is accomplished by routing the strip through two sets of 180 degree or more wrap driven "bridle rolls" with the second rolls rotating faster than the first. Cut strip can be gripped each end then stretched on a static rig with one end being mechanically pulled. The "stretchforming" process is most suited to thin strip.
Wider material can be flat rolled with the rolls tilting such that the "short" edge is lengthened, with thickness slightly reduced, to equal the "long" edge. The material is then straight if properly processed. Several different types of these machines are available, ranging from position controlled to pressure controlled machines. Also, machines are available with automatic self checking features. If the material has residual stress as in toothed bandsaw blades, the rolls must not uniformly apply cross strain, as the inherent strain will distort the strip. In these cases, rolls exert corrective strain in a linear narrow strip inboard of the edge each side. In the case of sawblades with teeth on, the corrective squeezed strip on the toothed edge is located along the tooth gullet, and corrective squeeze on the toothed side must be about 2.5 times the corrective force on the plain edge.
If the strip is narrow and thick enough, side rolls with guide grooves can be used to bend the material laterally to remove the camber. There are many patented designs of these machines, with the best engaging the material on both edges of the strip over the worked portion, preventing the material from twisting or "cheating" the corrective lateral bending.
Note that camber is often caused by slitting, where slitting knives extend the edge being slit. Outer edges left untreated usually have a shorter length than the inner edges being formed by slitting. The outer mults from slitting will therefore usually have camber, while inner mults frequently will not. Decamberers are cost effective when material is not laterally straight enough to suit a given process, and needs upgrading. Cambered material is usually lower in cost than straight material, and decamberers offer savings in these cases. Various types of decambering machines cater to wide or narrow materials.
References.
"Decamberer Maintains Lock Bar Straightness" by J. Neiland Pennington, Senior Editor, Modern Metals magazine pp 26–28, July 1997, Trend Publishing, Inc. Chicago, Il 60611–3110.
US patent US6038904 "Decamberer" 2000-03-21, Barnes, Austen
US patent US5904058 "Decamberer" 1999-05-18 Barnes, Austen
German patent DE19857278 "Camber correction for wide strip in rolling mill using pneumatic cylinder actuators to control pressure applied by rolls" 2000-06-21 Barnes, Austen Bernard


Bolpur Lok Sabha constituency

Bolpur Lok Sabha constituency is in West Bengal, in India. While four assembly segments of No. 41 Bolpur Lok Sabha constituency are in Birbhum district, three are in Purba Bardhaman district. The seat was a free seat till 2004, but was declared reserved for scheduled castes from 2009 general elections.
Vidhan Sabha segments.
As per order of the Delimitation Commission issued in 2006 in respect of the delimitation of constituencies in the West Bengal, parliamentary constituency no. 41 Bolpur, reserved for Scheduled castes (SC), is composed of the following assembly segments:
Prior to delimitation, Bolpur Lok Sabha constituency was composed of the following assembly segments:Ausgram (SC) (assembly constituency no. 267), Mangalkot (assembly constituency no. 281), Nanoor (SC) (assembly constituency no. 283), Bolpur (assembly constituency no. 284), Labpur (assembly constituency no. 285), Dubrajpur (assembly constituency no. 286) and Mayureswar (SC) (assembly constituency no. 290)
Election results.
General election 2019.

General election 2014.

1984 Election.
By-election 1985.
A by-election was held in this constituency in 1985 which was necessitated by the Sudden Death of sitting CPIM-MP Dr. Saradish Roy. In the by-election, Somnath Chatterjee of CPIM defeated his nearest rival Siddhartha Shankar Ray of Congress by 98,999 votes.
General elections 1967-2004.
Most of the contests were multi-cornered. However, only winners and runners-up are mentioned below:


Surfware

Surfware, Inc. is a Camarillo, CA-based company involved in the development of CAD/CAM software.
Company history.
In 1950, Victor Diehl opened a mold shop in Southern California for machine tooling medical products. Throughout the 1950s, Victor Diehl focused on precision mold products for the medical industry. In the 1960s, Victor and Alan Diehl got a numerical control machine (CNC) to expedite tooling of components for aircraft manufacturing. Ten years later, Alan and his brother-in-law Jack Epps, a physicist, built a smart NC machine powered by a mini-computer.
In 1980, Bryan and Larry Diehl, joined the machining firm and wrote a UNIX program for surface modeling and machining. In 1988, Surfware, Inc. was formed by Alan and Larry, and SURFCAM was launched—a PC-based modeling and NC programming software to be offered to the CAD/CAM industry.
Over the next decade, SURFCAM's features advanced along with the capabilities of the PC. Started with NURBS surface technology on a PC, PC-based four-axis machining, CAM system for 32-bit architectures, PC CAM system with automatic rendering of blended surfaces, 2- and 3-axis rest machining.
In 2002, Surfware began work on what would become the TrueMill technology, a completely new toolpath strategy that controls the load on the tool to significantly increase CNC productivity extending also tool life for all materials, including aluminum, steels, titanium, Inconel and other exotics. SURFCAM Velocity Powered by Truemill was launched in 2005, this CAD/CAM software limits the maximum stepover to cut optimally everywhere along the toolpath on any part geometry. A patent (US 7,451,013) has been granted to Surfware.Inc for its “Engagement Milling” technology (TrueMill).
Surfware headquarters in Thousand Oaks, California. It maintains its own suite of milling machines to test the latest developments and innovations in the state-of-the-art TrueMill technology.
In 2013 Surfcam was acquired by
In 2014 Vero Software was acquired by


ZW Drive

Shenzhen Zhaowei, commonly known as ZW Drive, is a Shenzhen-based manufacturer of power transmission systems and gearboxes, including micro planetary gearboxes, precision reduction gear boxes, plastic and metal powder-based injection parts and its assemblies. The company also operates five fully-owned subsidiaries.
Company history.
The company was incorporated in 2001. It is active in micro drive systems, gearboxes, gear motor, encoders, and controls. It reported a net profit of 244.7 million yuan in 2020. Zhaowei is listed on the Shenzhen Stock Exchange, completed its successful initial public offering (IPO) in December 2020.
Precision gear mold design and development.
In terms of gear mold design, after years of technology accumulation, the company has mastered the core key technologies of gear mold cavity design methods and tooth shape correction.


The 2011 Abia State House of Assembly election was held on April 26, 2011, to elect members of the Abia State House of Assembly in Nigeria. All the 24 seats were up for election in the Abia State House of Assembly.
Results.
Osisioma South.
PDP candidate Emeka Alozie won the election.
Umuahia North.
PDP candidate Emeka Ejiogu won the election.
Umuahia Central.
PDP candidate Grace Nkera Uche won the election.
Isiala Ngwa North.
PDP candidate Martins Azubuike won the election.
Isiala Ngwa South.
PDP candidate Darlington Nwokocha won the election.
Isuikwuato.
PDP candidate Chukwudi Ogele won the election.
Umuahia East.
PDP candidate Chidiebere Nwoke won the election.
Umunneochi.
PDP candidate Ikedi Ezekwesiri won the election.
Ukwa West.
PDP candidate Mezie Nwaubani won the election.
Ukwa East.
PDP candidate Allwell Asiforo Okere won the election.
Obingwa East.
PDP candidate Princewill Chilaka won the election.
Obingwa West.
PDP candidate Uche Nwankpa won the election.
Umuahia South.
PDP candidate Chidi Nwosu won the election.
Ikwuano.
PDP candidate Emeka Osoagbaka won the election.
Ugwunagbo.
PDP candidate Humphery Azubuike won the election.
Ohafia North.
PDP candidate Ude Oko Chukwu won the election.
Aba Central.
PDP candidate Kate Maduako won the election.
Osisioma North.
PDP candidate Ikechukwu Nwabeke won the election.
Aba North.
PDP candidate Blessing Nwagba won the election.
Arochukwu.
PDP candidate Agwu U. Agwu won the election.
Aba South.
PDP candidate Nwogu Iheasinmo won the election.
Bende North.
PDP candidate Ndukwe Ojukwu won the election.
Bende South.
PDP candidate Princewill Onyegbu won the election.
Ohafia South.
PDP candidate Mba Ukaha won the election.


Advanced packaging (semiconductors)

Advanced packaging is the aggregation and interconnection of components before traditional integrated circuit packaging. Advanced packaging allows multiple devices (electrical, mechanical, or semiconductor) to be merged and packaged as a single electronic device. Unlike traditional integrated circuit packaging, advanced packaging employs processes and techniques that are performed at semiconductor fabrication facilities. Advanced packaging thus sits between fabrication and traditional packaging -- or, in other terminology, between BEoL and post-fab. Advanced packaging includes multi-chip modules, 3D ICs, 2.5D ICs, heterogeneous integration, fan-out wafer-level packaging, system-in-package, quilt packaging, combining logic (processors) and memory in a single package, die stacking, several chiplets or dies in a package, combinations of these techniques, and others.
Advanced packaging can help achieve performance gains through the integration of several devices in one package and associated efficiency gains (by reducing the distances signals have to travel, in other words reducing signal paths), and allowing for high numbers of connections between devices, without having to resort to smaller transistors which have become increasingly more difficult to manufacture.


The 1999 Abia State House of Assembly election was held on January 9, 1999, to elect members of the Abia State House of Assembly in Nigeria. All the 24 seats were up for election in the Abia State House of Assembly.
Results.
Osisioma South.
APP candidate Donatus Nwankpa won the election.
Umuahia North.
PDP candidate Nkem Chris Ike won the election.
Umuahia Central.
PDP candidate Stanley Ohajuruka won the election.
Isiala Ngwa North.
PDP candidate Christopher Enweremadu won the election.
Isiala Ngwa South.
APP candidate Remigius Nji won the election.
Isuikwuato.
PDP candidate Ernest Osita Igbe won the election.
Umuahia East.
APP candidate Dan Egbogu won the election.
Umunneochi.
PDP candidate Matthew Ibeh won the election.
Ukwa West.
PDP candidate Ngozi Ulunwa won the election.
Ukwa East.
PDP candidate Emeka Stanley won the election.
Obingwa East.
PDP candidate Eric Acho Nwakanma won the election.
Obingwa West.
PDP candidate Chima Ochieze won the election.
Umuahia South.
APP candidate Ndukwe Adindu won the election.
Ikwuano.
PDP candidate Wisdom Ogbonna won the election.
Ugwunagbo.
PDP candidate James Maraizu won the election.
Ohafia North.
PDP candidate Tony Okoro Kalu won the election.
Aba Central.
PDP candidate Nnamdi Egege won the election.
Osisioma North.
PDP candidate Kingsley Mgbeahuru won the election.
Aba North.
APP candidate Blessing Azuru won the election.
Arochukwu.
PDP candidate Sampson Orji won the election.
Aba South.
APP candidate Obioma Ekpem won the election.
Bende North.
PDP candidate Lekwauwa Orji won the election.
Bende South.
PDP candidate Emenike Okoroafor won the election.
Ohafia South.
PDP candidate Bernard Orji won the election.


Diamond grinding cup wheel

A diamond grinding cup wheel is a metal-bonded diamond tool with diamond segments welded or cold-pressed on a steel (or other metal, such as aluminum) wheel body, which usually looks like a cup. Diamond grinding cup wheels are usually mounted on concrete grinders to grind abrasive building materials like concrete, granite and marble.
Use.
There are various styles and specifications of diamond grinding cup wheels to fit various application requirements. The ones with many big diamond segments can undertake heavy workloads, for example, grinding concrete and stone, while those with small or sparse diamond segments are normally used for fast removal of paints, wallpapers, glues, epoxy and other surface coatings.
Just like other metal-bonded diamond tools, the diamond segments on diamond grinding cup wheels can have different bonds, different diamond grits, different diamond quality and different diamond concentrations to fit different uses. For example, if the material to be ground is hard, the bond should be softer, and if the material is relatively soft, the bond should be harder.
Diamond grinding cup wheels are used in different-roughness grindings. For coarse grinding, the bond should be softer and the diamonds' quality should be higher, because in this case the diamonds become blunt more easily. The diamond grit should be bigger, normally from 35 grit to 50 grit. For this is coarse grinding and big grit can improve working efficiency. The diamond concentration can be lower.
For fine grinding (sometimes called "polishing"), the bond should be harder and the diamonds' quality can be lower, as in this case the diamonds can last longer and a hard bond can also help the precision of the process. The diamond grit is normally between 80 grit and 120 grit, depending on the grinding requirements. The diamond concentration should be higher.
After being ground, the material can be further polished with resin-bonded diamond polishing pads of different diamond grits.
Manufacturing methods.
There are two common methods to manufacture diamond grinding cup wheels: hot pressing and cold pressing.
The hot pressing method is to directly sinter the diamond segments in molds under a certain pressure in the dedicated sintering press machine, and then fix or connect the diamond segments onto the grinding wheel’s body via high-frequency welding, laser welding or mechanical mosaic method.
The cold pressing method is to first press the working layer (containing diamonds) and the transitive layer (not containing diamonds) of the diamond segments to their forms directly on the grinding wheel's body, and let the segments connect with the wheel's body via teeth, slots or other manners. Then, put the grinding wheels into sintering furnaces to sinter without press.