Fulfillment house

Fulfillment house and fulfillment center (in British English: fulfilment house and fulfilment centre) are modern terms for a packing warehouse. The terms were coined in the middle of the 1990s, and "fulfillment center" is usually used about an in-house packing warehouse, while "fulfillment house" tends to be used about companies that specialize in warehousing and packing for others.
Origin of term.
The usage of the word "'fulfillment" in relation to goods shipments comes from the terms "order fulfillment" and "product fulfillment", which were introduced by business management researchers who analysed supply chains in the late 1980s. This was soon picked up by PR people working for picking warehouse companies, who felt that "fulfillment centre" or "fulfillment house" sounded more positive and active than the old term "warehouse". The terms are still so new and unknown by people outside that industry that "warehouse" often is added in parenthesis or used as an alternative word in the same text, in order to explain to laymen what "fulfillment centre" or "fulfillment house" actually means.
External or internal.
Some companies, such as Amazon, have their own fulfillment centers, while many smaller e-commerce companies outsource their warehousing, picking, packaging and shipping to external fulfillment companies. These external fulfillment companies are known as third-party logistic providers. Many larger companies with their own fulfillment centers also handle warehousing and shipping for other sellers. Amazon itself is one such example, offering to handle warehousing and order fulfillment to third-party sellers. Another, very early, example was Fingerhut, which in the 1990s expanded its own fulfillment center in order to take on fulfillment services for other companies, including the company that eventually acquired Fingerhut: Federated Department Stores.
Types.
There are multiple types of fulfillment houses. In the past, a fulfillment center was typically associated with filling larger commercial orders to a retailer or distributor. Today, with the growth of ecommerce, there are fulfillment centers that strictly focus on shipping small parcels direct-to-consumers (DTC). Additionally, some ecommerce fulfillment centers focus on a niche, such as small or large products, a specific type of product (for example - apparel), or they only with a certain number of stock keeping units (SKUs).
A subset of ecommerce known as drop shipping, a type of product fulfillment that occurs directly from manufacturers to consumers via 3rd party retail websites, utilizes the manufacturer's or a wholesaler's fulfillment centers to deliver goods to the customer. In drop shipping, the company that generates the sale never handles the physical product, but it does pass on fulfillment requirements to the fulfillment house so that customer demands like two-day shipping can be met.
Fulfillment House Due Diligence Scheme.
The UK government believes that fulfillment houses are in a position to facilitate non-payment of VAT on goods imported into the UK. The government argues that this type of abuse is "enabled by misdeclaration and undervaluation of goods imported from outside the EU, and sometimes the abuse of reliefs that are designed to facilitate trade. This is followed by the onward sale of the goods to customers in the UK taking place without the correct amounts of UK VAT being paid" and believes that registering fulfillment houses and requiring due diligence and record-keeping is "part of the solution".
Provision for this "Fulfillment House Due Diligence Scheme" is included in sections 48 to 59 of the Finance Bill 2017, introduced into the UK Parliament in September 2017.


Impact extrusion

Impact extrusion is a manufacturing process similar to extrusion and drawing by which products are made with a metal slug. The slug is pressed at a high velocity with extreme force into a die or mold by a punch.
Process.
The punch is attached to a mechanical or hydraulic press. These machines reciprocate in a cycle 20 to 60 times per minute. A cold slug is placed below the punch and over the die. The punch makes contact with the slug forcing it around the circumference of the punch and into the die. The metal slug deforms to fit the punch on the inside and the die on the outside. Lubricants are added to aid the machine for an easier punch-out. It only takes one impact for the finished shape to form from the slug. Once the slug has been contoured to the desired shape, a counter-punch ejector removes the work piece from within the die.
Some Characteristics of the Process.
The wall thickness of the work piece is directly correlated with the clearance between the punch and die.
The thinner the wall of the work piece the tighter its tolerances are.
The end product has a better surface finish than the starting piece and the grain of the material is reformed to its new shape. This adds strength to the new form compared to cutting into the grain like in a machining process.
Effects on Work Material Properties.
After going through this process the properties of the material used are altered. Its hardness and yield strength are increased, cross-sectional area is decreased, some residual surface stresses will be present and micro cracks may appear. Physical and chemical properties are only influenced slightly.
Die Style.
Four major types of dies (tools) can be used. They are: forward, backward/reverse, combined, and hydrostatic extrusion. Forward extrusion pushes the slug into the die. Backward/reverse extrusion pushes the slug around the punch. Combined extrusion forces the slug both into the die and around the punch. Hydrostatic extrusion is used on brittle materials (i.e. molybdenum, beryllium, and tungsten) by applying pressure gradually to force the brittle material through the die. This is generally accomplished by the same method as forward extrusion.
Typical Workpiece Materials.
Typical materials for this process are: aluminium, brass, tin, mild steel, stainless steel, magnesium, titanium, and zinc.
Tool Materials.
Typical tool steels used in extruding aluminum:
Tool Geometry.
When using the technique of backward impact extrusion, putting an angle on the punch in the press is used to decrease the amount of pressure applied to the punch. This decreases the chance of creating a dead zone, which is an area of no pressure. On the opposite end of things, forward impact extrusion uses a radius on punch to keep the course in the workpiece material moving.


Planing (shaping)

Planing is a manufacturing process of material removal in which the workpiece reciprocates against a stationary cutting tool producing a plane or sculpted surface. Planing is analogous to shaping. The main difference between these two processes is that in shaping the tool reciprocates across the stationary workpiece. Planing motion is the opposite of shaping. Both planing and shaping are rapidly being replaced by milling.
The mechanism used for this process is known as a planer. The size of the planer is determined by the largest workpiece that can be machined on it. The cutting tools are usually carbide tipped or made of high speed steel and resemble those used in facing and turning.
Process.
In shaping, the tool is brought into position with the workpiece. The tool then repeatedly moves in a straight line while the workpiece is incrementally fed into the line of motion of the tool, this produces a flat, smooth, and sculpted surface. For shaped pieces the tool reciprocates across the stationary workpiece. The tools are usually tilted or lifted after each stroke. This is done hydraulically or manually in order to prevent the tool surface from chipping when the workpiece travels back across.
Workpiece geometry.
Planing can be used to produce flat surfaces, as well as cross-sections with grooves and notches, are produced along the length of workpiece. Shaping is basically the same as planing, except the workpiece is usually smaller, and it is the tool that moves and not the workpiece.
Planing can be used to produce horizontal, vertical, or inclined flat surfaces on workpieces usually too large for shaping. Shaping is used not only for flat surfaces, but also for external or internal surfaces (either horizontal or inclined). Curved and irregular surfaces can also be produced by using special attachments
Setup and equipment.
Flat, angular, and contoured surfaces are made by horizontal shapers. Concerning shaping, the device that holds the piece being worked on has a very heavy movable jaw to withstand cutting forces. The size of the planer needed is determined by the workpiece. Depending on the size of the workpiece many clamps and supporting devices may be used to hold it on the planer.
Typical tools and geometry produced.
The tools for shaping/planing are usually made of high speed steel or carbide tipped. Except for some slight angle difference, cutting tools resemble those used in facing and turning. Some advantages of using single-point cutting tools over multipoint tools is that they are more easily sharpened and fabricated. Internal shapes can be made by using a special extension tool.
Material properties.
Although the most common material to be planed or shaped is wood, there are planers and shaping machines capable of processing anything from metal pieces to plastic objects.
References.
[1] Todd, Robert H and Allen, Dell K. (1994) "Manufacturing Processes Reference Guide". New York, NY: Industrial Press Inc. pg. 124-125.


Gear shaping

Gear shaping is a machining process for creating teeth on a gear using a cutter. Gear shaping is a convenient and versatile method of gear cutting. It involves continuous, same-plane rotational cutting of gear.
Process theory.
The types of cutters used for gear shaping can be grouped into four categories: disk, hub, shank, and helical cutters. The cutters are essentially gears that are used to form the teeth. This method of gear cutting is based on the principle that any two gears will mesh if they are of the same pitch, proper helix angle, and proper tooth depth and thickness.
Process characteristics.
By using a gear-shaped corresponding cutter that is rotated (in relation to a blank gear) produces the gear teeth. The cutters that are rotated are timed with the workpiece. This process produces internal gears, external gears, and integral gear-pinion arrangements.
Process schematic.
The process of gear shaping uses a toothed disk cutter which reciprocates in axial rotations. The workpiece (or blank gear) rotates on a second shaft (spindle). The workpiece is aligned with the cutter and it gradually feeds into the cutter while rotating. If a two-step process is used, all tooth spaces are partially cut before finishing.
Setup and equipment.
The machine used for gear shaping generally consists of a base, column spindle, and an arbor. The gear cutter is mounted on the spindle, and the gear blank is mounted on the arbor. The cutter reciprocates up and down while the workpiece is gradually fed into the cutter. At the end of each cutting rotation, the spindle is retracted slightly to discourage any more cutting into the new cut teeth of the gear.


Namiki Precision Jewel Co

 is a Japanese component manufacturing company based in Tokyo, Japan. The company was founded in 1939 as a manufacturer of synthetic sapphire jewel bearings for electrical measuring instruments. Namiki supplies industrial jewel parts, dc coreless and dc brushless motors, multi-functional vibration components, precision gearheads, medical equipment, watch exterior parts, Analog Record-related Products and other precision components.
Namiki merged with its affiliated company, Adamant Co., Ltd. on January 1, 2018, and changed its name to Adamant Namiki Precision Jewel Co., Ltd.. Adamant Namiki Precision Jewel Co., Ltd., and Akita Adamant Co., Ltd., merged in 2023 and the company was rebranded as Orbray Co., Ltd., on January 1, 2023.
Products.
Jewel Parts.
Namiki supplies industrial jewel parts such as jewel bearings, phonograph diamond styli and cantilevers, watch exterior parts, and sapphire wafers which are made of synthetic sapphire which is produced in-house. They have developed sapphire step wafers, with a step height of 0.22 nanometres, which are expected to become the height standard for scanning probe microscopy (SPM), plus Immobilization plates for observing bio-materials.
DC Motors.
Namiki supplies DC coreless motors, DC brushless motors and geared motors. In 2004, they developed the world's smallest micro geared motor (diameter 1.5mm) for use in medical equipment, (catheters, endoscopes) and Micro-robots.
Diaphragm Pumps.
Namiki supplies diaphragm liquid and air pumps used in inkjet printers and biotechnology devices including incubation systems.
Vibration Components.
Namiki vibration motors and multi-functional vibration speakers combining speaker, receiver, and vibration functions, are used in mobile phones.


Harvey Hubbell

Harvey Hubbell II (December 20, 1857 – December 17, 1927), was an American inventor, entrepreneur, and industrialist. His best-known inventions are the U.S. electrical plug and the pull-chain light socket.
In 1888, at the age of thirty-one, Hubbell quit his job as a manager of a manufacturing company and founded Hubbell Incorporated in Bridgeport, Connecticut, a company which is still in business today, still headquartered near Bridgeport. Hubbell began manufacturing consumer products and, by necessity, inventing manufacturing equipment for his factory. Some of the equipment he designed included automatic tapping machines and progressive dies for blanking and stamping. One of his most important industrial inventions, still in use today, is the thread rolling machine. He quickly began selling his newly devised manufacturing equipment alongside his commercial products.
Hubbell received at least 45 patents, most of which were for electric products. The pull-chain electrical light socket was patented in 1896, and his most famous invention, the U.S. electrical power plug, in 1904. It allowed the adoption in the U.S. of convenient, portable electrical devices, which Great Britain had enjoyed since the early 1880s. In 1916, Hubbell was also granted a patent for a three-bladed power plug, including an earth pin, which Australian regulators and electrical accessory manufacturers adopted as the standard for that country in the 1930s. It was also adopted in New Zealand, Argentina, and (with a minor variation) in China.


Coil spring

The most common type of spring is the coil spring, which is made out of a long piece of metal that is wound around itself.
Coil springs were in use in Roman times, evidence of this can be found in bronze Fibulae — the clasps worn by Roman soldiers among others. These are quite commonly found in Roman archeological digs.
Coil springs can be either compression springs, tension springs or torsion springs, depending on how they are wound.
A coil spring is a mechanical device which is typically used to store energy and subsequently release it, to absorb shock, or to maintain a force between contacting surfaces. They are made of an elastic material formed into the shape of a helix which returns to its natural length when unloaded.
They are commonly used in mattresses, automotive suspensions, and residential plumbing. Coil springs come in a variety of sizes and shapes and can be used for a variety of applications. Small coil springs are often used in electronic devices, while larger ones are used in automobile suspensions. Coil springs can be made from various materials, including steel, brass, and bronze.
Spring rate.
Spring rate is the measurement of how much a coil spring can hold until it compresses . The manufacture normally specifies the spring rate. If a spring has a rate of 100 then the spring would compress 1 inch (2.54 cm)  with of load.
Types.
Types of coil spring are:
Heavy-duty springs.
Heavy-duty springs are designed to withstand high levels of force and tension. They are typically used in industrial and commercial applications where heavy loads need to be supported or generated. Heavy-duty springs can be made from various materials, including steel, stainless steel, and titanium. They are typically much stiffer and thicker than standard springs (3 mm — 65 mm thick) and can have a wide range of sizes and shapes. Because of their strength and durability, heavy-duty springs are typically used in automotive and mining applications. They are also commonly used in construction, motorsport, rail and other industries where heavy equipment is used.
Design.
Spring design must take into account the desired stiffness of the spring, as well as the amount of space that is available for the spring. In addition, springs must be designed to withstand the forces that will be applied to them, such as the car's weight or the gas pressure. Spring design is an important part of many engineering applications, and it is crucial to ensure that products work correctly and safely.
Applications.
Coil springs have many applications; notable ones include:
Coil springs are commonly used in vehicle suspension. These springs are compression springs and can differ greatly in strength and in size depending on application. A coil spring suspension can be stiff to soft depending on the vehicle it is used on. Coil spring can be either mounted with a shock absorber or mounted separately. Coil springs in trucks allow them to ride smoothly when unloaded, and once loaded the spring compresses and becomes stiff. This allows the vehicle to bounce less when loaded. Coil spring suspension is also used in high performance cars so that the car can absorb bumps and have low body roll. In off-road vehicles, they are used because of their range of travel they allow at the wheel.
Coil springs used in the engine are compression springs and play an important role in closing the valves that feed air and let exhaust gases out of the combustion chamber. The spring is attached to a rocker that is connected to the valve.
Tension and extension coil springs of a given material, wire diameter and coil diameter exert the same force when fully loaded; increased number of coils merely (linearly) increases free length and compressed/extended length.
Manufacture.
Metal coil springs are made by winding a wire around a shaped former a cylinder is used to form cylindrical coil springs.
Spring manufacture is the process of making springs by coiling, winding, or forming steel wire or other materials. Spring manufacturing includes various processes, including cold coiling and hot coiling.
To meet the demands of today's consumers, spring manufacturers must be able to produce springs in a wide range of sizes and shapes. As a result, spring manufacture has become increasingly complex and specialized. They must have a thorough understanding of spring design to produce quality products. In addition, they must be able to operate various machines to produce springs with the desired characteristics. Spring manufacture is a critical part of the economy, and spring makers play an important role in ensuring that products meet the highest quality standards.
Coil springs for vehicles are typically made of hardened steel. A machine called an auto-coiler takes spring wire that has been heated, so it can easily be shaped. It is then fed onto a lathe that has a metal rod with the desired coil spring size. The machine takes the wire and guides it onto the spinning rod, as well as pushing it across the rod to form multiple coils. The spring is then ejected from the machine and an operator will put it in oil to cool off. The spring is then tempered to lose the brittleness from being cooled. The coil size and strength can be controlled by the lathe rod size and material used. Different alloys are used to get certain characteristics out of the spring, such as stiffness, dampening, and strength.


Metal electrode leadless face

Metal electrode leadless face (MELF) is a type of leadless cylindrical electronic surface mount device that is metallized at its ends. MELF devices are usually diodes and resistors.
The EN 140401-803 and JEDEC DO-213 standards describe multiple MELF components.
Handling difficulties.
Because of their cylindrical shape and small size, in some cases these components can easily roll off the workbench or circuit board before they have been soldered into place. As such, there is a joke which suggests an alternate meaning for the acronym: "Most End up Lying on the Floor". Additionally, MELF components are sometimes called a "roll away" package.
During automated SMT pick-and-place, this happens mostly if the mechanical pressure of the SMD placer nozzle is too low. If the MELF components are placed into the solder paste with enough pressure, then this problem can be minimized. Care must be taken with glass diodes which are less mechanically robust than resistors and other MELF components.
Also, when building up PCBs via manual assembly using tweezers (e.g., for prototyping) then the pressure at the end of tweezers can often cause a MELF component to slip and shoot out the ends, thereby making their placement more difficult, compared to other flat component packages.
Another reason for the nickname of MELF components is that most production engineers do not like to use MELF nozzles on a SMT pick-and-place machine. For them it is waste of time to change from flat nozzles to MELF nozzles. For MICRO-MELF and MINI-MELF most SMD placers are able to use flat chip nozzles if the vacuum is high enough; i.e., higher than for flat chip components. For MELFs with the case size of 0207 or less, it is recommended to use the original MELF nozzle supplied with the SMT machine. Each supplier of such SMD pick-and-place machines offers these types of nozzles.
In order to overcome some of the difficulties encountered when mounting these devices, there are also variants with square electrodes (e.g. SQ MELF, QuadroMELF and B-MELF). These variants are mainly used in semiconductor diodes for applications where the high-reliability of hermetically sealed voidless-glass packages is required.
These handling difficulties prompted development of alternative SMT packages for common MELF components (like diodes) where the power handling capability needed to be similar to MELF components (superior to low-power 0805/0603, etc. SMT components) but with improved automated pick-and-place handling characteristics. This resulted in various squared-off packages with fold-over contacts, similar to rectangular inductor/tantalum capacitor packages.
Technical advantages.
Despite their handling difficulties, and in the particular case of MELF resistors, they are still widely used in high-reliability and precision applications where their predictable characteristics (e.g., low failure rate with well-defined failure modes) as well as their higher performance in terms of accuracy, long-term stability, moisture resistance, high-temperature operation far outweigh their disadvantages.


Spreader (lifting)

A spreader is a device used for lifting containers and unitized cargo. The spreader is placed between the container and the lifting machine.
The spreader used for containers has a locking mechanism at each corner that attaches to the four corners of the container. A spreader can be used on a container crane, a straddle carrier and with any other machinery to lift containers. Spreader operation can be manual, semiautomatic or fully automatic.


Injection molding machine

An injection molding machine (also spelled as injection moulding machine in BrE), also known as an injection press, is a machine for manufacturing plastic products by the injection molding process. It consists of two main parts, an "injection unit" and a "clamping unit".
Operation.
Injection molding machine molds can be fastened in either a horizontal or vertical position. Most machines are horizontally oriented, but vertical machines are used in some niche applications such as insert molding, allowing the machine to take advantage of gravity. Some vertical machines also do not require the mold to be fastened. There are many ways to fasten the tools to the platens, the most common are manual clamps (both halves are bolted to the platens); however, hydraulic clamps (chocks are used to hold the tool in place) and magnetic clamps are also used. The magnetic and hydraulic clamps are used where fast tool changes are required.
The person designing the mold chooses whether the mold uses a cold runner system or a hot runner system to carry the plastic and fillers from the injection unit to the cavities.
A cold runner is a simple channel carved into the mold.
The plastic that fills the cold runner cools as the part cools and is then ejected with the part as a sprue.
A hot runner system is more complicated, often using cartridge heaters to keep the plastic in the runners hot as the part cools.
After the part is ejected, the plastic remaining in a hot runner is injected into the next part.
Types of injection molding machines.
Machines are classified primarily by the type of driving systems they use: hydraulic, mechanical, electrical, or hybrid
Hydraulic.
Hydraulic machines have historically been the only option available to molders until Nissei Plastic Industrial introduced the first all-electric injection molding machine in 1983. Hydraulic machines, although not nearly as precise, are the predominant type in most of the world, with the exception of Japan.
Mechanical.
Mechanical type machines use the toggle system for building up tonnage on the clamps of the machine. Tonnage is required on all machines so that the clamps of the machine do not open due to the injection pressure. If the mold partially opens up, it will create flashing in the plastic product.
Electric.
The electric press, also known as Electric Machine Technology (EMT), reduces operation costs by cutting energy consumption and also addresses some of the environmental concerns surrounding the hydraulic press. Electric presses have been shown to be quieter, faster, and have a higher accuracy, however the machines are more expensive.
Hybrid injection (sometimes referred to as "Servo-Hydraulic") molding machines claim to take advantage of the best features of both hydraulic and electric systems, but in actuality use almost the same amount of electricity to operate as an electric injection molding machine depending on the manufacturer.
A robotic arm is often used to remove the molded components; either by side or top entry, but it is more common for parts to drop out of the mold, through a chute and into a container.
Main components of injection molding machine.
Injection unit.
Consists of three main components:
Clamping unit.
Consists of three main components:


Control arm

In automotive suspension, a control arm, also known as an A-arm, is a hinged suspension link between the chassis and the suspension upright or hub that carries the wheel. In simple terms, it governs a wheel's vertical travel, allowing it to move up or down when driving over bumps, into potholes, or otherwise reacting to the irregularities of a road surface. Most control arms form the lower link of a suspension. Control arms play a crucial role in the suspension system of a vehicle. They help to keep the wheels aligned and maintain proper tire contact with the road, which is essential for safety and stability.
The inboard (chassis) end of a control arm is attached by a single pivot, usually a rubber bushing. It can thus control the position of the outboard end in only a single degree of freedom, maintaining the radial distance from the inboard mount. Although not deliberately free to move, the single bushing does not control the arm from moving back and forth; this motion is constrained by a separate link or radius rod.
This is in contrast to the wishbone, which are triangular and have two widely spaced inboard bearings. These constrain the outboard end of the wishbone from moving back and forth, controlling two degrees of freedom, and without requiring additional links. Certain vehicles -- notably, many Honda products from the 1990s -- feature what's known as a double wishbone suspension. A double wishbone design features both upper and lower control arms that work in tandem with each other to properly locate the wheel. The additional radius rod is then attached to the upper arm.
MacPherson strut.
Control arms are most commonly encountered as part of the MacPherson strut independent front suspension. The control arms are perpendicular to the axis of the vehicle and are termed "track control arms". A diagonal "radius rod" constrains the strut from moving forward and back.
In MacPherson's original design, an anti-roll bar also acted as the radius rod. This requires the bar to be attached through a ball joint, so as to also provide longitudinal control. In most contemporary designs, still commonly termed MacPherson struts, the radius rod and anti-roll bar are now separate, with the anti-roll bar mounted in a sliding bush.
Spring attachment.
A control arm may be used to carry the suspension load and transmit them to the spring or shock absorber. Torsion bar suspension commonly does this, with the outboard end of the torsion bar attached to the inboard bearing of the control arm..


Metal injection molding

Metal injection molding (MIM) is a metalworking process in which finely-powdered metal is mixed with binder material to create a "feedstock" that is then shaped and solidified using injection molding. The molding process allows high volume, complex parts to be shaped in a single step. After molding, the part undergoes conditioning operations to remove the binder (debinding) and densify the powders. Finished products are small components used in many industries and applications.
The behavior of MIM feedstock is governed by rheology, the study of sludges, suspensions, and other non-Newtonian fluids.
Due to current equipment limitations, products must be molded using quantities of 100 grams or less per "shot" into the mold. This shot can be distributed into multiple cavities, making MIM cost-effective for small, intricate, high-volume products, which would otherwise be expensive to produce. MIM feedstock can be composed of a plethora of metals, but most common are stainless steels, widely used in powder metallurgy. After the initial molding, the feedstock binder is removed, and the metal particles are diffusion bonded and densified to achieve the desired strength properties. The latter operation typically shrinks the product by 15% in each dimension.
Adopted by a variety of industries MIM manufacturing is well-suited to produce medium to high volume components by increasing the number of mold cavities. Ideal candidates include those that weigh less than 100 grams, have complex geometries and tight tolerances, and can fit in the palm of your hand.
The metal injection molding market has grown from US$9 million in 1986, to US$382 million in 2004 to more than US$1.5 billion in 2015. A related technology is ceramic powder injection molding, leading to about US$2 billion total sales. Most of the growth in recent years has been in Asia.
Process.
In the monograph P.O. Gribovsky, published in 1956, describes in detail the technology of hot casting (hot molding) ceramic products under pressure (now, Low Pressure Powder Injection Molding) and, in particular, notes that "hot casting technology provides the ability to manufacture products from any solid materials, ranging from natural minerals, pure oxides, carbides, metals, etc., and ending with multicomponent composite synthetic materials and their combinations". This indication of the possibility of MIM-casting, which was implemented by Dr. Raymond E. Wiech Jr. in the 1970s, who refined MIM technology as co-founder of a California company named Parmatech, the name being condensed from the phrase "particle materials technology". Wiech later patented his process, and it was widely adopted for manufacturing use in the 1980s.
MIM gained recognition throughout the 1990s as improvements to subsequent conditioning processes resulted in an end product that performs similarly to or better than those made through competing processes. MIM technology improved cost efficiency through high volume production to "net-shape", negating costly, additional operations such as machining although MIM is weak in terms of tight dimensional specifications.
The process steps involve combining metal powders with polymers such as wax and polypropylene binders to produce the "feedstock" mix that is injected as a liquid into a mold using plastic injection molding machines. The molded or "green part" is cooled and ejected from the mold. Next, a portion of the binder material is removed using solvent, thermal furnaces, catalytic process, or a combination of methods. The resulting, fragile and porous (40 volume percent "air") part, is in a condition called the "brown" stage. To improve handling often the debinding and sintering are combined into a single process. Sintering heats the powder to temperatures near the melting point in a protective atmosphere furnace to densify the particles using capillary forces in a process called sintering. MIM parts are often sintered at temperatures nearly high enough to induce partial melting in a process termed liquid phase sintering. For example, a stainless steel might be heated to . Diffusion rates are high leading to high shrinkage and densification. If performed in vacuum, it is common to reach 96–99% solid density. The end-product metal has comparable mechanical and physical properties with annealed parts made using classic metalworking methods. Post sintering heat treatments for MIM are the same as with other fabrication routes, and with high density the MIM component is compatible with the metal conditioning treatments such as plating, passivating, annealing, carburizing, nitriding, and precipitation hardening.
Applications.
The window of economic advantage in metal injection molded parts lies in complexity and volume for small-size parts. MIM materials are comparable to metal formed by competing methods, and final products are used in a broad range of industrial, commercial, medical, dental, firearms, aerospace, and automotive applications. Dimensional tolerances of ±0.3% are common and machining is required for closer tolerances. MIM can produce parts where it is difficult, or even impossible, to efficiently manufacture an item through other means of fabrication. Ideally, at least 75 dimensional specifications in a component of just 25 mm maximum size and 10 g mass is best – as for example required for watch cases, cellular telephone plugs, and laptop computer hinges. Increased costs for traditional manufacturing methods inherent to part complexity, such as internal/external threads, miniaturization, or identity marking, typically do not increase the cost in a MIM operation due to the flexibility of injection molding.
Other design capabilities that can be implemented into the MIM operation include product codes, part numbers, or date stamps; parts manufactured to their net weight reducing material waste and cost; Density controlled to within 95–98%; Amalgamation of parts and Complex 3D Geometries.
The ability to combine several operations into one process ensures MIM is successful in saving lead times as well as costs, providing significant benefits to manufacturers. The metal injection molding process might be a green technology due to the significant reduction in wastage compared to "traditional" manufacturing methods such as 5 axis CNC machining. However, some of the older operations generate toxic emissions such as formaldehyde, dispose of chlorinated solvents, and must burn off wax or other polymers, leading to greenhouse gas emissions.
There is a broad range of materials available when utilizing the MIM process. Traditional metalworking processes often involve a significant amount of material waste, which makes MIM a highly efficient option for the fabrication of complex components consisting of expensive/special alloys (cobalt-chrome, 17-4 PH stainless steel, titanium alloys and tungsten carbides). MIM is a viable option when extremely thin walls specifications (i.e., 100 micrometers) are required. Additionally, electromagnetic interference shielding requirements have presented unique challenges, which are being successfully attained through the utilization of specialty alloys (ASTM A753 Type 4).
Disadvantages.
Although MIM has many advantages, it also has disadvantages:
See also.
Die casting


Hubs and nodes

Hubs and nodes is a geographic model explaining how linked regions can co-operate to fulfill elements of an industry's value chain and collectively gain sufficient mass to drive innovation growth. The model of hubs and nodes builds on Porter's cluster model which served well in the past, but as businesses and regions around the world have adjusted to the realities of globalization, the concept of clusters is becoming outdated.
Disaggregation of clusters.
Companies are realizing that they may not require a particular stage of production to be in close geographic proximity. As barriers to long-distance national and global transactions have fallen through advances in technology and logistics, such as the growth of the Internet and overnight package services, it has become increasingly possible to relocate operations such as research, product development, and manufacturing to countries and regions with relevant expertise and lower costs. It is common among consumer goods, for example, to have concept generation centered in one locale, product testing and refinement in another, and manufacturing and distribution in still others. Elements of development, production and distribution are being more and more completed beyond the borders of historical clusters.
As more companies progress beyond the cluster model, they increasingly expand and diversify their operations to locations where their investments will be most profitable. For companies adequately prepared for the rapid globalization process, their research and development, manufacturing and distribution stages fare better as these businesses are able to reduce their costs and potentially realizing new efficiencies and increased speeds of product development. The spirit of the cluster model may remain intact, and the various stages of production will still be shared by a number of different entities, but geographical proximity need no longer bind the entities together


Surface of revolution

A surface of revolution is a surface in Euclidean space created by rotating a curve (the "generatrix") one full revolution around an "axis of rotation" (normally not intersecting the generatrix, except at its endpoints).
The volume bounded by the surface created by this revolution is the "solid of revolution".
Examples of surfaces of revolution generated by a straight line are cylindrical and conical surfaces depending on whether or not the line is parallel to the axis. A circle that is rotated around any diameter generates a sphere of which it is then a great circle, and if the circle is rotated around an axis that does not intersect the interior of a circle, then it generates a torus which does not intersect itself (a ring torus).
Properties.
The sections of the surface of revolution made by planes through the axis are called "meridional sections". Any meridional section can be considered to be the generatrix in the plane determined by it and the axis.
The sections of the surface of revolution made by planes that are perpendicular to the axis are circles.
Some special cases of hyperboloids (of either one or two sheets) and elliptic paraboloids are surfaces of revolution. These may be identified as those quadratic surfaces all of whose cross sections perpendicular to the axis are circular.
Area formula.
If the curve is described by the parametric functions , with ranging over some interval , and the axis of revolution is the -axis, then the area is given by the integral
provided that is never negative between the endpoints and . This formula is the calculus equivalent of Pappus's centroid theorem. The quantity
comes from the Pythagorean theorem and represents a small segment of the arc of the curve, as in the arc length formula. The quantity is the path of (the centroid of) this small segment, as required by Pappus' theorem.
Likewise, when the axis of rotation is the -axis and provided that is never negative, the area is given by
If the continuous curve is described by the function , then the integral becomes
for revolution around the -axis, and
for revolution around the "y"-axis (provided ). These come from the above formula.
For example, the spherical surface with unit radius is generated by the curve , when ranges over . Its area is therefore
For the case of the spherical curve with radius , rotated about the -axis
A minimal surface of revolution is the surface of revolution of the curve between two given points which minimizes surface area. A basic problem in the calculus of variations is finding the curve between two points that produces this minimal surface of revolution.
There are only two minimal surfaces of revolution (surfaces of revolution which are also minimal surfaces): the plane and the catenoid.
Coordinate expressions.
A surface of revolution given by rotating a curve described by formula_8 around the x-axis may be most simply described by formula_9. This yields the parametrization in terms of formula_10 and formula_11 as formula_12. If instead we revolve the curve around the y-axis, then the curve is described by formula_13, yielding the expression formula_14 in terms of the parameters formula_10 and formula_11.
If x and y are defined in terms of a parameter formula_17, then we obtain a parametrization in terms of formula_17 and formula_11. If formula_10 and formula_21 are functions of formula_17, then the surface of revolution obtained by revolving the curve around the x-axis is described by formula_23, and the surface of revolution obtained by revolving the curve around the y-axis is described by formula_24.
Geodesics.
Meridians are always geodesics on a surface of revolution. Other geodesics are governed by Clairaut's relation.
Toroids.
A surface of revolution with a hole in, where the axis of revolution does not intersect the surface, is called a toroid. For example, when a rectangle is rotated around an axis parallel to one of its edges, then a hollow square-section ring is produced. If the revolved figure is a circle, then the object is called a torus.
Applications.
The use of surfaces of revolution is essential in many fields in physics and engineering. When certain objects are designed digitally, revolutions like these can be used to determine surface area without the use of measuring the length and radius of the object being designed.


Brazing

Brazing is a metal-joining process in which two or more metal items are joined together by melting and flowing a filler metal into the joint, with the filler metal having a lower melting point than the adjoining metal.
Brazing differs from welding in that it does not involve melting the work pieces. Brazing differs from soldering through the use of a higher temperature and much more closely fitted parts than when soldering. During the brazing process, the filler metal flows into the gap between close-fitting parts by capillary action. The filler metal is brought slightly above its melting (liquidus) temperature while protected by a suitable atmosphere, usually a flux. It then flows over the base metal (in a process known as wetting) and is then cooled to join the work pieces together. A major advantage of brazing is the ability to join the same or different metals with considerable strength.
Process.
Brazing has many advantages over other metal-joining techniques, such as welding. Since brazing does not melt the base metal of the joint, it allows much tighter control over tolerances and produces a clean joint without the need for secondary finishing. Additionally, dissimilar metals and non-metals (i.e. metalized ceramics) can be brazed. In general, brazing also produces less thermal distortion than welding due to the uniform heating of a brazed piece. Complex and multi-part assemblies can be brazed cost-effectively. Welded joints must sometimes be ground flush, a costly secondary operation that brazing does not require because it produces a clean joint. Another advantage is that the brazing can be coated or clad for protective purposes. Finally, brazing is easily adapted to mass production and it is easy to automate because the individual process parameters are less sensitive to variation.
One of the main disadvantages is the lack of joint strength as compared to a welded joint due to the softer filler metals used. The strength of the brazed joint is likely to be less than that of the base but greater than the filler metal. Another disadvantage is that brazed joints can be damaged under high service temperatures. Brazed joints require a high degree of base-metal cleanliness when done in an industrial setting. Some brazing applications require the use of adequate fluxing agents to control cleanliness. The joint color is often different from that of the base metal, creating an aesthetic disadvantage.
High-quality brazed joints require that parts be closely fitted with base metal surfaces exceptionally clean and free of oxides. In most cases, joint clearances of are recommended for the best capillary action and joint strength; in some brazing operations, however, it is not uncommon to have joint clearances around . Cleanliness of the brazing surfaces is also important, as any contamination can cause poor wetting (flow). The two main methods for cleaning parts, prior to brazing, are chemical cleaning and abrasive or mechanical cleaning. In the case of mechanical cleaning it is important to maintain the proper surface roughness, as wetting on a rough surface occurs much more readily than on a smooth surface of the same geometry.
Another consideration is the effect of temperature and time on the quality of brazed joints. As the temperature of the braze alloy is increased, the alloying and wetting action of the filler metal increases as well. In general, the brazing temperature selected must be above the melting point of the filler metal. However, several factors influence the joint designer's temperature selection. The best temperature is usually selected to:
In some cases, a worker may select a higher temperature to accommodate other factors in the design (e.g., to allow use of a different filler metal, or to control metallurgical effects, or to sufficiently remove surface contamination). The effect of time on the brazed joint primarily affects the extent to which these effects are present. In general, however, most production processes are selected to minimize brazing time and associated costs. This is not always the case, however, since in some non-production settings, time and cost are secondary to other joint attributes (e.g., strength, appearance).
Techniques.
There are many heating methods available to accomplish brazing operations. The most important factor in choosing a heating method is achieving efficient transfer of heat throughout the joint and doing so within the heat capacity of the individual base metals used. The geometry of the braze joint is also a crucial factor to consider, as is the rate and volume of production required. The easiest way to categorize brazing methods is to group them by heating method. Here are some of the most common:
These heating methods are classified through localised and diffuse heating techniques and offer advantages based on their different applications.
Torch brazing.
Torch brazing is by far the most common method of mechanized brazing in use. It is best used in small production volumes or in specialized operations, and in some countries, it accounts for a majority of the brazing taking place. There are three main categories of torch brazing in use: manual, machine, and automatic torch brazing.
"Manual torch brazing" is a procedure where the heat is applied using a gas flame placed on or near the joint being brazed. The torch can either be hand held or held in a fixed position depending on whether the operation is completely manual or has some level of automation. Manual brazing is most commonly used on small production volumes or in applications where the part size or configuration makes other brazing methods impossible. The main drawback is the high labor cost associated with the method as well as the operator skill required to obtain quality brazed joints. The use of flux or self-fluxing material is required to prevent oxidation. Torch brazing of copper can be done without the use of flux if it is brazed with a torch using oxygen and hydrogen gas, rather than oxygen and other flammable gases.
"Machine torch brazing" is commonly used where a repetitive braze operation is being carried out. This method is a mix of both automated and manual operations with an operator often placing brazes material, flux and jigging parts while the machine mechanism carries out the actual braze. The advantage of this method is that it reduces the high labor and skill requirement of manual brazing. The use of flux is also required for this method as there is no protective atmosphere, and it is best suited to small to medium production volumes.
"Automatic torch brazing" is a method that almost eliminates the need for manual labor in the brazing operation, except for loading and unloading of the machine. The main advantages of this method are: a high production rate, uniform braze quality, and reduced operating cost. The equipment used is essentially the same as that used for Machine torch brazing, with the main difference being that the machinery replaces the operator in the part preparation.
Furnace brazing.
Furnace brazing is a semi-automatic process used widely in industrial brazing operations due to its adaptability to mass production and use of unskilled labor. There are many advantages of furnace brazing over other heating methods that make it ideal for mass production. One main advantage is the ease with which it can produce large numbers of small parts that are easily jigged or self-locating. The process also offers the benefits of a controlled heat cycle (allowing use of parts that might distort under localized heating) and no need for post braze cleaning. Common atmospheres used include: inert, reducing or vacuum atmospheres all of which protect the part from oxidation. Some other advantages include: low unit cost when used in mass production, close temperature control, and the ability to braze multiple joints at once. Furnaces are typically heated using either electric, gas or oil depending on the type of furnace and application. However, some of the disadvantages of this method include: high capital equipment cost, more difficult design considerations and high power consumption.
There are four main types of furnaces used in brazing operations: batch type; continuous; retort with controlled atmosphere; and vacuum.
A "batch" type furnace has relatively low initial equipment costs, and can heat each part load separately. It can turned on and off at will, which reduces operating expenses when it's not in use. These furnaces are suited to medium to large volume production, and offer a large degree of flexibility in type of parts that can be brazed. Either controlled atmospheres or flux can be used to control oxidation and cleanliness of parts.
"Continuous type" furnaces are best suited to a steady flow of similar-sized parts through the furnace. These furnaces are often conveyor fed, moving parts through the hot zone at a controlled speed. It is common to use either controlled atmosphere or pre-applied flux in continuous furnaces. In particular, these furnaces offer the benefit of very low manual labor requirements and so are best suited to large scale production operations.
"Retort-type" furnaces differ from other batch-type furnaces in that they make use of a sealed lining called a "retort". The retort is generally sealed with either a gasket or is welded shut and filled completely with the desired atmosphere and then heated externally by conventional heating elements. Due to the high temperatures involved, the retort is usually made of heat resistant alloys that resist oxidation. Retort furnaces are often either used in a batch or semi-continuous versions.
"Vacuum furnaces" is a relatively economical method of oxide prevention and is most often used to braze materials with very stable oxides (aluminum, titanium and zirconium) that cannot be brazed in atmosphere furnaces. Vacuum brazing is also used heavily with refractory materials and other exotic alloy combinations unsuited to atmosphere furnaces. Due to the absence of flux or a reducing atmosphere, the part cleanliness is critical when brazing in a vacuum. The three main types of vacuum furnace are: single-wall hot retort, double-walled hot retort, and cold-wall retort. Typical vacuum levels for brazing range from pressures of 1.3 to 0.13 pascals (10−2 to 10−3 Torr) to 0.00013 Pa (10−6 Torr) or lower. Vacuum furnaces are most commonly batch-type, and they are suited to medium and high production volumes.
Silver brazing.
Silver brazing, sometimes known as hard soldering, is brazing using a silver alloy based filler. These silver alloys consist of many different percentages of silver and other metals, such as copper, zinc and cadmium.
Brazing is widely used in the tool industry to fasten "hard metal" (carbide, ceramics, cermet, and similar) tips to tools such as saw blades. "Pretinning" is often done: the braze alloy is melted onto the hard metal tip, which is placed next to the steel and remelted. Pretinning gets around the problem that hard metals are difficult to wet.
Brazed hard metal joints are typically two to seven mils thick. The braze alloy joins the materials and compensates for the difference in their expansion rates. It also provides a cushion between the hard carbide tip and the hard steel, which softens impact and prevents tip loss and damage—much as a vehicle's suspension helps prevent damage to the tires and the vehicle. Finally, the braze alloy joins the other two materials to create a composite structure, much as layers of wood and glue create plywood. The standard for braze joint strength in many industries is a joint that is stronger than either base material, so that when under stress, one or other of the base materials fails before the joint. Silver brazing may cause defects in certain alloys, e.g. stress-induced inter-granular cracking in copper-nickel.
One special silver brazing method is called ' or '. It has been developed especially for connecting cables to railway track or for cathodic protection installations. The method uses a silver- and flux-containing brazing pin, which is melted in the eye of a cable lug. The equipment is normally powered from batteries.
Braze welding.
"Braze welding" is the use of a bronze or brass filler rod coated with flux to join steel workpieces. The equipment needed for braze welding is basically identical to the equipment used in brazing. Since braze welding usually requires more heat than brazing, acetylene or methylacetylene-propadiene gas (MAPP gas) fuel is commonly used. The name comes from the fact that no capillary action is used.
Braze welding has many advantages over fusion welding. It allows the joining of dissimilar metals, minimization of heat distortion, and can reduce the need for extensive pre-heating. Additionally, since the metals joined are not melted in the process, the components retain their original shape; edges and contours are not eroded or changed by the formation of a fillet. Another effect of braze welding is the elimination of stored-up stresses that are often present in fusion welding. This is extremely important in the repair of large castings. The disadvantages are the loss of strength when subjected to high temperatures and the inability to withstand high stresses.
Carbide, cermet and ceramic tips are plated and then joined to steel to make tipped band saws. The plating acts as a braze alloy.
Cast iron "welding".
The "welding" of cast iron is usually a brazing operation, with a filler rod made chiefly of nickel being used although true welding with cast iron rods is also available.
Ductile cast iron pipe may be also "cadwelded," a process that connects joints by means of a small copper wire fused into the iron when previously ground down to the bare metal, parallel to the iron joints being formed as per hub pipe with neoprene gasket seals. The purpose behind this operation is to use electricity along the copper for keeping underground pipes warm in cold climates.
Vacuum brazing.
Vacuum brazing is a material joining technique that offers significant advantages: extremely clean, superior, flux-free braze joints of high integrity and strength. The process can be expensive because it must be performed inside a vacuum chamber vessel. Temperature uniformity is maintained on the work piece when heating in a vacuum, greatly reducing residual stresses due to slow heating and cooling cycles. This, in turn, can significantly improve the thermal and mechanical properties of the material, thus providing unique heat treatment capabilities. One such capability is heat-treating or age-hardening the workpiece while performing a metal-joining process, all in a single furnace thermal cycle.
Products that are most commonly vacuum-brazed include aluminum cold plates, plate-fin heat exchangers, and flat tube heat exchangers.
Vacuum brazing is often conducted in a furnace; this means that several joints can be made at once because the whole workpiece reaches the brazing temperature. The heat is transferred using radiation, as many other methods cannot be used in a vacuum.
Dip brazing.
Dip brazing is especially suited for brazing aluminium because air is excluded, thus preventing the formation of oxides. The parts to be joined are fixtured and the brazing compound applied to the mating surfaces, typically in slurry form. Then the assemblies are dipped into a bath of molten salt (typically NaCl, KCl and other compounds), which functions as both heat transfer medium and flux. Many dip brazed parts are used in heat transfer applications for the aerospace industry.
Filler materials.
A variety of alloys are used as filler metals for brazing depending on the intended use or application method. In general, braze alloys are composed of three or more metals to form an alloy with the desired properties. The filler metal for a particular application is chosen based on its ability to: wet the base metals, withstand the service conditions required, and melt at a lower temperature than the base metals or at a very specific temperature.
Braze alloy is generally available as rod, ribbon, powder, paste, cream, wire and preforms (such as stamped washers). Depending on the application, the filler material can be pre-placed at the desired location or applied during the heating cycle. For manual brazing, wire and rod forms are generally used as they are the easiest to apply while heating. In the case of furnace brazing, the alloy is usually placed beforehand since the process is usually highly automated. Some of the more common types of filler metals used are
Some brazes come in the form of "trifoils", laminated foils of a carrier metal clad with a layer of braze at each side. The center metal is often copper; its role is to act as a carrier for the alloy, to absorb mechanical stresses due to e.g. differential thermal expansion of dissimilar materials (e.g. a carbide tip and a steel holder), and to act as a diffusion barrier (e.g. to stop diffusion of aluminium from aluminium bronze to steel when brazing these two).
Brazing alloys form several distinct groups; the alloys in the same group have similar properties and uses.
Some additives and impurities act at very low levels. Both positive and negative effects can be observed. Strontium at levels of 0.01% refines grain structure of aluminium. Beryllium and bismuth at similar levels help disrupt the passivation layer of aluminium oxide and promote wetting. Carbon at 0.1% impairs corrosion resistance of nickel alloys. Aluminium can embrittle mild steel at 0.001%, phosphorus at 0.01%.
In some cases, especially for vacuum brazing, high-purity metals and alloys are used. 99.99% and 99.999% purity levels are available commercially.
Care must be taken to not introduce deleterious impurities from joint contamination or by dissolution of the base metals during brazing.
Melting behavior.
Alloys with larger span of solidus/liquidus temperatures tend to melt through a "mushy" state, during which the alloy is a mixture of solid and liquid material. Some alloys show tendency to liquation, separation of the liquid from the solid portion; for these the heating through the melting range must be sufficiently fast to avoid this effect. Some alloys show extended plastic range, when only a small portion of the alloy is liquid and most of the material melts at the upper temperature range; these are suitable for bridging large gaps and for forming fillets. Highly fluid alloys are suitable for penetrating deep into narrow gaps and for brazing tight joints with narrow tolerances but are not suitable for filling larger gaps. Alloys with wider melting range are less sensitive to non-uniform clearances.
When the brazing temperature is suitably high, brazing and heat treatment can be done in a single operation simultaneously.
Eutectic alloys melt at single temperature, without mushy region. Eutectic alloys have superior spreading; non-eutectics in the mushy region have high viscosity and at the same time attack the base metal, with correspondingly lower spreading force. Fine grain size gives eutectics both increased strength and increased ductility. Highly accurate melting temperature lets joining process be performed only slightly above the alloy's melting point. On solidifying, there is no mushy state where the alloy appears solid but is not yet; the chance of disturbing the joint by manipulation in such state is reduced (assuming the alloy did not significantly change its properties by dissolving the base metal). Eutectic behavior is especially beneficial for solders.
Metals with fine grain structure before melting provide superior wetting to metals with large grains. Alloying additives (e.g. strontium to aluminium) can be added to refine grain structure, and the preforms or foils can be prepared by rapid quenching. Very rapid quenching may provide amorphous metal structure, which possess further advantages.
Interaction with base metals.
For successful wetting, the base metal must be at least partially soluble in at least one component of the brazing alloy. The molten alloy therefore tends to attack the base metal and dissolve it, slightly changing its composition in the process. The composition change is reflected in the change of the alloy's melting point and the corresponding change of fluidity. For example, some alloys dissolve both silver and copper; dissolved silver lowers their melting point and increases fluidity, copper has the opposite effect.
The melting point change can be exploited. As the remelt temperature can be increased by enriching the alloy with dissolved base metal, step brazing using the same braze can be possible.
Alloys that do not significantly attack the base metals are more suitable for brazing thin sections.
Nonhomogenous microstructure of the braze may cause non-uniform melting and localized erosions of the base metal.
Wetting of base metals can be improved by adding a suitable metal to the alloy. Tin facilitates wetting of iron, nickel, and many other alloys. Copper wets ferrous metals that silver does not attack, copper-silver alloys can therefore braze steels silver alone won't wet. Zinc improves wetting of ferrous metals, indium as well. Aluminium improves wetting of aluminium alloys. For wetting of ceramics, reactive metals capable of forming chemical compounds with the ceramic (e.g. titanium, vanadium, zirconium...) can be added to the braze.
Dissolution of base metals can cause detrimental changes in the brazing alloy. For example, aluminium dissolved from aluminium bronzes can embrittle the braze; addition of nickel to the braze can offset this.
The effect works both ways; there can be detrimental interactions between the braze alloy and the base metal. Presence of phosphorus in the braze alloy leads to formation of brittle phosphides of iron and nickel, phosphorus-containing alloys are therefore unsuitable for brazing nickel and ferrous alloys. Boron tends to diffuse into the base metals, especially along the grain boundaries, and may form brittle borides. Carbon can negatively influence some steels.
Care must be taken to avoid galvanic corrosion between the braze and the base metal, and especially between dissimilar base metals being brazed together. Formation of brittle intermetallic compounds on the alloy interface can cause joint failure. This is discussed more in-depth with solders.
The potentially detrimental phases may be distributed evenly through the volume of the alloy, or be concentrated on the braze-base interface. A thick layer of interfacial intermetallics is usually considered detrimental due to its commonly low fracture toughness and other sub-par mechanical properties. In some situations, e.g. die attaching, it however does not matter much as silicon chips are not typically subjected to mechanical abuse.
On wetting, brazes may liberate elements from the base metal. For example, aluminium-silicon braze wets silicon nitride, dissociates the surface so it can react with silicon, and liberates nitrogen, which may create voids along the joint interface and lower its strength. Titanium-containing nickel-gold braze wets silicon nitride and reacts with its surface, forming titanium nitride and liberating silicon; silicon then forms brittle nickel silicides and eutectic gold-silicon phase; the resulting joint is weak and melts at much lower temperature than may be expected.
Metals may diffuse from one base alloy to the other one, causing embrittlement or corrosion. An example is diffusion of aluminium from aluminium bronze to a ferrous alloy when joining these. A diffusion barrier, e.g. a copper layer (e.g. in a trimet strip), can be used.
A sacrificial layer of a noble metal can be used on the base metal as an oxygen barrier, preventing formation of oxides and facilitating fluxless brazing. During brazing, the noble metal layer dissolves in the filler metal. Copper or nickel plating of stainless steels performs the same function.
In brazing copper, a reducing atmosphere (or even a reducing flame) may react with the oxygen residues in the metal, which are present as cuprous oxide inclusions, and cause hydrogen embrittlement. The hydrogen present in the flame or atmosphere at high temperature reacts with the oxide, yielding metallic copper and water vapour, steam. The steam bubbles exert high pressure in the metal structure, leading to cracks and joint porosity. Oxygen-free copper is not sensitive to this effect, however the most readily available grades, e.g. electrolytic copper or high-conductivity copper, are. The embrittled joint may then fail catastrophically without any previous sign of deformation or deterioration.
Flux.
Unless brazing operations are contained within an inert or reducing atmosphere environment (i.e. Nitrogen), a flux such as borax is required to prevent oxides from forming while the metal is heated. The flux also serves the purpose of cleaning any contamination left on the brazing surfaces. Flux can be applied in any number of forms including flux paste, liquid, powder or pre-made brazing pastes that combine flux with filler metal powder. Flux can also be applied using brazing rods with a coating of flux, or a flux core. In either case, the flux flows into the joint when applied to the heated joint and is displaced by the molten filler metal entering the joint. Excess flux should be removed when the cycle is completed because flux left in the joint can lead to corrosion, impede joint inspection, and prevent further surface finishing operations. Phosphorus-containing brazing alloys can be self-fluxing when joining copper to copper. Fluxes are generally selected based on their performance on particular base metals. To be effective, the flux must be chemically compatible with both the base metal and the filler metal being used. Self-fluxing phosphorus filler alloys produce brittle phosphides if used on iron or nickel. As a general rule, longer brazing cycles should use less active fluxes than short brazing operations.
Atmosphere.
As brazing work requires high temperatures, oxidation of the metal surface occurs in an oxygen-containing atmosphere. This may necessitate the use of an atmospheric environment other than air. The commonly used atmospheres are:
Preforms.
A brazing preform is a high quality, precision metal stamping used for a variety of joining applications in manufacturing electronic devices and systems. Typical brazing preform uses include attaching electronic circuitry, packaging electronic devices, providing good thermal and electrical conductivity, and providing an interface for electronic connections. Square, rectangular and disc shaped brazing preforms are commonly used to attach electronic components containing silicon dies to a substrate such as a printed circuit board. Rectangular frame shaped preforms are often required for the construction of electronic packages while washer shaped brazing preforms are typically utilized to attach lead wires and hermetic feed-throughs to electronic circuits and packages. Some preforms are also used in diodes, rectifiers, optoelectronic devices and components packaging.
Safety.
Brazing may entail exposure to hazardous chemical fumes. The National Institute for Occupational Safety and Health in the United States recommends that exposure to these fumes is controlled to levels below the allowed exposure limit.


Transfer stamping

Sheet metal forming in medium-high volume production environments is often completed through the use of a Transfer Press operating a number of dies as a complete system. Each die in the system is responsible for adding more shape to the part until the metal work piece attains its final shape. What makes transfer stamping unique is that a single press operates a number of tools, the movement of the sheet metal work piece from one operation to the next is performed by automation either built into the press or onto the dies. With each closing of the press the entire system of tools will close, each performing its designed work to the sheet metal. Upon opening the built in transfer mechanism moves the workpiece from one operation to the next in the sequence.
In the past these operations may have been performed using individual presses and the workpieces may have been moved from press to press, and die to die, by hand. As Automation improved hand loading was replaced by pick and place automation and by robots. The transfer press is a natural extension of this practice, simplifying the operation by having all tools in a single large press and using automation which is specifically designed for the press operations.
Transfer mechanisms.
Tri-axis transfer.
Named for the movement of the transfer mechanism, tri-axis transfer mechanisms motion is defined by the three (3) axes of movement made by the part manipulators each press stroke. On the press downstroke the automation which will likely be holding the work piece will lower the work piece to the tool and retract to leave the part on the tool. At the bottom of the stroke the automation mechanism in the retracted state will cycle backward one pitch to position itself adjacent to the next workpiece. As the press cycles upward the part manipulators will index inward to pick up the next work piece, continuing upward following the press ram, then indexing forward to next station. As the press reaches the top of its stroke, the process repeats. The three axes of motion are up-down, in-out, and forward-back.
Cross-bar transfer.
With a cross bar transfer mechanism, the in-out axes of movement is constrained by an automation bar spanning the die space. Commonly mounted with suction cups, this cross bar will pick the workpiece up from above and release the part, dropping it into place at the next station. With only two axes of motion and the automation spanning the die space, the cross bar transfer mechanism must "dwell" between adjacent tools between each press stroke.


Kudo3d

Kudo3D, based in Dublin, California, manufactures professional desktop 3D printers. Its Titan 1 and Titan 2 3D printer use a proprietary passive self-peeling technology, making it one of the leading professional high-resolution stereolithography printers. This technology allows both the Titan 1 and Titan 2 to be used in printing for various applications.
History.
In 2012, founder Tedd Syao started creating the Titan 1 and developed the passive self-peeling technology from his garage. Shortly after, Tedd Syao and Jonathan Cheung, both UC Berkeley's Haas School of Business alumni, co-founded Kudo3D.
Kudo3D launched its Kickstarter in May 2014 that was funded within 2 minutes. After its successful campaign and delivery, Kudo3D continued to grow. The company has now expanded to two locations: Pleasanton, California, and Hsinchu, Taiwan.
Titan 1.
The Titan 1 was constructed using modular design, utilizing industrial and consumer-grade components. The printer uses Texas Instrument's DLP technology as its light source and printing time is further reduced as entire layers of resin can be cured at one time. Other components include an industrial grade linear stage module, an open-source controlling circuit, a stepping motor, a fast leveling build platform, and Kudo3D's patented flexible PSP (Passive self-peeling) resin container lined with Teflon to extend container lifetime.
Third Party Resin.
The Titan 1 prints using third party resin. Titan 1 is most compatible with: MakerJuice G+, Spot A's Hard & Tough for High Resolution, Spot A's Flexible Resin, 3D Materials’ Castable and ABS resins.
Application.
The Titan 1's ability to print a wide range of sizes makes it versatile and usable for different applications. The Titan 1 grows extremely high resolutions prints, which is ideal for printing jewelry, miniatures, and research models. The Titan 1 has printed tissue scaffold for the biomedical research department at CCNY that is only 1mm by 2mm. However, it also possesses the ability to print larger items, making the Titan 1 perfect for art, architectural, engineering, and prototyping applications.
Titan 2.
2 years after the successful Kickstarter campaign, Kudo3D released their second generation 3D printer, the Titan 2. The Titan 2 promises a more reliable 3D printer with advanced controls, making it more user-friendly than its predecessor. With a built-in Raspberry Pi and web-based controls, the Titan 2 is compatible with any computer, tablet, or smartphone device.
The Titan 2 incorporates all of the technology from the Titan 1, including the patented PSP resin container. In addition, the Titan 2 comes in 2 different cover colors, the Ruby Red and Green Emerald.
Titan 2 HR.
In November 2016, Kudo3D released a "spin-off" of the Titan 2 3D printer. Named Titan 2 HR, this printer is capable of printing objects at 23 microns XY resolution. This capability makes it especially appealing to people who would like to print high-resolution, fine prints, such as jewelers.
Bean.
Marking the third anniversary of the initial Kickstarter launch, Kudo3D launched their new printer once again on Kickstarter. Dubbed the Bean, this compact 3D printer was created to solve the consumer's desire for a high resolution, low cost 3D printer. The Bean was able to reach their goal of $50,000 within 2 minutes and $100,000 in 3 minutes. The Bean 3D printer is a LCD SLA 3D printer, meaning it uses a LCD to project images slices onto the resin container.
Kudo3d offers seven proprietary resins (not compatible with Titan 1 or Titan 2) for the Bean; It can also use third party resins.
PSP Technology.
Passive self-peeling (PSP) technology is a patented, bottom-up, SLA technology, which was created by Kudo3D to minimize the separation force between the cured layers and the resin. PSP employs a flexible resin container consisting of 5 different materials, which work together to aid in reducing the separation force. It ensures that features as fine as a strand of hair and larger objects, up to 10 inches tall, can be printed with the same machine.
This technology allows prints to require fewer supports, minimizing cleanup and scarring. It also enables features as fine as a strand of hair and larger objects, up to 10 inches tall, to be printed by the same machine while maintaining staggering resolution and impressive speeds.
Patent Approval.
On September 27, 2016, Kudo3D received approval of the PSP (passive self-peeling) technology from the US Patent and Trademark Office.


High stock removal

High stock removal is a technological process with the goal of removing large amounts of material. The quantity of material which can be removed by a specific process depends on the material properties and the machining tool used.
Materials.
The stock removal rate is largely a function of the material's properties. This is expressed as the machinability of a material: the ease or difficulty of machining a particular material. The machinability of materials varies greatly; for instance, aluminium and magnesium have high machinability compared to titanium and other special metals.
Specific energy.
One way of quantifying the machinability of a material is to measure specific energy (e): this is the amount of energy required to cut a given volume of work material (kWh/mm3), and varies with material properties.
New materials.
New materials are continuously developed to address the extreme demands of market segments such as petrochemical and aerospace. Metallurgical advances have produced a wide range of high-performance materials (e.g. titanium and high-nickel alloys), but a consequence of their attractive properties is often that they are difficult to machine.
Temperature rising.
The specific cutting energy needed for ‘difficult to machine’ materials can be extremely high. Especially in high stock removal applications, there are problems with thermal load in the work material. An increase of the work material temperature can lead to deterioration of the work material surface integrity, resulting in metallurgical damages like micro-cracks, residual stresses and work hardening. Excessive heat also dramatically shortens tool life.
High stock removal machine tools.
The energy required to remove large amounts of material depends on the properties of the working material (specific energy) as well as the technological process used.
Technologies.
Several technologies are capable of removing substantial amounts of material. Among them are: sawing, turning, broaching, milling and grinding. Turning and milling are the most popular machining technologies; turning is mainly used for round products (though a specialized variant called whirling can modulate the turning axis to produce non-round shapes), whereas milling has a broad range of applications. Certain ‘difficult to machine’ materials like titanium, stainless steels, and exotic high-nickel alloys can be challenging to process when high stock removal is the goal, due to local heat generation at the cutting edge and the difficulty in removing it. These challenges can be mitigated, however, by strategies such as high-volume flood coolant, specialized cutting tool geometries, optimized speed and feed settings, and tool coatings like AlTiCN which tend to divert heat into the chip, away from the cutting tool.
Grinding.
Traditionally bonded abrasives are used for stock removal. To remove substantial amounts of material in a grinding process, vertical segment grinders are used. These machines work with a rotating disc with abrasive segments, against which the work material is pressed with the aid of a rotating or reciprocating table. These technologies require significantly greater power than other grinding methods, up to . Some major manufactures of these machines are Blanchard, Mattison, Göckel and Reform.
Belt grinding.
Grinding with coated abrasives has recently become a viable alternative for high stock removal through developments in machine tool and grinding belt technology.
Belt grinding with coated abrasives can be an attractive process because the large surface area of the recirculating belt tends to carry away heat and prevent local hot spots. The productivity of this technology is, in many cases, three times that of rotary or reciprocating vertical grinders. As a result, belt grinding is replacing traditional grinding technologies in the field of the specialty metal processing.


Belt grinding

Belt grinding is an abrasive machining process used on metals and other materials. It is typically used as a finishing process in industry. A belt, coated in abrasive material, is run over the surface to be processed in order to remove material or produce the desired finish.
Applications.
Belt grinding is a versatile process suitable for all kinds of different applications. There are three different applications of the belt grinding technology:
Grinding methods.
Wide belt grinding is a familiar process in industry as well as home applications. There are several basic methods for belt grinding:
In general there are three basic elements of the belt-grinding machine: work rest support, grinding head and a regulating head. These components differ for all the methods but in general the workpiece is pressed between the grinding head and the rest support. The objective of the regulating head is to coordinate the belt pressure.
Wide belt grinding.
One of the most common methods is wide belt grinding.
The belt grinding process is variable by adjusting certain parameters such as belt speed, grinding pressure, feed speed, durometer of the contact drum, size of the contact drum and the abrasive belt that is used. The machines can be made for wet or dry operation. Furthermore, a wide belt grinding machine can be constructed with single or multiple heads. The first head is used for coarse grinding and the next heads gradually make a finer finish. Wide belt grinding is also used as a high stock removal method for special metals (e.g. stainless steel, titanium, and nickel alloys).
Changing variables.
There are several objectives possible for grinding with coated abrasives. Among them are the right application (e.g. finish or stock removal), time saving and efficiency of the abrasive tool.
To achieve the above objectives, it is essential to look in more detail to the variables which affect them. These include the work material properties, the grit and abrasive type of the grinding belt, belt speed, belt sequences, contact wheel hardness and diameter, serration, type of lubricant (or dry) and grinding pressure. Changing these variables will affect the performances of the belt grinding process.
In the wide belt method, a contact wheel supports the abrasive belt. The selection of the contact wheel and abrasive to match the grinding parameters required for a specific operation is very critical. Stock removal generally requires a harder, serrated rubber contact wheel, and coarse grade ceramic abrasives. Finishing generally requires the use of a smooth faced contact wheel and fine grade abrasives.


Fusible core injection molding

Fusible core injection molding, also known as lost core injection molding, is a specialized plastic injection molding process used to mold internal cavities or undercuts that are not possible to mold with demoldable cores. Strictly speaking the term "fusible core injection molding" refers to the use of a fusible alloy as the core material; when the core material is made from a soluble plastic the process is known as soluble core injection molding. This process is often used for automotive parts, such as intake manifolds and brake housings, however it is also used for aerospace parts, plumbing parts, bicycle wheels, and footwear.
The most common molding materials are glass-filled nylon 6 and nylon 66. Other materials include unfilled nylons, polyphenylene sulfide, glass-filled polyaryletherketone (PAEK), glass-filled polypropylene (PP), rigid thermoplastic urethane, and elastomeric thermoplastic polyurethane.
History.
The first patent for this type of molding process was taken out in 1968, however it was rarely used until the 1980s. That is when the automotive industry took interest in it to develop intake manifolds.
Process.
The process consists of three major steps: casting or molding a core, inserting the core into the mold and shooting the mold, and finally removing the molding and melting out the core.
Core.
First, a core is molded or die cast in the shape of the cavity specified for the molded component. It can be made from a low melting point metal, such as a tin-bismuth alloy, or a polymer, such as a soluble acrylate. The polymer has approximately the same melting temperature as the alloy, however the alloy ratios can be modified to alter the melting point. Another advantage to using a metal core is that multiple smaller cores can be cast with mating plugs and holes so they can be assembled into a final large core.
One key in casting metal cores is to make sure they do not contain any porosity as it will induce flaws into the molded part. In order to minimize porosity the metal may be gravity cast or the molding cavity may be pressurized. Another system slowly rocks the casting dies as the molding cavity fills to "shake" the air bubbles out.
The metal cores can be made from a number of low melting point alloys, with the most common being a mixture of 58% bismuth and 42% tin, which is used for molding nylon 66. One of the main reasons it is used is because it expands as it cools which packs the mold well. Other alloys include tin-lead-silver alloys and tin-lead-antimony alloys. Between these three alloy groups a melting point between 98 and 800 °F (37–425 °C) can be achieved.
Polymer cores are not as common as metal cores and are usually only used for moldings that require simple internal surface details. They are usually thick hollow cross-sections that are molded in two halves and are ultrasonically welded together. Their greatest advantage is that they can be molded in traditional injection molding machines that the company already has instead of investing into new die casting equipment and learning how to use it. Because of this polymer core materials are most adventitious for small production runs that cannot justify the added expense of metal cores. Unfortunately it is not as recyclable as the metal alloys used in cores, because 10% new material must be added with the recycled material.
Molding.
In the second step, the core is then inserted into the mold. For simple molds this is as simple as inserting the core and closing the dies. However, more complex tools require multiple steps from the programmed robot. For instance, some complex tools can have multiple conventional side pulls that mate with the core to add rigidity to the core and reduce the core mass. After the core is loaded and the press closed the plastic is shot.
Melt-out.
In the final step, the molded component and core are both demolded and the core is "melted-out" from the molding. This is done in a "hot bath", via induction heating, or through a combination of the two. Hot baths usually use a tub filled with glycol or Lutron, which is a phenol-based liquid. The bath temperature is slightly higher than that of the core alloy’s melting point, but not so high that it damages the molding. In typical commercial applications the parts are dipped into the hot bath via an overhead conveyor. The advantage to using a hot bath is that it is simpler than induction heating and it helps cure thermoset moldings. The disadvantage is that it is uneconomically slow at a cycle time of 60 to 90 minutes and it poses environmental cleanup issues. Typically the hot bath solution needs cleaning or replacement every year or every half year when used in combination with induction heating.
For thermoplastic moldings induction heating of the core metal is required, otherwise the prolonged heat from a hot bath can warp it. Induction heating reduces the melt-out time to one to three minutes. The disadvantage is that induction heating does not remove all of the core material so it must then be finished off in a hot bath or be brushed out. Another disadvantage is that the induction coils must be custom built for each molding because the coils must be from the part. Finally, induction heating systems cannot be used with moldings that have brass or steel inserts because the induction heating process can destroy or oxidize the insert.
For complex parts it can be difficult to get all of the core liquid to drain out in either melt-out process. In order to overcome this the parts may be rotated for up to an hour. Liquid core metal collects on the bottom of the heated bath and is usable for a new core.
Equipment.
Traditional horizontal injection molding machines have been used since the mid-1980s, however loading and unloading cores are difficult so two robots are required. Moreover, the cycle time is quite long, approximately 28 seconds. These problem are overcome by using rotary or shuttle action injection molding machines. These types of machines only require one robot to load and unload cores and have a 30% shorter cycle time. However, these types of machines cost approximately 35% more than horizontal machines, require more space, and require two bottom molds (because one is in the machine during the cycle and the other is being unloaded and loaded with a new core), which adds approximately 40% to the tooling cost. For small parts, horizontal injection molding machines are still used, because the core does not weigh enough to justify the use of a rotary machine.
For four-cylinder manifolds a 500-ton press is required; for a six- to eight-cylinder manifold a 600- to 800-ton press is required.
Advantages and disadvantages.
The greatest advantage of this process is its ability to produce single-piece injection moldings with highly complex interior geometries without secondary operations. Similarly shaped objects are usually made from aluminum castings, which can weigh 45% to 75% more than a comparable molding. The tooling also lasts longer than metal casting tooling due to the lack of chemical corrosion and wear. Other advantages include:
Two of the major disadvantages of this process are the high cost and long development time. An automotive part can take four years to develop; two years in the prototype stage and two years to reach production. Not all products take this long, for instance a two-way valve produced by Johnson Controls only took 18 months. The initial cost can be as much as US$8 million to produce a four-cylinder engine manifold. However, computer flow analysis has helped reduce lead time and costs.
One of the difficulties that result from these long development times and high costs is making accurate cores repeatably. This is extremely important because the core is an integral part of the mold, so essentially each shot is into a new mold cavity. Another difficulty is keeping the core from melting when the plastic is shot into the mold, because the plastic is approximately twice the melting temperature of the core material. A third difficulty is the low strength of the core. Hollow plastic cores can collapse if too much pressure is used in the shot plastic. Metal cores (with low melting temperatures) are solid so they cannot collapse, but are only 10% as strong as steel cores so they can distort. This is especially a problem when molding manifolds, because the waviness of the core can be detrimental to the airflow within the runners.
Another disadvantage is the need for a large space to house the injection molding machines, casting machines, melt-out equipment, and robots.
Because of these disadvantages, some moldings that would be made via this process are instead made by injection molding two or more parts in a traditional injection molding machine and then welding them together. This process is less expensive and requires much less capital, however it imparts more design constraints. Because of the design constraints, sometimes parts are made with both processes to gain the advantages of both.
Application.
The application of the fusible core process is not limited just to the injection of thermoplastics, but with corresponding core alloys also to thermosetting plastic molding materials (duroplast). The fusible core process finds application, for example, for injection molded passenger car engine intake manifolds. By modifying the equipment, small molded parts like valves or pump housings can be manufactured, as the manufacture of the fusible cores and the injected parts can be carried out on an injection molding machine.