Whisker (metallurgy)

Metal whiskering is a phenomenon which occurs in electrical devices when metals form long whisker-like projections over time. Tin whiskers were noticed and documented in the vacuum tube era of electronics early in the 20th century in equipment that used pure, or almost pure, tin solder in their production. It was noticed that small metal hairs or tendrils grew between metal solder pads, causing short circuits. Metal whiskers form in the presence of compressive stress. Germanium, zinc, cadmium, and even lead whiskers have been documented. Many techniques are used to mitigate the problem, including changes to the annealing process (heating and cooling), the addition of elements like copper and nickel, and the inclusion of conformal coatings. Traditionally, lead has been added to slow down whisker growth in tin-based solders.
Following the Restriction of Hazardous Substances Directive (RoHS), the European Union banned the use of lead in most consumer electronic products from 2006 due to health problems associated with lead and the "high-tech trash" problem, leading to a re-focusing on the issue of whisker formation in lead-free solders.
Mechanism.
Metal whiskering is a crystalline metallurgical phenomenon involving the spontaneous growth of tiny, filiform hairs from a metallic surface. The effect is primarily seen on elemental metals but also occurs with alloys.
The mechanism behind metal whisker growth is not well understood, but seems to be encouraged by compressive mechanical stresses including:
Metal whiskers differ from metallic dendrites in several respects: dendrites are fern-shaped and grow across the surface of the metal, while metal whiskers are hair-like and project normal to the surface. Dendrite growth requires moisture capable of dissolving the metal into a solution of metal ions, which are then redistributed by electromigration in the presence of an electromagnetic field. While the precise mechanism for whisker formation remains unknown, it is known that whisker formation does not require either dissolution of the metal or the presence of an electromagnetic field.
Effects.
Whiskers can cause short circuits and arcing in electrical equipment. The phenomenon was discovered by telephone companies in the late 1940s and it was later found that the addition of lead to tin solder provided mitigation. The European Restriction of Hazardous Substances Directive (RoHS), which took effect on July 1, 2006, restricted the use of lead in various types of electronic and electrical equipment. This has driven the use of lead-free alloys with a focus on preventing whisker formation . Others have focused on the development of oxygen-barrier coatings to prevent whisker formation.
Airborne zinc whiskers have been responsible for increased system failure rates in computer server rooms. Zinc whiskers grow from galvanized (electroplated) metal surfaces at a rate of up to a millimeter per year with a diameter of a few micrometers. Whiskers can form on the underside of zinc electroplated floor tiles on raised floors. These whiskers can then become airborne within the floor plenum when the tiles are disturbed, usually during maintenance. Whiskers can be small enough to pass through air filters and can settle inside equipment, resulting in short circuits and system failure.
Tin whiskers do not have to be airborne to damage equipment, as they are typically already growing directly in the environment where they can produce short circuits, i.e., the electronic equipment itself. At frequencies above 6 GHz or in fast digital circuits, tin whiskers can act like miniature antennas, affecting the circuit impedance and causing reflections. In computer disk drives they can break off and cause head crashes or bearing failures. Tin whiskers often cause failures in relays and have been found upon examination of failed relays in nuclear power facilities. Pacemakers have been recalled due to tin whiskers. Research has also identified a particular failure mode for tin whiskers in vacuum (such as in space), where in high-power components a short-circuiting tin whisker is ionized into a plasma that is capable of conducting hundreds of amperes of current, massively increasing the damaging effect of the short circuit. The possible increase in the use of pure tin in electronics due to the RoHS directive drove JEDEC and IPC to release a tin whisker acceptance testing standard and mitigation practices guideline intended to help manufacturers reduce the risk of tin whiskers in lead-free products.
Silver whiskers often appear in conjunction with a layer of silver sulfide, which forms on the surface of silver electrical contacts operating in an atmosphere rich in hydrogen sulfide and high humidity. Such atmospheres can exist in sewage treatment plants and paper mills.
Whiskers over 20 µm in length were observed on gold-plated surfaces and noted in a 2003 NASA internal memorandum.
The effects of metal whiskering were chronicled on History Channel's program "Engineering Disasters" 19.
Mitigation and elimination.
Several approaches are used to reduce or eliminate whisker growth, with ongoing research in the area.
Conformal coatings.
Conformal compound coatings stop the whiskers from penetrating a barrier, reaching a nearby termination and forming a short.
Altering plating chemistry.
Termination finishes of nickel, gold or palladium have been shown to eliminate whisker formation in controlled trials.
Tin whisker examples and incidents.
Galaxy IV.
Galaxy IV was a telecommunications satellite that was disabled and lost due to short circuits caused by tin whiskers in 1998. It was initially thought that space weather contributed to the failure, but later it was discovered that a conformal coating had been misapplied, allowing whiskers formed in the pure tin plating to find their way through a missing coating area, causing a failure of the main control computer. The manufacturer, Hughes, has moved to nickel plating, rather than tin, to reduce the risk of whisker growth. The trade-off has been an increase in weight, adding per payload.
Millstone Nuclear Power Plant.
On April 17, 2005, the Millstone Nuclear Power Plant in Connecticut was shut down due to a "false alarm" that indicated an unsafe pressure drop in the reactor's steam system when the steam pressure was actually nominal. The false alarm was caused by a tin whisker that short circuited the logic board that was responsible for monitoring the steam pressure lines in the power plant.
Toyota accelerator position sensors false positive.
In September 2011, three NASA investigators claimed that the tin whiskers they identified on the accelerator position sensors of sampled models of Toyota Camry could contribute to the "stuck accelerator" crashes affecting certain Toyota models during 2005–2010. This contradicted an earlier 10-month joint investigation by the National Highway Traffic Safety Administration (NHTSA) and a large group of other NASA researchers that found no electronic defects.
However, in 2012 NHTSA maintained: "We do not believe that tin whiskers are a plausible explanation for these incidents...[the likely cause was] pedal misapplication."
Toyota also maintains that tin whiskers were not the cause of any stuck accelerator issues: "In the words of U.S. Transportation Secretary Ray LaHood, 'The verdict is in. There is no electronic-based cause for unintended high-speed acceleration in Toyotas. Period. According to a Toyota press release, "no data indicates that tin whiskers are more prone to occur in Toyota vehicles than any other vehicle in the marketplace." Toyota also states that "their systems are designed to reduce the risk that tin whiskers will form in the first place."


Qinghai Huading Industrial

Qinghai Huading Industrial Co., Ltd. known as Qinghai Huading or just QHHD, is a holding company established in 1998 and listed on the Shanghai Stock Exchange in 2000. As of 12 June 2015, the company has a market capitalization of 4.682 billion CNY and employs over 4,000 staffs. Through its various subsidiaries, the company is involved mainly in the manufacturing and distribution of machine tools, gearboxes, food machineries, elevator components and LED lightings.
Operations.
The group's core business is the manufacturing of machine tools. As of 2012, Qinghai Huading is the domestic market leader in horizontal machine tools in terms of output volume and has over 90% domestic market share in rail road specific machine tools.
Directors & Officers.
"Officers and Directors data as of Feb 17 2013"


List of integrated circuit packaging types

Integrated circuits are put into protective packages to allow easy handling and assembly onto printed circuit boards and to protect the devices from damage. A very large number of different types of package exist. Some package types have standardized dimensions and tolerances, and are registered with trade industry associations such as JEDEC and Pro Electron. Other types are proprietary designations that may be made by only one or two manufacturers. Integrated circuit packaging is the last assembly process before testing and shipping devices to customers.
Occasionally specially-processed integrated circuit dies are prepared for direct connections to a substrate without an intermediate header or carrier. In flip chip systems the IC is connected by solder bumps to a substrate. In beam-lead technology, the metallized pads that would be used for wire bonding connections in a conventional chip are thickened and extended to allow external connections to the circuit. Assemblies using "bare" chips have additional packaging or filling with epoxy to protect the devices from moisture.
Through-hole packages.
Through-hole technology uses holes drilled through the printed circuit board (PCB) for mounting the components. The component has leads that are soldered to pads on the PCB to electrically and mechanically connect them to the PCB.
Surface mount.
Chip on board is a packaging technique that directly connects a die to a PCB, without an interposer or lead frame.
Chip carrier.
A chip carrier is a rectangular package with contacts on all four edges. Leaded chip carriers have metal leads wrapped around the edge of the package, in the shape of a letter J. Leadless chip carriers have metal pads on the edges. Chip carrier packages may be made of ceramic or plastic and are usually secured to a printed circuit board by soldering, though sockets can be used for testing.
Ball grid array.
Ball grid array (BGA) uses the underside of the package to place pads with balls of solder in grid pattern as connections to PCB.
Package dimensions.
All measurements below are given in mm. To convert mm to mils, divide mm by 0.0254 (i.e., 2.54 mm / 0.0254 = 100 mil).
Multi-chip packages.
A variety of techniques for interconnecting several chips within a single package have been proposed and researched:
By terminal count.
Surface-mount components are usually smaller than their counterparts with leads, and are designed to be handled by machines rather than by humans. The electronics industry has standardized package shapes and sizes (the leading standardisation body is JEDEC).
The codes given in the chart below usually tell the length and width of the components in tenths of millimeters or hundredths of inches. For example, a metric 2520 component is 2.5 mm by 2.0 mm which corresponds roughly to 0.10 inches by 0.08 inches (hence, imperial size is 1008). Exceptions occur for imperial in the two smallest rectangular passive sizes. The metric codes still represent the dimensions in mm, even though the imperial size codes are no longer aligned. Problematically, some manufacturers are developing metric 0201 components with dimensions of , but the imperial 01005 name is already being used for the package. These increasingly small sizes, especially 0201 and 01005, can sometimes be a challenge from a manufacturability or reliability perspective.
Two-terminal packages.
Rectangular passive components.
Mostly resistors and capacitors.
Metal electrode leadless face (MELF).
Mostly resistors and diodes; barrel shaped components, dimensions do not match those of rectangular references for identical codes.
DO-214.
Commonly used for rectifier, Schottky, and other diodes.
Packages with more than six terminals.
Non-packaged devices.
Although surface-mount, these devices require specific process for assembly.
There are often subtle variations in package details from manufacturer to manufacturer, and even though standard designations are used, designers need to confirm dimensions when laying out printed circuit boards.


Robot calibration

Robot calibration is a process used to improve the accuracy of robots, particularly industrial robots which are highly repeatable but not accurate. Robot calibration is the process of identifying certain parameters in the kinematic structure of an industrial robot, such as the relative position of robot links. Depending on the type of errors modeled, the calibration can be classified in three different ways. Level-1 calibration only models differences between actual and reported joint displacement values, (also known as mastering). Level-2 calibration, also known as kinematic calibration, concerns the entire geometric robot calibration which includes angle offsets and joint lengths. Level-3 calibration, also called a non-kinematic calibration, models errors other than geometric defaults such as stiffness, joint compliance, and friction. Often Level-1 and Level-2 calibration are sufficient for most practical needs.
Parametric robot calibration is the process of determining the actual values of kinematic and dynamic parameters of an industrial robot (IR). Kinematic parameters describe the relative position and orientation of links and joints in the robot while the dynamic parameters describe arm and joint masses and internal friction.
Non-parametric robot calibration circumvents the parameter identification. Used with serial robots, it is based on the direct compensation of mapped errors in the workspace. Used with parallel robots, non-parametric calibration can be performed by the transformation of the configuration space.
Robot calibration can remarkably improve the accuracy of robots programmed offline. A calibrated robot has a higher absolute as well as relative positioning accuracy compared to an uncalibrated one; i.e., the real position of the robot end effector corresponds better to the position calculated from the mathematical model of the robot. Absolute positioning accuracy is particularly relevant in connection with robot exchangeability and off-line programming of precision applications. Besides the calibration of the robot, the calibration of its tools and the workpieces it works with (the so-called "cell calibration") can minimize occurring inaccuracies and improve process security.
Accuracy criteria and error sources.
The international standard ISO 9283 sets different performance criteria for industrial robots and suggests test procedures in order to obtain appropriate parameter values. The most important criteria, and also the most commonly used, are pose accuracy (AP) and pose repeatability (RP). Repeatability is particularly important when the robot is moved towards the command positions manually ("Teach-In"). If the robot program is generated by a 3D simulation ("off-line programming"), absolute accuracy is vital, too. Both are generally influenced negatively by kinematic factors. Here especially the joint offsets and deviations in lengths and angles between the individual robot links take effect.
Measurement systems.
There exist different possibilities for pose measurement with industrial robots, e.g. touching reference parts, using supersonic distance sensors, laser interferometry, theodolites, calipers or laser triangulation. Furthermore, there are camera systems which can be attached in the robot's cell or at the IR mounting plate and acquire the pose of a reference object. Measurement and calibration systems are made by such companies as Bluewrist, Dynalog, RoboDK, FARO Technologies, Creaform, Leica, Metris, Metronor, Wiest, Teconsult and Automated Precision.
Mathematical principles.
The robot errors gathered by pose measurements can be minimized by numerical optimization. For kinematic calibration, a complete kinematical model of the geometric structure must be developed, whose parameters can then be calculated by mathematical optimization. The common system behaviour can be described with the vector model function as well as input and output vectors (see figure).
The variables "k, l, m, n" and their derivates describe the dimensions of the single vector spaces. Minimization of the residual error "r" for identification of the optimal parameter vector "p" follows from the difference between both output vectors using the Euclidean norm.
For solving the kinematical optimization problems least-squares descent methods are convenient, e.g. a modified quasi-Newton method. This procedure supplies corrected kinematical parameters for the measured machine, which then, for example, can be used to update the system variables in the controller to adapt the used robot model to the real kinematics.
Results.
The positioning accuracy of industrial robots varies by manufacturer, age, and robot type. Using kinematic calibration, these errors can be reduced to less than a millimeter in most cases. An example of this is shown in the figure to the right.
Accuracy of 6-axis industrial robots can improved by a factor of 10.
Accuracy of parallel robots after calibration can be as low as a tenth of a millimeter.
Sample applications.
In the industry, there is a general trend towards substitution of machine tools and special machines by industrial robots for certain manufacturing tasks whose accuracy demands can be fulfilled by calibrated robots. Through simulation and off-line programming, it is possible to easily accomplish complex programming tasks, such as robot machining. However, contrary to the teach programming method, good accuracy as well as repeatability is required.
In the figure, a current example is shown: In-line measurement in automotive manufacturing, where the common "measurement tunnel" used for 100% inspection with many expensive sensors are partly replaced by industrial robots that carry only one sensor each. This way the total costs of a measurement cell can be reduced significantly. The station can also be re-used after a model change by simple re-programming without mechanical adaptations.
Further examples for precision applications are robot-guided hemming in car body manufacturing, assembly of mobile phones, drilling, riveting and milling in the aerospace industry, and increasingly in medical applications.


SPEED2000

SPEED2000 is a software package designed for electromagnetic simulation for the analysis and design of high-speed electronic systems. It combines an electromagnetic field solver with circuit and transmission line simulations which allows it to compute dynamic electromagnetic interactions within integrated circuits. SPEED2000 provides electrical analysis of integrated circuit (IC) packages and printed circuit boards (PCBs). It is developed and marketed by Sigrity, Inc.
History.
The algorithms on which SPEED2000 is based were initially developed by Dr. Jiayuan Fang (then associate professor of Electrical Engineering at Binghamton University) and his students. The electromagnetic simulation algorithms that he developed were 1000 times faster previous methods.
Dr. Fang patented the algorithms (see below) and founded a company called Sigrity, Inc. to further develop the software. He eventually left Binghamton University to work on his software full-time. The rights to the initial patents are owned by Binghamton University and the royalties provide funding for current research efforts at the university.


Industrial technology

Industrial technology is the use of engineering and manufacturing technology to make production faster, simpler, and more efficient. The industrial technology field employs creative and technically proficient individuals who can help a company achieve efficient and profitable productivity.
Industrial technology programs typically include instruction in optimization theory, human factors, organizational behavior, industrial processes, industrial planning procedures, computer applications, and report and presentation preparation.
Planning and designing manufacturing processes and equipment is the main aspect of being an industrial technologist. An industrial technologist is often responsible for implementing certain designs and processes.
Accreditation and certification.
The USA-based Association of Technology, Management, and Applied Engineering (ATMAE), accredits selected collegiate programs in Industrial Technology in the USA. An instructor or graduate of an Industrial Technology program may choose to become a Certified Technology Manager (CTM) by sitting for a rigorous exam administered by ATMAE covering Production Planning & Control, Safety, Quality, and Management/Supervision.
ATMAE program accreditation is recognized by the Council for Higher Education Accreditation (CHEA) for accrediting Industrial Technology programs. CHEA recognizes ATMAE in the U.S. for accrediting associate, baccalaureate, and master's degree programs in technology, applied technology, engineering technology, and technology-related disciplines delivered by national or regional accredited institutions in the United States.(2011) Industrial technology is also one of the largest industries used.
Knowledge base.
"A career in industrial technology typically entails formal education from an accredited college or university. Opportunities are available to professionals with all levels of education. Those who hold associate degrees typically qualify for the entry-level technician and technologist positions, such as in the maintenance and operation of machinery. Bachelor's degree-holders could fill management and engineering positions, such as plant manager, production supervisor and quality systems engineering technologist. A graduate degree in industrial technology could qualify individuals for jobs in research, teaching and upper-level management".
Industrial Technology includes wide-ranging subject matter and could be viewed as an amalgamation of industrial engineering and business topics with a focus on practicality and management of technical systems with less focus on actual engineering of those systems.
Typical curriculum at a four-year university might include courses on manufacturing process, technology and impact on society, mechanical and electronic systems, quality assurance and control, materials science, packaging, production and operations management, and manufacturing facility planning and design. In addition, the Industrial Technologist may have exposure to more vocational-style education in the form of courses on CNC manufacturing, welding, and other tools-of-the-trade in manufacturing.
Industrial technologist.
Industrial technology program graduates obtain a majority of positions which are applied engineering and/or management oriented. Since "industrial technologist" is not a common job title in the United States, the actual bachelor's degree or associate degree earned by the individual is obscured by the job title he/she receives. Typical job titles for industrial technologists having a bachelor's degree include quality systems engineer, manufacturing engineer, industrial engineer, plant manager, production supervisor, etc. Typical job titles for industrial technologists having a two-year associate degree include project technologist, manufacturing technologist, process technologist, etc.
A technologist curriculum may focus or specialize in a certain technical area of study. Examples of this includes electronics, manufacturing, construction, graphics, automation/robotics, CADD, nanotechnology, aviation, etc.
Technological development in industry.
A major subject of study is technological development in industry. This has been defined as:
Studies in this area often employ a multi-disciplinary research methodology and shade off into the wider analysis of business and economic growth (development, performance). The studies are often based on a mixture of industrial field research and desk-based data analysis and aim to be of interest and use to practitioners in business management and investment (etc.) as well as academics. In engineering, construction, textiles, food and drugs, chemicals and petroleum, and other industries, the focus has been on not only the nature and factors facilitating and hampering the introduction and utilization of new technologies but also the impact of new technologies on the production organization (etc.) of firms and various social and other wider aspects of the technological development process.
How and When Technological development in industry Performed :


Scaif

A scaif is a polishing wheel infused with a mixture of olive oil and diamond dust used in the diamond cutting industry. It was invented in 1456 by Lodewyk van Bercken.
With the scaif, it became possible to polish all the facets of the diamond symmetrically at angles that reflected the light best. This invention revolutionized the diamond cutting industry and correspondingly, much increased the popularity of diamonds.
The scaif consists of a hard disk, parallel to the floor. The disk looks like and is rotated in the same way as a potter's wheel. On the top surface a film of olive oil and diamond dust is placed. Surrounding the disk is a circular frame to catch the oil that is spun off as the disk is rotated.
Hovering just above the surface of the disk is a mechanical arm to hold the diamond. It can be finely adjusted, to move the diamond into the exact position needed for polishing the facets. As the facets are polished more diamond dust is produced, replenishing the supply.


Buckeye Manufacturing Company

The Buckeye Manufacturing Company was a company noted for manufacturing gasoline engines and farm implements. It manufactured the engines for its sister company, the Union Automobile Company.
In time the Lambert founded automobile related subsidiary companies such as the Union Automobile Company, the Lambert Automobile Company, and the Lambert Gas and Gasoline Engine Company. Buckeye Manufacturing Company manufactured the components of the cars assembled by these subsidiaries. The company later produced automobiles and it continued until 1917.
History.
A single Buckeye gasoline buggy automobile was built by the company in 1890, and offered for sale in 1891, though none were produced.


Tex Corp

Tex Corp is an Indian multinational manufacturer of zippers, sliders and other fastening products. Headquartered in Gurgaon, it supplies global fashion retailers primarily in Europe and the United States.
Background.
Formed in New Delhi in 1987 by a group of Indian Institutes of Management alumni, Tex is one of the largest manufacturers and exporters of zipper and fastening products for the apparel industry. It has two manufacturing facilities in India and one each in Bangladesh and Vietnam, becoming the first Indian owned multinational zipper manufacturing organization. Tex's business group also has interests in apparel manufacturing and renewable energy.
Among Tex's clients are the Gap, Macy's, Kohl's, Express, Target, Talbots, Belk, HBC, H&M, Debenhams, Next, Tesco and Matalan. Tex's products are delivered directly to its customers' manufacturing facilities located primarily in the Indian Subcontinent, South-East Asia, Africa and Europe.
Tex adheres to the International Organization for Standardization (ISO)9001:2008 standard. Tex is also an Oeko-Tex Product Class 1 and Eco-tex certified organization. Its products are Consumer Product Safety Improvement Act and Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH) compliant.


Arc welding

Arc welding is a welding process that is used to join metal to metal by using electricity to create enough heat to melt metal, and the melted metals, when cool, result in a binding of the metals. It is a type of welding that uses a welding power supply to create an electric arc between a metal stick ("electrode") and the base material to melt the metals at the point of contact. Arc welding power supplies can deliver either direct (DC) or alternating (AC) current to the work, while consumable or non-consumable electrodes are used.
The welding area is usually protected by some type of shielding gas (e.g. an inert gas), vapor, or slag. Arc welding processes may be manual, semi-automatic, or fully automated. First developed in the late part of the 19th century, arc welding became commercially important in shipbuilding during the Second World War. Today it remains an important process for the fabrication of steel structures and vehicles.
Power supplies.
To supply the electrical energy necessary for arc welding processes, a number of different power supplies can be used. The most common classification is constant current power supplies and constant voltage power supplies. In arc welding, the voltage is directly related to the length of the arc, and the current is related to the amount of heat input. Constant current power supplies are most often used for manual welding processes such as gas tungsten arc welding and shielded metal arc welding, because they maintain a relatively constant current even as the voltage varies. This is important because in manual welding, it can be difficult to hold the electrode perfectly steady, and as a result, the arc length and thus voltage tend to fluctuate. Constant voltage power supplies hold the voltage constant and vary the current, and as a result, are most often used for automated welding processes such as gas metal arc welding, flux cored arc welding, and submerged arc welding. In these processes, arc length is kept constant, since any fluctuation in the distance between the wire and the base material is quickly rectified by a large change in current. For example, if the wire and the base material get too close, the current will rapidly increase, which in turn causes the heat to increase and the tip of the wire to melt, returning it to its original separation distance. Under normal arc length conditions, a constant current power supply with a stick electrode operates at about 20 volts.
The direction of current used in arc welding also plays an important role in welding. Consumable electrode processes such as shielded metal arc welding and gas metal arc welding generally use direct current, but the electrode can be charged either positively or negatively. In general, the positively charged anode will have a greater heat concentration (around 60%). "Note that for stick welding in general, DC+ polarity is most commonly used. It produces a good bead profile with a higher level of penetration. DC- polarity results in less penetration and a higher electrode melt-off rate. It is sometimes used, for example, on thin sheet metal in an attempt to prevent burn-through." "With few exceptions, electrode-positive (reversed polarity) results in deeper penetration. Electrode-negative (straight polarity) results in faster melt-off of the electrode and, therefore, faster deposition rate." Non-consumable electrode processes, such as gas tungsten arc welding, can use either type of direct current (DC), as well as alternating current (AC). With direct current however, because the electrode only creates the arc and does not provide filler material, a positively charged electrode causes shallow welds, while a negatively charged electrode makes deeper welds. Alternating current rapidly moves between these two, resulting in medium-penetration welds. One disadvantage of AC, the fact that the arc must be re-ignited after every zero crossing, has been addressed with the invention of special power units that produce a square wave pattern instead of the normal sine wave, eliminating low-voltage time after the zero crossings and minimizing the effects of the problem.
Duty cycle is a welding equipment specification which defines the number of minutes, within a 10-minute period, during which a given arc welder can safely be used. For example, an 80 A welder with a 60% duty cycle must be "rested" for at least 4 minutes after 6 minutes of continuous welding. Failure to observe duty cycle limitations could damage the welder. Commercial- or professional-grade welders typically have a 100% duty cycle.
Consumable electrode methods.
One of the most common types of arc welding is shielded metal arc welding (SMAW), which is also known as manual metal arc welding (MMAW) or stick welding. An electric current is used to strike an arc between the base material and a consumable electrode rod or "stick". The electrode rod is made of a material that is compatible with the base material being welded and is covered with a flux that gives off vapors that serve as a shielding gas and provide a layer of slag, both of which protect the weld area from atmospheric contamination. The electrode core itself acts as filler material, making a separate filler unnecessary. The process is very versatile, requiring little operator training and inexpensive equipment. However, weld times are rather slow, since the consumable electrodes must be frequently replaced and because slag, the residue from the flux, must be chipped away after welding. Furthermore, the process is generally limited to welding ferrous materials, though specialty electrodes have made possible the welding of cast iron, nickel, aluminum, copper and other metals. The versatility of the method makes it popular in a number of applications including repair work and construction.
Gas metal arc welding (GMAW), commonly called "MIG" (for "metal/inert-gas"), is a semi-automatic or automatic welding process with a continuously fed consumable wire acting as both electrode and filler metal, along with an inert or semi-inert shielding gas flowed around the wire to protect the weld site from contamination. Constant voltage, direct current power source is most commonly used with GMAW, but constant current alternating current are used as well. With continuously fed filler electrodes, GMAW offers relatively high welding speeds; however the more complicated equipment reduces convenience and versatility in comparison to the SMAW process. Originally developed for welding aluminum and other non-ferrous materials in the 1940s, GMAW was soon economically applied to steels. Today, GMAW is commonly used in industries such as the automobile industry for its quality, versatility and speed. Because of the need to maintain a stable shroud of shielding gas around the weld site, it can be problematic to use the GMAW process in areas of high air movement such as outdoors.
Flux-cored arc welding (FCAW) is a variation of the GMAW technique. FCAW wire is actually a fine metal tube filled with powdered flux materials. An externally supplied shielding gas is sometimes used, but often the flux itself is relied upon to generate the necessary protection from the atmosphere. The process is widely used in construction because of its high welding speed and portability.
Submerged arc welding (SAW) is a high-productivity welding process in which the arc is struck beneath a covering layer of granular flux. This increases arc quality, since contaminants in the atmosphere are blocked by the flux. The slag that forms on the weld generally comes off by itself and, combined with the use of a continuous wire feed, the weld deposition rate is high. Working conditions are much improved over other arc welding processes since the flux hides the arc and no smoke is produced. The process is commonly used in industry, especially for large products. As the arc is not visible, it is typically automated. SAW is only possible in the 1F (flat fillet), 2F (horizontal fillet), and 1G (flat groove) positions.
Non-consumable electrode methods.
Gas tungsten arc welding (GTAW), or "tungsten/inert-gas" (TIG) welding, is a manual welding process that uses a non-consumable electrode made of tungsten, an inert or semi-inert gas mixture, and a separate filler material. Especially useful for welding thin materials, this method is characterized by a stable arc and high quality welds, but it requires significant operator skill and can only be accomplished at relatively low speeds. It can be used on nearly all weldable metals, though it is most often applied to stainless steel and light metals. It is often used when quality welds are extremely important, such as in bicycle, aircraft and marine applications.
A related process, plasma arc welding, also uses a tungsten electrode but uses plasma gas to make the arc. The arc is more concentrated than the GTAW arc, making transverse control more critical and thus generally restricting the technique to a mechanized process. Because of its stable current, the method can be used on a wider range of material thicknesses than can the GTAW process and is much faster. It can be applied to all of the same materials as GTAW except magnesium; automated welding of stainless steel is one important application of the process. A variation of the process is plasma cutting, an efficient steel cutting process.
Other arc welding processes include atomic hydrogen welding, carbon arc welding, electroslag welding, electrogas welding, and stud arc welding.
Corrosion issues.
Some materials, notably high-strength steels, aluminum, and titanium alloys, are susceptible to hydrogen embrittlement. If the electrodes used for welding contain traces of moisture, the water decomposes in the heat of the arc and the liberated hydrogen enters the lattice of the material, causing its brittleness. Stick electrodes for such materials, with special low-hydrogen coating, are delivered in sealed moisture-proof packaging. New electrodes can be used straight from the can, but when moisture absorption may be suspected, they have to be dried by baking (usually at ) in a drying oven. Flux used has to be kept dry as well.
Some austenitic stainless steels and nickel-based alloys are prone to intergranular corrosion. When subjected to temperatures around for too long a time, chromium reacts with carbon in the material, forming chromium carbide and depleting the crystal edges of chromium, impairing their corrosion resistance in a process called sensitization. Such sensitized steel undergoes corrosion in the areas near the welds where the temperature-time was favorable for forming the carbide. This kind of corrosion is often termed weld decay.
Knifeline attack (KLA) is another kind of corrosion affecting welds, impacting steels stabilized by niobium. Niobium and niobium carbide dissolves in steel at very high temperatures. At some cooling regimes, niobium carbide does not precipitate, and the steel then behaves like unstabilized steel, forming chromium carbide instead. This affects only a thin zone several millimeters wide in the very vicinity of the weld, making it difficult to spot and increasing the corrosion speed. Structures made of such steels have to be heated in a whole to about , when the chromium carbide dissolves and niobium carbide forms. The cooling rate after this treatment is not important.
Filler metal (electrode material) improperly chosen for the environmental conditions can make them corrosion-sensitive as well. There are also issues of galvanic corrosion if the electrode composition is sufficiently dissimilar to the materials welded, or the materials are dissimilar themselves. Even between different grades of nickel-based stainless steels, corrosion of welded joints can be severe, despite that they rarely undergo galvanic corrosion when mechanically joined.
Safety issues.
Welding can be a dangerous and unhealthy practice without the proper precautions; however, with the use of new technology and proper protection the risks of injury or death associated with welding can be greatly reduced.
Heat, fire, and explosion hazard.
Because many common welding procedures involve an open electric arc or flame, the risk of burns from heat and sparks is significant. To prevent them, welders wear protective clothing in the form of heavy leather gloves and protective long sleeve jackets to avoid exposure to extreme heat, flames, and sparks. The use of compressed gases and flames in many welding processes also pose an explosion and fire risk; some common precautions include limiting the amount of oxygen in the air and keeping combustible materials away from the workplace.
Eye damage.
Exposure to the brightness of the weld area leads to a condition called arc eye in which ultraviolet light causes inflammation of the cornea and can burn the retinas of the eyes. Welding goggles and helmets with dark face plates—much darker than those in sunglasses or oxy-fuel goggles—are worn to prevent this exposure. In recent years, new helmet models have been produced featuring a face plate which automatically self-darkens electronically. To protect bystanders, transparent welding curtains often surround the welding area. These curtains, made of a polyvinyl chloride plastic film, shield nearby workers from exposure to the UV light from the electric arc.
Inhaled matter.
Welders are also often exposed to dangerous gases and particulate matter. Processes like flux-cored arc welding and shielded metal arc welding produce smoke containing particles of various types of oxides. The size of the particles in question tends to influence the toxicity of the fumes, with smaller particles presenting a greater danger. Additionally, many processes produce various gases (most commonly carbon dioxide and ozone, but others as well) that can prove dangerous if ventilation is inadequate.
Electrical safety.
While the open-circuit voltage of an arc welding machine may be only a few tens of volts up to about 120 volts, even these low voltages can present a hazard of electric shock for the operators. Locations such as ship's hulls, storage tanks, metal structural steel, or in wet areas are usually at earth ground potential and operators may be standing or resting on these surfaces during operating of the electric arc. Welding machines operating off AC power distribution systems must isolate the arc circuit from earth ground to prevent insulation faults in the machine from exposing operators to high voltage. The return clamp of the welding machine is located near to the work area, to reduce the risk of stray current traveling a long way to create heating hazards or electric shock exposure, or to cause damage to sensitive electronic devices. Welding operators are careful to install return clamps so that welding current cannot pass through the bearings of electric motors, conveyor rollers, or other rotating components, which would cause damage to bearings. Welding on electrical buswork connected to transformers presents a danger of the low welding voltage being "stepped up" to much higher voltages, so extra grounding cables may be required.
Interference with pacemakers.
Certain welding machines which use a high frequency alternating current component have been found to affect pacemaker operation when within 2 meters of the power unit and 1 meter of the weld site.
History.
While examples of forge welding go back to the Bronze Age and the Iron Age, arc welding did not come into practice until much later.
In 1800 Humphry Davy discovered the short pulsed electric arcs. Independently, a Russian physicist named Vasily Petrov discovered the continuous electric arc in 1802 and subsequently proposed its possible practical applications, including welding. Arc welding was first developed when Nikolai Benardos presented arc welding of metals using a carbon electrode at the International Exposition of Electricity, Paris in 1881, which was patented together with Stanisław Olszewski in 1887. In the same year, French electrical inventor Auguste de Méritens also invented a carbon arc welding method, patented in 1881, which was successfully used for welding lead in the manufacture of lead–acid batteries. The advances in arc welding continued with the invention of metal electrodes in the late 19th century by a Russian, Nikolai Slavyanov (1888), and an American, C. L. Coffin. Around 1900, A. P. Strohmenger released in Britain a coated metal electrode which gave a more stable arc. In 1905 Russian scientist Vladimir Mitkevich proposed the usage of three-phase electric arc for welding. In 1919, alternating current welding was invented by C. J. Holslag but did not become popular for another decade.
Competing welding processes such as resistance welding and oxyfuel welding were developed during this time as well; but both, especially the latter, faced stiff competition from arc welding especially after metal coverings (known as flux) for the electrode, to stabilize the arc and shield the base material from impurities, continued to be developed.
During World War I welding started to be used in shipbuilding in Great Britain in place of riveted steel plates. The Americans also became more accepting of the new technology when the process allowed them to repair their ships quickly after a German attack in the New York Harbor at the beginning of the war. Arc welding was first applied to aircraft during the war as well, and some German airplane fuselages were constructed using this process. In 1919, the British shipbuilder Cammell Laird started construction of a merchant ship, the "Fullagar", with an entirely welded hull; she was launched in 1921.
During the 1920s, major advances were made in welding technology, including the 1920 introduction of automatic welding in which electrode wire was continuously fed. Shielding gas became a subject receiving much attention as scientists attempted to protect welds from the effects of oxygen and nitrogen in the atmosphere. Porosity and brittleness were the primary problems and the solutions that developed included the use of hydrogen, argon, and helium as welding atmospheres. During the following decade, further advances allowed for the welding of reactive metals such as aluminum and magnesium. This, in conjunction with developments in automatic welding, alternating current, and fluxes fed a major expansion of arc welding during the 1930s and then during World War II.
During the middle of the century, many new welding methods were invented. Submerged arc welding was invented in 1930 and continues to be popular today. In 1932 a Russian, Konstantin Khrenov successfully implemented the first underwater electric arc welding. Gas tungsten arc welding, after decades of development, was finally perfected in 1941 and gas metal arc welding followed in 1948, allowing for fast welding of non-ferrous materials but requiring expensive shielding gases. Using a consumable electrode and a carbon dioxide atmosphere as a shielding gas, it quickly became the most popular metal arc welding process. In 1957, the flux-cored arc welding process debuted in which the self-shielded wire electrode could be used with automatic equipment, resulting in greatly increased welding speeds. In that same year, plasma arc welding was invented. Electroslag welding was released in 1958 and was followed by its cousin, electrogas welding, in 1961.


Product strategy

Product strategy defines the high-level plan for developing and marketing a product, how the product supports the business strategy and goals, and is brought to life through product roadmaps. A product strategy describes a vision of the future with this product, the ideal customer profile and market to serve, go-to-market and positioning (marketing), thematic areas of investment, and measures of success. A product strategy sets the direction for new product development. Companies utilize the product strategy in strategic planning and marketing to set the direction of the company's activities. The product strategy is composed of a variety of sequential processes in order for the vision to be effectively achieved. The strategy must be clear in terms of the target customer and market of the product in order to plan the roadmap needed to achieve strategic goals and give customers better value.
Goals of product strategy.
Product strategy aims to provide context for what the product and business intends to achieve, the target customers and market, and the work to accomplish.
Vision provides the big picture of what the company is trying to achieve. Without vision, it will be difficult for stakeholders to understand its direction and it will lack connection to a broader picture.
Execution is defined by the product roadmap. While the product strategy outlines the elements of the product and the company's target market, the product roadmap explains how the vision will be executed
Big picture context provides the background of each feature and how it relates to larger goals. It also include details in which certain features will be built, and in what order.
Initiatives are the high-level efforts that help achieve goals. For example, performance improvements and expansion of markets.
Example.
Product differentiation occurs when companies have to distinguish a certain product in the marketplace when competing for a product that bring about the same need (e.g. tea) amongst different firms. In order to do so, the aim is to make the product more attractive to the marketplace compared to other competitors. This does not only include price, but also features of the product, quality, packaging, benefits and services. Successful product differentiation creates a comparative advantage for the firm.
As an example, a companies competitor in the market sells Tea A but they sell Tea B, so the company will then have to focus on producing Tea B so that consumers find their product to be more appealing (in terms of price, taste and services) compared to their competitors.
Product Life Cycle Concept.
The product life cycle concept consist of 4 stages: introduction, growth, maturity, obsolescence. It outlines the stages the product was first introduced into the market until it is finally removed from the market. The length of the life cycle, duration of each stage and the shape of the curve vary widely for different products. Not all products reach the final stage and some may continue to rise or even fall.
Obsolescence.
To extend a life of the product, techniques include advertising, price reduction (attract new customers), adding value to the product (new features), explore new markets (selling the product overseas) and new packaging (freshen up old packaging).
Product Platform Strategy.
Beyond individual-product strategy is platform strategy, where the focus is on multiple products. There are two very different types of platforms: digital platforms in technology, and physical platforms in other fields.
A digital platform is an ecosystem designed to enable different groups to co-create value through “plug-and-play” capabilities. The technology infrastructure of the platform touches customers and developers beyond the firm's boundaries. LinkedIn, Facebook, Google and Amazon—in fact most technology businesses—have platform-based business models.
Physical platforms in other industries refer to product family or product portfolio platforms intended to reduce manufacturing and development costs for new products. In this case a platform is a common architecture, collection of assets, component designs, subsystems, or other elements shared by several products. Given that the components and subsystems have already been debugged and tested, the resulting products should have higher quality. Since platform development occurs less frequently than product development, major platform decisions do not need to be made as often. This has the potential to foster lean product development. However, there are downsides: high upfront costs, risk of platform obsolescence, risk of platform recall affecting numerous products, and potential duplication of effort.


Machine factory

A machine factory is a company, that produces machines. These companies traditionally belong to the heavy industry sector in comparison to a more consumer oriented and less capital intensive light industry. Today many companies make more sophisticated smaller machines, and they belong to the light industry. The economic sector of machine factories is called the machine industry.
History.
The machinery factories came into existence in the course of the Industrial Revolution. Late 18th century most production machines, were still made of wood and manufactured in local workshops. The first industrial factories, such as cotton mills and cotton weavers, started their own workshops, where clockmakers, instrument makers, joiners and cabinet makers were employed to build and maintain the production machines.
In the first half of the 19th century gradually the wooden machinery got replaced by metal machine. The machine building gradually broke loose from the textile industry and independent companies emerged specializing in textile machinery, machine tools, locomotives, large steam engines, etc. Most companies in countries as England, France and Germany kept making their own special tools and machines. Lintsen recalled that "only shortly before 1850, there is clear evidence of success in the effort to build 'machines with machines'. A number of so-called machine tools - lathes, planers, drills, cutters - gained the degree of accuracy needed to produce larger series of interchangeable parts. But even these standardization of parts did not mean the end of the individual craftsmanship in the machine industry."
The first machine tools offered for sale (i.e., commercially available) were constructed by Matthew Murray in England around 1800. Others, such as Henry Maudslay, James Nasmyth, and Joseph Whitworth, soon followed the path of expanding their entrepreneurship from manufactured end products and millwright work into the realm of building machine tools for sale. in the 1830s James Nasmyth had "somewhat to his surprise... discovered, that there was really a market emerging for readymade lathes, planers, drills and flat banks. That demand partly originated from the people building the Lancashire textile machinery, and partly from the new phenomenon: the railways. The fast-growing rail network had locomotives, equipped repair shops, tracks and more demands."
In the second part of the 19th century more and more machine factories were started. These companies partly grew out of iron foundries, shipyards, forges and repair shops. Many production machines were sold to machine shops, where parts and consumer products were produced. Early 20th century several motorcycle and automobile manufacturers began their own machine factories.
Nowadays, many of the contemporary machine factories are smaller in size and belong to the light or medium metal. This type of companies generally produce specific production machines and /or devices, in which fine mechanics and electronics often plays a significantly role. Some of these types of companies have been around for decades, others are constantly created.
Types of machine factories.
Agricultural machine factories.
Agricultural machinery is machinery used in the operation of an agricultural area or farm. There is a range of machinery from tractor and to agricultural implements for soil cultivation, planting, fertilizing & pest control, irrigation, produce sorter, harvesting, hay making, loading and milking. These are produced by agricultural machinery manufacturers, and farming machines factories.
Engine manufacturers.
An engine or motor is a machine designed to convert energy into useful mechanical motion. Heat engines, including internal combustion engines and external combustion engines (such as steam engines) burn a fuel to create heat, which then creates motion. Electric motors convert electrical energy into mechanical motion, pneumatic motors use compressed air and others—such as clockwork motors in wind-up toys—use elastic energy. In biological systems, molecular motors, like myosins in muscles, use chemical energy to create motion.
Home appliance manufacturers.
Home appliances are electrical/mechanical machines which accomplish some household functions, such as cooking or cleaning.
This division is noticeable in the maintenance and repair of these kinds of products. Brown goods usually require high technical knowledge and skills (which get more complex with time, such as going from a soldering iron to a hot-air soldering station), while white goods may need more practical skills and "brute force" to manipulate the devices and heavy tools required to repair them.
Specific machine factories in this field are sewing machine factory, and washing machine factory.
Industrial machine manufacturers.
Industrial machine manufacturers produce machine tools, production machines and other industrial equipment.
Machine tool industry.
A machine tool builder in the broadest sense is a corporation or person that builds machine tools. In the most common (and economically significant) sense of the term, a machine tool builder is a corporation whose business is building machine tools for sale to manufacturers, who use them to manufacture products. The machine tools often make interchangeable parts, which are assembled into subassemblies or finished assemblies, ending up sold to consumers, either directly or through other businesses at intermediate links of a value-adding chain. Alternatively, the machine tools may help make molds or dies, which then make the parts for the assemblies.


Digital embossing

Digital embossing is a digital printing technology enhancement process. Digital embossing eliminates the need for printing plates, molds, chemicals, and solvents. The process emits no pollutants or waste and reduces energy use. The high resolution inkjet technology enables selective coating with variable thickness and stamp-less embossing. Digital embossing allows for on-demand printing of as few as one item in thousands of copies.
Digital embossing was invented by Scodix, an Israel-based startup company that produces equipment for print enhancement applications in the commercial and packaging industries. Digital embossing enhancement technology was first unveiled at IPEX 2010 on the Scodix1200™ UV DigitalEmbossing™ press.
Digital embossing can be specified by different print modes.
Preparation.
The preparation for digital embossing requires an additional black separation from the image. The accuracy of the process (each sheet is registered optically before printing) enables embossing of complex shapes.
Production time.
Digital embossing typically adds two minutes to printing production time.


The 2016 Copa Sudamericana elimination stages were played from 9 August to 15 September 2016. A total of 46 teams competed in the elimination stages to decide 15 of the 16 places in the final stages of the 2016 Copa Sudamericana.
Draw.

The draw of the tournament was held on 12 July 2016, 20:00 CLT , at the Espacio Riesco Convention and Events Center in Huechuraba, Chile.
For the first stage, the 32 teams were divided into two zones:
Teams which qualified for berths 1 were drawn against teams which qualified for berths 4, and teams which qualified for berths 2 were drawn against teams which qualified for berths 3, with the former hosting the second leg in both cases. Teams from the same association could not be drawn into the same tie.
For the second stage, the 30 teams, including the 16 winners of the first stage (eight from South Zone, eight from North Zone), whose identity was not known at the time of the draw, and the 14 teams which entered the second stage, were divided into three sections:
Format.

In the elimination stages (first stage and second stage), each tie was played on a home-and-away two-legged basis. If tied on aggregate, the away goals rule would be used. If still tied, extra time would not be played, and the penalty shoot-out would be used to determine the winner (Regulations Article 5.1). The 15 winners of the second stage (eight from winners of the first stage, four from Brazil, three from Argentina) advanced to the round of 16 to join the defending champions (Santa Fe).
First stage.
The first legs were played on 9–11 August, and the second legs were played on 16–18 August 2016.

!colspan=6|South Zone
!colspan=6|North Zone
Match G1.
"Cerro Porteño won 2–1 on aggregate and advanced to the second stage (Match O8)."
Match G2.
"Tied 1–1 on aggregate, Sportivo Luqueño won on away goals and advanced to the second stage (Match O16)."
Match G3.
"Bolívar won 3–2 on aggregate and advanced to the second stage (Match O4)."
Match G4.
"Real Potosí won 4–2 on aggregate and advanced to the second stage (Match O8)."
Match G5.
"Tied 1–1 on aggregate, Blooming won on penalties and advanced to the second stage (Match O6)."
Match G6.
"Tied 2–2 on aggregate, Sol de América won on penalties and advanced to the second stage (Match O13)."
Match G7.
"Tied 0–0 on aggregate, Montevideo Wanderers won on penalties and advanced to the second stage (Match O11)."
Match G8.
"Palestino won 4–0 on aggregate and advanced to the second stage (Match O10)."
Match G9.
"Emelec won 6–1 on aggregate and advanced to the second stage (Match O2)."
Match G10.
"Tied 2–2 on aggregate, Real Garcilaso won on away goals and advanced to the second stage (Match O10)."
Match G11.
"Junior won 5–2 on aggregate and advanced to the second stage (Match O6)."
Match G12.
"Deportivo La Guaira won 1–0 on aggregate and advanced to the second stage (Match O2)."
Match G13.
"Tied 2–2 on aggregate, Zamora won on penalties and advanced to the second stage (Match O11)."
Match G14.
"Independiente Medellín won 2–1 on aggregate and advanced to the second stage (Match O16)."
Match G15.
"Tied 2–2 on aggregate, Sport Huancayo won on away goals and advanced to the second stage (Match O13)."
Match G16.
"Atlético Nacional won 6–0 on aggregate and advanced to the second stage (Match O4)."
Second stage.
The first legs were played on 23–25 August, and the second legs were played on 31 August and 13–15 September 2016.

Match O1.
"Santa Cruz won 1–0 on aggregate and advanced to the round of 16 (Match A)."
Match O2.
"Deportivo La Guaira won 4–2 on aggregate and advanced to the round of 16 (Match B)."
Match O3.
"Chapecoense won 3–2 on aggregate and advanced to the round of 16 (Match C)."
Match O4.
"Atlético Nacional won 2–1 on aggregate and advanced to the round of 16 (Match D)."
Match O5.
"Belgrano won 2–1 on aggregate and advanced to the round of 16 (Match E)."
Match O6.
"Junior won 3–1 on aggregate and advanced to the round of 16 (Match F)."
Match O7.
"Tied 5–5 on aggregate, Flamengo won on away goals and advanced to the round of 16 (Match G)."
Match O8.
"Cerro Porteño won 7–0 on aggregate and advanced to the round of 16 (Match H)."
Match O10.
"Palestino won 3–2 on aggregate and advanced to the round of 16 (Match G)."
Match O11.
"Montevideo Wanderers won 2–0 on aggregate and advanced to the round of 16 (Match F)."
Match O12.
"Tied 2–2 on aggregate, Coritiba won on away goals and advanced to the round of 16 (Match E)."
Match O13.
"Sol de América won 2–1 on aggregate and advanced to the round of 16 (Match D)."
Match O14.
"Independiente won 3–0 on aggregate and advanced to the round of 16 (Match C)."
Match O15.
"San Lorenzo won 4–3 on aggregate and advanced to the round of 16 (Match B)."
Match O16.
"Independiente Medellín won 3–2 on aggregate and advanced to the round of 16 (Match A)."


Steel casting

Steel casting is a specialized form of casting involving various types of steel cast to either final/net or near-net shape. Steel castings are used when iron castings cannot deliver enough strength or shock resistance.
Examples of items that are steel castings include: hydroelectric turbine wheels, forging presses, gears, railroad truck frames, valve bodies, pump casings, mining machinery, marine equipment, turbocharger turbines and engine cylinder blocks.
Steel castings are categorized into two general groups: carbon steels and alloy steels.
Steel castability.
Steel is more difficult to cast than iron. It has a higher melting point and greater shrinkage rate, which requires consideration during mold design. Risers should be given more capacity to draw from as the metal cools and shrinks. Attention should be paid to the thickness of mold cavities, as thinner areas will cool quicker than thicker areas, which can create internal stress points that can lead to fracture.
Molten steel is also less fluid than molten iron, making it more difficult to pour and fill intricate gaps in a mold cavity. Molten steel is also more likely to react with internal mold surfaces, making for more unpredictable results.
Machinability.
Cast parts often require machining to achieve accurate tolerances and desired surface finishes. Carbon steel is the easiest type of steel to machine. High-carbon steel can be more time consuming to cut or grind, and will wear tools faster. Low-carbon steel can get gummy, making it difficult to work with.
Generally, the presence of alloys used to increase mechanical performance often make machining more difficult.
Damping ability.
Casting is often a valuable means to creating intricate parts used in machine applications where vibration is often a factor. Cast steel typically has a lower damping ability than cast iron, which can lead to excess vibration and noise in the form of ringing or squealing.
Impact and wear resistance.
Most steels offer a good balance of strength and ductility, which makes them extremely tough. This allows them to withstand significant stress and strain without fracturing. Steel can also be fairly wear-resistant. Alloy additions can increase both impact and wear resistance.
Steel casting alloys.
Alloy steel castings are broken down into two categories: low-alloy steels and high-alloy steels. Low-alloy steels contain less than 8% alloying content and high-alloy steels have 8% or more.
This is a table of some steel casting alloys:
Terminology.
In present-day vocabulary, the term "cast steel" is almost always used in its sense referring to steel castings. Between the late 19th and mid 20th centuries, this was not always true, which is worth understanding if one is reading historical documents; see "cast steel" for details.


Ticket punch

A ticket punch (or control nippers) is a hand tool for permanently marking admission tickets and similar items of paper or card stock. It makes a perforation and a corresponding chad. A ticket punch resembles a hole punch, differing in that the ticket punch has a longer jaw (or "reach") and the option of having a distinctive die shape. A ticket punch resembles a needle punch in that it makes a distinctive pattern in the item punched, but differs in that it makes a chad.
Uses.
Ticket punches are widely used to mark railway passenger tickets, particularly if it is important when and where the ticket was punched. Ticket punches were also widely used in orienteering but have been replaced by needle punches (see control point in Orienteering).
Ticket punches also have decorative uses, involving both their perforations and their chads. Available die shapes include many geometric shapes, silhouettes of objects or animals. Die shapes for company logos and other proprietary images can be manufactured by special arrangement. These are used to punch decorative holes in the margins of pieces of paper, and to make small confetti.
Punched tickets were issued in BEST buses in Mumbai till 2011, when they were replaced with electronic ticketing systems. The older tickets have been reportedly used in artwork as well as in games.


Thermographic printing

Thermographic printing refers to two types of printing, both of which rely on heat to create the letters or images on a sheet of paper.
The simplest type of thermography is where the paper has been coated with a material that changes colour on heating. This is called thermal printing and was used in older model fax machines and is used in most shop till receipt printers. This is called direct thermal.
More complex is thermal transfer printing that melts print off a ribbon and onto the sheet of paper.
Thermography as raised print process.
Thermography is also the name of a post print process that is achieved today using traditional printing methods coupled with thermography machines. Thermography machines consist of three sections with a through conveyor.
The first section applies thermographic/embossing powder, made from plastic resins, to the substrate (normally paper). The areas selected for raised printing are printed with slow-drying inks that do not contain dryers or hardeners so that they remain wet during the application of powder. This ink is dried and hardened later during the heating process.
The second section of the process is a vacuum system that removes excess powder from areas of the sheet that were not printed.
The third section of the process conveys the product through a radiant oven where it is exposed to temperatures of 900 to 1300ºF (500-700ºC). The heating process takes on the order of 2.5 to 3 seconds. The substrate (usually paper) has a peak in IR absorption at the wavelength used. Through conduction from the paper, the powder temperature rapidly increases and starts melting. When the process is correctly adjusted, the center of the largest filmed areas reach sufficient quality level as the product exits the heater. The melted ink then solidifies as the product cools.
This process is sometimes produced using manual powdering. The substrate with the wet ink is dipped into the powdered polymer. The sheet is then tilted back and forth, rolling the powder across the image. The excess powder is then removed by raising the substrate to a vertical position and lightly tapping the back side. The powdered sheet is then fed into a radiant heating system (as above) at a speed that achieves a good-quality melted film. In the case of craft applications, the powder is melted using a heatgun that blows hot air.
It is commonly used on wedding invitations, letterheads, business cards, greeting cards, gift wrap, packaging, etc. It is sometimes used in diploma printing as a low-cost alternative to engraved embossing.


Linear stage

A linear stage or translation stage is a component of a precise motion system used to restrict an object to a single axis of motion. The term linear slide is often used interchangeably with "linear stage", though technically "linear slide" refers to a linear motion bearing, which is only a component of a linear stage. All linear stages consist of a platform and a base, joined by some form of guide or linear bearing in such a way that the platform is restricted to linear motion with respect to the base. In common usage, the term linear stage may or may not also include the mechanism by which the position of the platform is controlled relative to the base.
Principle of operation.
In three-dimensional space, an object may either rotate about, or translate along any of three axes. Thus the object is said to have six degrees of freedom (3 rotational and 3 translational). A linear stage exhibits only one degree of freedom (translation along one axis). In other words, linear stages operate by physically restricting 3 axes of rotation and 2 axes of translation thus allowing for motion on only one translational axis.
Guide types.
Linear stages consist of a platform that moves relative to a base. The platform and base are joined by some form of guide which restricts motion of the platform to only one dimension. A variety of different styles of guides are used, each with benefits and drawbacks making each guide type more appropriate for some applications than for others.
Position control methods.
The position of the moving platform relative to the fixed base is typically controlled by a linear actuator of some form, whether manual, motorized, or hydraulic/pneumatic. The most common method is to incorporate a lead screw passing through a lead nut in the platform. The rotation of such a lead screw may be controlled either manually or by a motor.
Manual.
In manual linear stages, a control knob attached to a lead screw is typically used. The knob may be indexed to indicate its angular position. The linear displacement of the stage is related to the angular displacement of the knob by the lead screw pitch. For example if the lead screw pitch is 0.5 mm then one full revolution of the knob will move the stage platform 0.5 mm relative to the stage base. If the knob has 50 index marks around its circumference, then each index division is equivalent to 0.01 mm of linear motion of the stage platform.
Precision stages such as those used for optics do not use a lead screw, but instead use a fine-pitch screw or a micrometer which presses on a hardened metal pad on the stage platform. Rotating the screw or micrometer pushes the platform forward. A spring provides restoring force to keep the platform in contact with the actuator. This provides more precise motion of the stage. Stages designed to be mounted vertically use a slightly different arrangement, where the actuator is attached to the movable platform and its tip rests on a metal pad on the fixed base. This allows the weight of the platform and its load to be supported by the actuator rather than the spring.
Stepper motor.
In some automated stages a stepper motor may be used in place of, or in addition to a manual knob. A stepper motor moves in fixed increments called steps. In this sense it behaves very much like an indexed knob. If the lead screw pitch is 0.5 mm and the stepper motor has 200 steps per revolution (as is common), then each revolution of the motor will result in 0.5 mm of linear motion of the stage platform, and each step will result in 0.0025 mm of linear motion.
DC motor with encoder.
In other automated stages a DC motor may be used in place of a manual control knob. A DC motor does not move in fixed increments. Therefore an alternate means is required to determine stage position. A scale may be attached to the internals of the stage and an encoder used to measure the position of the stage relative to the scale and report this to the motor controller, allowing a motion controller to reliably and repeatably move the stage to set positions.
Multiple axis stage configurations.
For position control in more than one direction, multiple linear stages may be used together. A "two-axis" or "X-Y" stage can be assembled from two linear stages, one mounted to the platform of the other such that the axis of motion of the second stage is perpendicular to that of the first. A two-axis stage with which many people are familiar is a microscope stage, used to position a slide under a lens. A "three-axis" or "X-Y-Z" stage is composed of three linear stages mounted to each other (often with the use of an additional angle bracket) such that the axes of motion of all stages are orthogonal. Some two-axis and three-axis stages are integrated designs rather than being assembled from separate single-axis stages. Some multiple-axis stages also include rotary or tilt elements such as rotary stages or positioning goniometers. By combining linear and rotary elements in various ways, four-axis, five-axis, and six-axis stages are also possible. Linear stages take an advanced form of high performance positioning systems in applications which require a combination of high speed, high precision and high force.
Application.
Semiconductor manufacturing.
Linear stages are used in semiconductor devices fabrication process for precise linear positioning of wafers of the purposes of wafer mapping dielectric, characterization, and epitaxial layer monitoring where positioning speed and precision are critical.


Rotary stage

A rotary stage is a component of a motion system used to restrict an object to a single axis of rotation. The terms rotary table or rotation stage are often used interchangeably with rotary stage. All rotary stages consist of a platform and a base, joined by some form of guide in such a way that the platform is restricted to rotation about a single axis with respect to the base. In common usage, the term rotary stage may or may not also include the mechanism by which the angular position of the platform is controlled relative to the base.
Principle of operation.
In three-dimensional space, an object may either rotate about, or translate along, any of three axes. Thus, the object is said to have six degrees of freedom (3 rotational and 3 translational). A rotary stage exhibits only one degree of freedom (rotation about one axis). In other words, rotary stages operate by physically restricting 3 axes of translation and 2 axes of rotation.
Bearing types.
Rotary stages consist of a platform that moves relative to a base. The platform and base are joined by some form of bearing which restricts motion of the platform to rotation about a single axis. A variety of different styles of bearings are used, each with benefits and drawbacks, making them more appropriate for some applications than for others.
Plain bearing.
A plain bearing is simply two surfaces sliding against each other. Typically, a circular step on the platform mates snugly with a circular depression in the base allowing free rotation while minimizing side to side motion. A rotary stage built with this type of bearing is usually only used for coarse positioning and is adjusted manually simply by turning the platform. Index marks on either the base or the platform are often provided, allowing for somewhat repeatable positioning of the platform relative to the base.
Rolling-element bearing.
This type of rotary stage includes ball bearing stages, crossed roller bearing stages, and possibly others. Any of a number of different rolling-element bearings may be employed. Typically, a pair of bearings is used and they are preloaded to take up any slack which could result in the stage platform lifting relative to the base.
Position control methods.
Manual direct.
Some rotary stages are operated simply by turning the platform by hand. The platform may have index marks for setting different angular positions relative to the base. A locking mechanism may be provided to fix the platform to the base at the desired position.
Manual worm drive.
For more precise position control, a worm drive may be used. A worm wheel is fixed to the rotating platform and meshes with a worm in the base. Rotation of the worm via a manual control knob causes the platform to rotate with respect to the base. Index marks on both the control knob and the platform can be used to locate the platform very precisely and repeatably with respect to the base.
Stepper motor with worm drive.
Replacing the manual control knob in the above manual worm drive scenario a stepper motor allows positioning of the rotary stage to be automated. A stepper motor rotates in fixed increments or steps. The number of steps moved is controlled by the stepper motor controller. In this sense, the stepper motor behaves much like an indexed control knob.
DC motor and encoder with worm drive.
A DC motor may also be used in place of a manual control knob. A DC motor does not move in fixed increments. Therefore, an alternate means is required to determine stage position. An encoder may be attached to the DC motor and used to report the angular position of the motor to the motor controller, allowing a motion controller to reliably and repeatably move the stage to set positions.
Linear actuator.
When precise angular positioning over only a small total angle is required, a linear actuator (either manual, or motorized) may be used. Typically, the range of motion possible is only 10° to 20° of rotation. The linear actuator presses against a contact surface fixed to the stage platform such that extension or retraction of the actuator causes the platform to rotate. The stage platform is sprung against the actuator tip so that the contact surface stays in contact with the actuator tip when the actuator retracts.


Molding (process)

Molding (American English) or moulding (British and Commonwealth English; see spelling differences) is the process of manufacturing by shaping liquid or pliable raw material using a rigid frame called a mold or matrix. This itself may have been made using a pattern or model of the final object.
A mold or mould is a hollowed-out block that is filled with a liquid or pliable material such as plastic, glass, metal, or ceramic raw material. The liquid hardens or sets inside the mold, adopting its shape. A mold is a counterpart to a cast. The very common bi-valve molding process uses two molds, one for each half of the object.
Articulated molds have multiple pieces that come together to form the complete mold, and then disassemble to release the finished casting; they are expensive, but necessary when the casting shape has complex overhangs.
Piece-molding uses a number of different molds, each creating a section of a complicated object. This is generally only used for larger and more valuable objects.
Blow molding is a manufacturing process for forming and joining hollow plastic or glass parts.
A manufacturer who makes molds is called a moldmaker. A release agent is typically used to make removal of the hardened/set substance from the mold more easily effected. Typical uses for molded plastics include molded furniture, molded household goods, molded cases, and structural materials.
Types.
There are several types of molding methods.
These includes: