Reishauer

Reishauer is a Swiss machine tool builder based in Wallisellen, which manufactures gear grinding machines.
The company was founded in 1788 by the toolmaker Hans Jakob Däniker as a craft enterprise in Zurich. In 1870, the company was officially registered as a tool factory. In 1945, the first continuous generating gear grinding machine, ZA, was launched on the market, introducing a form of gear grinding that is today known as the Reishauer process. Soon after this, production expanded to gear parts outside machine-tool-engineering and met the requirements of the aircraft industry and the automotive industry. Reishauer AG is a subsidiary of Reishauer Beteiligungen AG, to which the German Felsomat AG has been a part of since 2010. The most important customers are the automotive industry and its suppliers.
Reishauer manufactures: gear grinding machines, grinding and dressing tools, clamping systems, and automation solutions. All components are supplied from one source with more than 80% vertical integration. Reishauer describes its performance system as a Circle of Competence, in which all machine components, tooling, and automation are manufactured in-house.
History.
Foundation as a toolmaker (from 1788).
The company was founded in 1788 by the toolmaker Hans Jakob Däniker as a craft enterprise in Zurich. Däniker's son Gottfried Reishauer trained as a toolmaker in the business and took over the management in 1824. In 1870, the company was officially registered as a tool factory. In 1882, the "Aktiengesellschaft für Fabrikation Reishauer'scher Werkzeuge" was founded, and the portfolio was expanded to include thread gauges in addition to thread cutting tools.
The step to mechanical engineering (from 1924).
As the thread grinding machines that were currently available on the market did not meet Reishauer's requirements, they designed their own thread grinding machine in 1924. The "RK Gewinde" started to work in the factory in 1928 and marked the step towards becoming a machine tool manufacturer. In 1931, the first in-house made machine for grinding taps was put into operation. Soon Reishauer began to produce the machines not only for his own needs but also to sell them to other companies. This enabled the company to bridge the declining demand for tools in the years after 1929.
The introduction of the continuous generating grinding process and the rise to become an international company (from 1945).
In 1945, the first continuous generating gear grinding machine, ZA, was launched on the market, introducing a form of gear grinding, today known as the Reishauer process. This machine had been preceded by a 15-year development period, as Reishauer wanted to find a more accurate, faster, and cheaper method of manufacturing gears. 1968, the AZA, a new gear grinding machine, was produced. The AZA was based on the same continuous generating process but allowed one person to operate several grinders at the same time, thanks to streamlining the operating process. Reishauer thus took the first step towards automating the gear grinding process. At the same time, production at Reishauer’s customers expanded to gear parts outside machine tool engineering, andt included gears for printing machines, trucks, tractors, and pumps. The electronic generating gearbox, introduced in 1977 with the RZ300E, ensured a level of precision that met the requirements of the aircraft industry. In 1986, the RZ301S enhanced generating grinding with shift grinding, which enabled constant grinding forces and higher profile accuracy. In 1993, the RZ362A, the first high-performance gear grinding machine, made its entry into the automotive industry. With this machine, Reishauer introduces the Low Noise Shifting (LNS) process, which reduced unwanted gear noise. In 1998, the company started its own diamond tool production and laid the foundation for its performance system, the Circle of Competence.
Universal machine and technological development (from 2001).
In 2001, the RZ400, the first universal machine, was launched on the market. It included the electronic generating gearbox developed by Reishauer with interfering signal suppression and extremely high drive rigidity. Furthermore, the RZ400 featured a Windows user interface, safety monitoring of the drive axes, and grinding at 63 m/s cutting speed and dressing of and grinding with multi-start threaded grinding wheels. With the RZ150, developed in 2003, two-spindle technology was introduced, which achieved a further increase in productivity. The machine was specially designed for automotive transmission gears. 2006 saw the launch of the RZ1000, which, just like the RZ400, was particularly adapted to job shops.
In 2008, Reishauer started the production of vitrified grinding wheels and built a new fully automated plant for this purpose in Pfaffnau, the canton of Lucerne, Switzerland. In 2009, the RZ60 series (RZ60, 160, 260) was designed, mainly for the automotive industry, but also for job shops, and further increased the productivity of the Reishauer process. In 2010, Reishauer started the development of clamping devices, which were launched in 2012. In 2014, Reishauer automation was introduced as part of the company's own performance system.
Corporate structure.
Reishauer AG is a subsidiary of Reishauer Beteiligungen AG, to which the German Felsomat AG has been part since 2010. The most important customers are the automotive industry and its suppliers. Reishauer has branches in Germany, France, Japan, China, and the USA.
Products.
Reishauer manufactures gear grinding machines, grinding and dressing tools, clamping systems, and automation solutions. All components are supplied from one source with more than 80% vertical integration. Machines specifically customized for each customer. Reishauer offers complete systems for the production of high-quality gears, including loading and unloading systems for its gear grinding machines. Almost 100% of the products are exported. Reishauer describes its performance system as a Circle of Competence, in which all machine components, tooling, and automation are manufactured in-house.
See also.


Ethernet Exchange

Ethernet exchange is a physical network infrastructure through which Ethernet service providers, carriers and Internet service providers exchange Ethernet traffic between their networks. The Ethernet exchange was created as a neutral meeting place where wireless carriers can connect to multiple Ethernet services in several markets that need access to specific locations though one connection. As service providers and operators continue to grow, they need a network to support the increasing amount of data and video on mobile networks. Thus, allowing Ethernet sellers connecting to an Ethernet exchange immediate access to the buyers and a more basic technical process.
Ethernet exchanges offer an accelerated system for carriers and worldwide service providers to extend market reach and coverage. Many carriers and service providers have adopted this technology due to the refined administration features and lower costs when compared to older wholesale Ethernet interconnectivity solutions.


CAD data exchange

CAD data exchange is a method of drawing data exchange used to translate between different computer-aided design (CAD) authoring systems or between CAD and other downstream CAx systems.
Many companies use different CAD systems and exchange CAD data file format with suppliers, customers, and subcontractors. Such formats are often proprietary. Transfer of data is necessary so that, for example, one organization can be developing a CAD model, while another performs analysis work on the same model; at the same time a third organization is responsible for manufacturing the product.
Since the 1980s, a range of different CAD technologies have emerged. They differ in their application aims, user interfaces, performance levels, and in data structures and data file formats. For interoperability purposes a requirement of accuracy in the data exchange process is of paramount importance and robust exchange mechanisms are needed.
The exchange process targets primarily the geometric information of the CAD data but it can also target other aspects such as metadata, knowledge, manufacturing information, tolerances and assembly structure.
There are three options available for CAD data exchange: direct model translation, neutral file exchange and third-party translators.
CAD data content.
Although initially targeted for the geometric information (wire frame, surfaces, solids and drawings) of a product, nowadays there are other pieces of information that can be retrieved from a CAD file:
The different types of product information targeted by the exchange process may vary throughout the life cycle of the product. At earlier stages of the design process, more emphasis is given to the geometric and design intent aspects of the data exchange while metadata and application data are more important at later stages of the product and process development.
Data exchange options.
There are at least three ways to exchange data between different CAD system: via a hardcopy or image (e.g. TIFF, GIF, JPEG, BMP or PCX, by way of image tracing), CAD-neutral formats or third-party CAD file translators between proprietary file formats. All have their advantages and disadvantages and may be error-prone.
Direct model translation.
Direct data translators provide a direct solution which entails translating the data stored in a product database directly from one CAD system format to another, usually in one step. There usually exists a neutral database in a direct data translator. The structure of the neutral database must be general, governed by the minimum required definitions of any of the modelling data types, and be independent of any vendor format. Major CAD systems, such as SolidWorks, PTC Creo, Siemens NX and CATIA can directly read and/or write other CAD formats, simply by using "File Open" and "File Save As" options. This option is limited by the fact that most CAD formats are proprietary therefore direct translators are typically unidirectional, partially functional and not standardized.
Neutral file exchange.
Neutral file exchange uses an intermediary neutral format to translate data between CAD systems. This method starts from a pre-processor embedded in the original CAD system, which generates the neutral file from the originating CAD format. The target CAD system post-processes the neutral file and converts it into the target native format. Some neutral formats are defined by standards organizations such as IGES and STEP while others are proprietary but still widely used and are regarded as quasi industry standards.
Third-party translators.
Several companies specialize in CAD data translation software that can read from one CAD system and write the information in another CAD system format. There are a handful of companies that provide low-level software toolkits to directly read and write the major CAD file formats. Most CAD developers license these toolkits, to add import and export capabilities to their products. There are also a significant number of companies that use the low-level translation toolkits as the basis for building standalone end-user translation and validation applications. These systems have their own proprietary intermediate format some of which will allow reviewing the data during translation. Some of these translators work stand-alone while others require one or both of the CAD packages installed on the translation machine as they use code (APIs) from these systems to read/write the data.
Some companies also use these low-level toolkits to create import or export plug-ins for other CAD applications.
Data exchange quality.
Data quality can be addressed intrinsically and extrinsically. Intrinsic problems are those related to the CAD model’s structure before any translation process begins, while extrinsic problems relate to those issues appearing during translation. The development of STEP is the best solution to solve the extrinsic problems, extending its current capabilities to support 2-D parametric sections, 3-D parametric assemblies, and history-based modeling. Product data quality is a key issue to avoid intrinsic data exchange problems and simplify the integration of downstream applications in the design chain.
As each CAD system has its own method of describing geometry, both mathematically and structurally, there is always some loss of information when translating data from one CAD data format to another. One example is when the translation occurs between CAD systems using different geometric modeling kernels, in which the translation inconsistencies can lead to anomalies in the data. The intermediate file formats are also limited in what they can describe, and they can be interpreted differently by both the sending and receiving systems. It is, therefore, important when transferring data between systems to identify what needs to be translated. If only the 3D model is required for the downstream process, then only the model description needs to be transferred. However, there are levels of detail. For example: is the data wireframe, surface, or solid; is the topology (BREP) information required; must the face and edge identifications be preserved on subsequent modification; must the feature information and history be preserved between systems; and is PMI annotation to be transferred. With product models, retaining the assembly structure may be required. If drawings need to be translated, the wireframe geometry is normally not an issue; however text, dimensions and other annotation can be an issue, particularly fonts and formats. No matter what data is to be translated, there is also a need to preserve attributes (such as color and layer of graphical objects) and metadata stored within the files.
Some translation methods are more successful than others at translating data between CAD systems. Native formats offer the simple translation of 3D solids, but even so there are few pitfalls to watch out for. If two CAD systems use different representations for one type of geometry at some point the representation must be converted or even discarded, regardless of the type of translation. Modern Neutral formats are designed to solve this problem.
Old neutral formats like IGES can have some translation issues like loss of the original color of the parts, or incorrect position of bodies.
This is no longer the case with modern standards like STEP AP242, which embeds Validation Properties. Validation Properties are key characteristics of the model (Center of Gravity of a solid, wet area of a surface, PMI characteristics or even check points on a shape), stored by the emitting system and checked by the receiving system. This allows to control the quality of the imported data.
Quality of exchange using STEP is so important that regular benchmarks are run by independent associations (AFNeT, PDES, inc., ProSTEP iViP) to check exchanges between various CAD and PLM systems.
Some CAD systems have functionalities to compare geometry of two models. So, user can compare the model before and after translation from one CAD to another one to estimate quality of the translation, and to fix found defects. But often such functionalities can compare only tessellations of two models. It is really hard algorithmic problem to compare topological elements of two 3D models and restore their associativity to show groups of modified faces, because there are very different representation of geometry data in different CAD systems, but sometimes it is possible. For instance, the component LEDAS Geometry Comparison based on C3D kernel can be integrated in CAD system (like Autodesk Inventor,) to compare 3D models and pinpoint all of the differences between them.
MultiCAD Digital Mockups.
Two CAD/CAM/CAE PLM trends have been driving CAD Data Exchange technology. One is the need for close interaction throughout today’s extended multiCAD enterprises. The other is the increased reliance on digital mockups to permit visualization, design in context, simulation and analysis of large scale assemblies prior to the actual manufacture of the physical product. Ongoing advances in data exchange technology have enabled significant fulfillment of those needs.
The ability to visualize medium if not large scale assemblies was one of the early successes of these CAD translation formats. Hardware improvements and the development of lightweight formats supported larger scale assemblies.
Current advances now allow an “Active Mockup.” This technology allows design in context with simulations such as dynamic clearance analysis and automatic generation of motion envelopes. Active mockups allow the edit of components from directly within the multi-CAD assembly. Multiple level-of-detail displays support interactive performance even in huge assemblies.
CAD to CAM Data Exchange.
NC programming typically requires that the geometry received from a CAD system, whether in wireframe, surface, solid or combined formats, be free from any irregularities and inconsistencies that may have occurred in the CAD phase of geometry creation. Data exchange from CAD to CAM must therefore include tools for identifying and repairing those inconsistencies. These tools are typically included in the data exchange software of each CAM solution-set.
In a true PLM environment, CAD to CAM data exchange must provide for more than the transfer of geometry. Product Manufacturing Information, whether generated by the designer for use by manufacturing, or generated by the manufacturing organization for use by design, must be a part of the data exchange system. STEP-NC was designed to carry GD&T and other PMI through CAD and CAM into a CNC.


Log house moulder

A log house moulder is a machine to prepare logs to be suitable for building a log home. In general, the logs are first sawn to a square beam, then the moulder makes the groove. Often fitted to a portable sawmill that enables direct profiling of round or squared logs. The log house moulder is usually powered by electricity, but for portable sawmills they are sometimes using a chainsaw as power head. One of the more common, especially in Europe, is the
Logosol log house moulder.
Other type of log house moulder is a log through-pass machine. Through-pass log home moulders are highly productive and mighty machines able to turn truck load of logs into house logs during a work shift. Barked or debarked green or dry logs are fed into such machine one after other on one side and the machine processes logs, turning them into profiled roundish or squarish house logs, taken from outfeed of the machine. Such log home milling machine can shape logs into different profiles: Swedish cope, Tongue&groove, D-log, bevel-edged logs, etc.
One of moulders of through-pass type are Woodlandia' Rotary Log Moulders (USA, Canada, Russia)


Fixture (tool)

A fixture is a work-holding or support device used in the manufacturing industry. Fixtures are used to securely locate (position in a specific location or orientation) and support the work, ensuring that all parts produced using the fixture will maintain conformity and interchangeability. Using a fixture improves the economy of production by allowing smooth operation and quick transition from part to part, reducing the requirement for skilled labor by simplifying how workpieces are mounted, and increasing conformity across a production run.
Compared with a jig.
A fixture differs from a jig in that when a fixture is used, the tool must move relative to the workpiece; a jig moves the piece while the tool remains stationary.
Purpose.
A fixture's primary purpose is to create a secure mounting point for a workpiece, allowing for support during operation and increased accuracy, precision, reliability, and interchangeability in the finished parts. It also serves to reduce working time by allowing quick set-up, and by smoothing the transition from part to part. It frequently reduces the complexity of a process, allowing for unskilled workers to perform it and effectively transferring the skill of the tool maker to the unskilled worker. Fixtures also allow for a higher degree of operator safety by reducing the concentration and effort required to hold a piece steady.
Economically speaking the most valuable function of a fixture is to reduce labor costs. Without a fixture, operating a machine or process may require two or more operators; using a fixture can eliminate one of the operators by securing the workpiece.
Design.
Fixtures should be designed with economics in mind; the purpose of these devices is often to reduce costs, and so they should be designed in such a way that the cost reduction outweighs the cost of implementing the fixture. It is usually better, from an economic standpoint, for a fixture to result in a small cost reduction for a process in constant use, than for a large cost reduction for a process used only occasionally.
Most fixtures have a solid component, affixed to the floor or to the body of the machine and considered immovable relative to the motion of the machining bit, and one or more movable components known as clamps. These clamps (which may be operated by many different mechanical means) allow workpieces to be easily placed in the machine or removed, and yet stay secure during operation. Many are also adjustable, allowing for workpieces of different sizes to be used for different operations. Fixtures must be designed such that the pressure or motion of the machining operation (usually known as the feed) is directed primarily against the solid component of the fixture. This reduces the likelihood that the fixture will fail, interrupting the operation and potentially causing damage to infrastructure, components, or operators.
Fixtures may also be designed for very general or simple uses. These multi-use fixtures tend to be very simple themselves, often relying on the precision and ingenuity of the operator, as well as surfaces and components already present in the workshop, to provide the same benefits of a specially-designed fixture. Examples include workshop vises, adjustable clamps, and improvised devices such as weights and furniture.
Each component of a fixture is designed for one of two purposes: location or support.
Location.
Locating components ensure the "geometrical stability" of the workpiece. They make sure that the workpiece rests in the correct position and orientation for the operation by addressing and impeding all the degrees of freedom the workpiece possesses.
For locating workpieces, fixtures employ pins (or "buttons"), clamps, and surfaces. These components ensure that the workpiece is positioned correctly, and remains in the same position throughout the operation. Surfaces provide support for the piece, pins allow for precise location at low surface area expense, and clamps allow for the workpiece to be removed or its position adjusted. Locating pieces tend to be designed and built to very tight specifications.
Support.
In designing the locating parts of a fixture, only the "direction" of forces applied by the operation are considered, and not their "magnitude". Locating parts technically support the workpiece, but do not take into account the strength of forces applied by the process and so are usually inadequate to actually secure the workpiece during operation. For this purpose, support components are used.
To secure workpieces and prevent motion during operation, support components primarily use two techniques: positive stops and friction. A positive stop is any immovable component (such as a solid surface or pin) that, by its placement, physically impedes the motion of the workpiece. Support components are more likely to be adjustable than locating components, and normally do not press tightly on the workpiece or provide absolute location.
Support components usually bear the brunt of the forces delivered during the operation. To reduce the chances of failure, support components are usually not also designed as clamps.
For example: 2 heavy metal parts are to be joined with screws and arc welding. Using a fixture will help secure the two separate parts in a designated area for the craftsman to complete the job easily & without the risk of injury.
Types of fixtures.
Fixtures are usually classified according to the machine for which they were designed. The most common two are "milling fixtures" and "drill fixtures".
Milling fixtures.
Milling operations tend to involve large, straight cuts that produce many chips and involve varying force. Locating and supporting areas must usually be large and very sturdy in order to accommodate milling operations; strong clamps are also a requirement. Due to the vibration of the machine, positive stops are preferred over friction for securing the workpiece. For high-volume automated processes, milling fixtures usually involve hydraulic or pneumatic clamps.
Drilling fixtures.
Drilling fixtures cover a wider range of different designs and procedures than milling fixtures. Though workholding for drills is more often provided by jigs, fixtures are also used for drilling operations.
Two common elements of drilling fixtures are the hole and bushing. Holes are often designed into drilling fixtures, to allow space for the drill bit itself to continue through the workpiece without damaging the fixture or drill, or to guide the drill bit to the appropriate point on the workpiece. Bushings are simple bearing sleeves inserted into these holes to protect them and guide the drill bit.
Because drills tend to apply force in only one direction, support components for drilling fixtures may be simpler. If the drill is aligned pointing down, the same support components may compensate for the forces of both the drill and gravity at once. However, though monodirectional, the force applied by drills tends to be concentrated on a very small area. Drilling fixtures must be designed carefully to prevent the workpiece from bending under the force of the drill.


1984–85 UEFA Cup

The 1984–85 UEFA Cup was the 14th season of the UEFA Cup. It was won by Real Madrid, who gained an aggregate victory over Videoton of Hungary in a two-legged final.
First round.
Second leg.
"Videoton won 1–0 on aggregate."
"Queens Park Rangers won 7–0 on aggregate."
"1–1 on aggregate; Universitatea Craiova won 5–3 on penalties."
"Lokomotive Leipzig won 7–3 on aggregate."
"Köln won 3–1 on aggregate."
"Željezničar won 5–2 on aggregate."
"Spartak Moskva won 7–2 on aggregate."
"Dinamo Minsk won 10–0 on aggregate."
"Partizan won 4–0 on aggregate."
"Rijeka won 4–2 on aggregate."
"CSKA Septemvriysko Zname won 4–3 on aggregate."
"Bohemians ČKD Praha won 8–3 on aggregate."
"Manchester United won 5–2 on aggregate."
"PSV Eindhoven won 3–2 on aggregate."
"Widzew Łódź won 2–1 on aggregate."
"Fiorentina won 3–0 on aggregate."
"Borussia Mönchengladbach won 7–3 on aggregate."
"Standard Liège won 3–1 on aggregate."
"Club Brugge won 1–0 on aggregate."
"Olympiacos won 3–2 on aggregate."
"Linzer ASK won 2–0 on aggregate."
"Real Madrid won 5–2 on aggregate."
"Hamburg won 2–0 on aggregate."
"Sporting CP won 4–2 on aggregate."
"Ajax won 14–0 on aggregate."
"Dundee United won 3–1 on aggregate."
"Rangers won 4–3 on aggregate."
"Paris Saint-Germain won 6–2 on aggregate."
"2–2 on aggregate; Anderlecht won on away goals."
"Internazionale won 2–1 on aggregate."
"Sion won 4–2 on aggregate."
"Tottenham Hotspur won 9–0 on aggregate."
Second round.
Second leg.
"Spartak Moskva won 3–1 on aggregate."
"2–2 on aggregate; Dinamo Minsk won 5–3 on penalties."
"1–1 on aggregate; Bohemians ČKD Praha won 4–2 on penalties."
"3–3 on aggregate; Widzew Łódź won on away goals."
"Hamburg won 6–1 on aggregate."
"6–6 on aggregate; Partizan won on away goals."
"Universitatea Craiova won 2–0 on aggregate."
"Anderlecht won 7–3 on aggregate."
"Željezničar won 3–2 on aggregate."
"Köln won 4–1 on aggregate."
"Internazionale won 4–3 on aggregate."
"Dundee United won 7–2 on aggregate."
"Manchester United won 1–0 on aggregate."
"Tottenham Hotspur won 4–2 on aggregate."
"Real Madrid won 4–3 on aggregate."
"Videoton won 5–2 on aggregate."
Third round.
Second leg.
"Željezničar won 4–2 on aggregate."
"Tottenham Hotspur won 3–1 on aggregate."
"Videoton won 5–2 on aggregate."
"Dinamo Minsk won 2–1 on aggregate."
"Köln won 2–1 on aggregate."
"2–2 on aggregate; Internazionale won on away goals."
"Manchester United won 5–4 on aggregate."
"Real Madrid won 6–4 on aggregate."
Quarter-finals.
Second leg.
"1–1 on aggregate; Videoton won 5–4 on penalties."
"Željezničar won 3–1 on aggregate."
"Internazionale won 4–1 on aggregate."
"Real Madrid won 1–0 on aggregate."
Semi-finals.
Second leg.
"Videoton won 4–3 on aggregate."
"Real Madrid won 3–2 on aggregate."
Final.
Second leg.
"Real Madrid won 3–1 on aggregate."


1982–83 UEFA Cup

The 1982–83 UEFA Cup was the 12th edition of the UEFA Cup. It was won by Belgian club Anderlecht on 2–1 aggregate over Portuguese club Benfica.
Association team allocation.
A total of 64 teams from 31 UEFA member associations participate in the 1982–83 UEFA Cup. The association ranking based on the UEFA country coefficients is used to determine the number of participating teams for each association:
Association ranking.
For the 1982–83 UEFA Cup, the associations are allocated places according to their 1981 UEFA country coefficients, which takes into account their performance in European competitions from 1976–77 to 1980–81. As Albania did not play, Italy obtained a special place.
Teams.
The labels in the parentheses show how each team qualified for competition:
First round.
Second leg.
"Sevilla won 6–1 on aggregate."
"Bohemians won 7–1 on aggregate."
"1–1 on aggregate; KSC Lokeren won on away goals."
"Corvinul Hunedoara won 4–1 on aggregate."
"Kaiserslautern won 6–0 on aggregate."
"Saint-Étienne won 4–1 on aggregate."
"FK Sarajevo won 6–4 on aggregate."
"Hajduk Split won 8–1 on aggregate."
"Baník Ostrava won 4–1 on aggregate."
"Śląsk Wrocław won 3–2 on aggregate."
"3–3 on aggregate; Viking won on away goals."
"Anderlecht won 6–1 on aggregate."
"IK Brage won 4–3 on aggregate."
"2–2 on aggregate; IFK Norrköping won on away goals."
"Bordeaux won 6–3 on aggregate."
"3–3 on aggregate; Werder Bremen won on away goals."
"Ferencvárosi won 3–2 on aggregate."
"HFC Haarlem won 5–4 on aggregate."
"2–2 on aggregate; PAOK won on away goals."
"Zürich won 3–2 on aggregate."
"Benfica won 4–2 on aggregate."
"Roma won 4–3 on aggregate."
"Rangers won 2–0 on aggregate."
"Dundee United won 3–1 on aggregate."
"2–2 on aggregate; Napoli won on away goals."
"Servette won 4–0 on aggregate."
"Spartak Moscow won 8–4 on aggregate."
"Universitatea Craiova won 3–2 on aggregate."
"Valencia won 2–1 on aggregate."
"Porto won 3–0 on aggregate."
"Shamrock Rovers won 7–0 on aggregate."
"Köln won 6–0 on aggregate."
Second round.
First leg.
"See also Luzhniki disaster"

Second leg.
"Universitatea Craiova won 5–0 on aggregate.
"FK Sarajevo won 8–4 on aggregate."
"Valencia won 1–0 on aggregate."

"Bohemians won 4–0 on aggregate."
"Werder Bremen won 8–2 on aggregate."
"1–1 on aggregate. Roma won 4–2 on penalties."
"Benfica won 4–1 on aggregate."
"Bordeaux won 5–4 on aggregate."
"FC Zürich won 2–1 on aggregate."
"Kaiserslautern won 4–1 on aggregate."
"Köln won 6–2 on aggregate."
"Spartak Moscow won 5–1 on aggregate."
"Dundee United won 3–1 on aggregate."
"Sevilla won 4–2 on aggregate."
"Anderlecht won 6–3 on aggregate."
"Servette won 7–1 on aggregate."
Third round.
Second leg.
"Universitatea Craiova won 2–1 on aggregate."
"Roma won 2–1 on aggregate."
"Anderlecht won 6–2 on aggregate."
"Bohemians won 4–3 on aggregate."
"Valencia won 2–0 on aggregate."
"Dundee United won 3–2 on aggregate."
"Kaiserslautern won 4–1 on aggregate."
"Benfica won 5–1 on aggregate."
Quarter-finals.
Second leg.
"3–3 on aggregate; Universitatea Craiova won on away goals."
"Anderlecht won 5–2 on aggregate."
"Bohemians won 1–0 on aggregate."
"Benfica won 3–2 on aggregate."
Semi-finals.
Second leg.
"1–1 on aggregate; Benfica won on away goals."
"Anderlecht won 4–1 on aggregate"
Final.
Second leg.
"Anderlecht won 2–1 on aggregate."


1979–80 UEFA Cup

The 1979–80 UEFA Cup was the ninth season of the UEFA Cup, a football competition organised by UEFA for clubs representing its member associations. The competitions was won by Eintracht Frankfurt, who beat Borussia Mönchengladbach on the away goals rule after a 3–3 aggregate draw in the final. All four semi-finalists came from West Germany, and a fifth was eliminated in the quarter-finals. This is the only time all four semi-finalists in a UEFA club competition came from a single nation.
The third club was revoked to Bulgaria and East Germany, and it was assigned to Czechoslovakia. The title holders obtained a place.
First round.
Second leg.
"Zbrojovka Brno won 7–1 on aggregate."
"AGF won 2–1 on aggregate."
"Eintracht Frankfurt won 2–1 on aggregate."
"Aris Thessaloniki won 4–3 on aggregate."
"Dynamo Dresden won 5–1 on aggregate."
"Borussia Mönchengladbach won 4–1 on aggregate."
"Dinamo București won 12–0 on aggregate."
"1–1 on aggregate; Dundee United won on away goals."
"Bayern Munich won 4–2 on aggregate."
"Carl Zeiss Jena won 4–1 on aggregate."
"Dynamo Kyiv won 3–2 on aggregate."
"Grasshoppers won 6–0 on aggregate."
"Monaco won 3–2 on aggregate."
"Feyenoord won 2–0 on aggregate."
"Kaiserslautern won 8–2 on aggregate."
"Red Star Belgrade won 3–1 on aggregate."
"Standard Liège won 2–0 on aggregate."
"Inter Milan won 3–2 on aggregate."
"2–2 on aggregate; Keflavík won on away goals."
"Malmö FF won 4–1 on aggregate."
"Napoli won 2–1 on aggregate."
"Baník Ostrava won 6–2 on aggregate."
"Perugia won 1–0 on aggregate."
"Lokomotiv Sofia won 3–2 on aggregate."
"Diósgyőri VTK won 4–2 on aggregate."
"Ipswich Town won 10–1 on aggregate."
"Sporting CP won 2–0 on aggregate."
"PSV Eindhoven won 1–0 on aggregate."
"Leeds United won 7–0 on aggregate."
"2–2 on aggregate; Stuttgart won on away goals."
"Saint-Étienne won 4–2 on aggregate."
"Universitatea Craiova won 3–1 on aggregate."
Second round.
Second leg.
"Zbrojovka Brno won 5–2 on aggregate."
"Bayern Munich won 5–2 on aggregate."
"Aris Thessaloniki won 4–1 on aggregate."
"Borussia Mönchengladbach won 4–3 on aggregate."
"Eintracht Frankfurt won 3–2 on aggregate."
"Diósgyöri VTK won 4–1 on aggregate."
"1–1 on aggregate; Stuttgart won on away goals."
"Dynamo Kyiv won 2–1 on aggregate."
"Universitatea Craiova won 4–0 on aggregate."
"Feyenoord won 5–1 on aggregate."
"1–1 on aggregate; Grasshoppers won on away goals."
"Lokomotiv Sofia won 5–4 on aggregate."
"Saint-Étienne won 6–2 on aggregate."
"Red Star Belgrade won 6–4 on aggregate."
"Kaiserslautern won 3–1 on aggregate."
"Standard Liège won 3–2 on aggregate."
Third round.
Second leg.
"Saint-Étienne won 7–4 on aggregate."
"Bayern Munich won 4–3 on aggregate."
"Borussia Mönchengladbach won 2–1 on aggregate."
"Kaiserslautern won 8–1 on aggregate."
"Eintracht Frankfurt won 4–2 on aggregate."
"Stuttgart won 5–0 on aggregate."
"2–2 on aggregate; Lokomotiv Sofia won on away goals."
"Zbrojovka Brno won 5–3 on aggregate."
Quarter-finals.
Second leg.
"Bayern Munich won 4–2 on aggregate."
"Borussia Mönchengladbach won 6–1 on aggregate."
"Eintracht Frankfurt won 6–4 on aggregate."
"Stuttgart won 4–1 on aggregate."
Semi-finals.
Second leg.
"Eintracht Frankfurt won 5–3 on aggregate."
"Borussia Mönchengladbach won 3–2 on aggregate."
Final.
Second leg.
"3–3 on aggregate; Eintracht Frankfurt won on away goals."


1978–79 UEFA Cup

The 1978–79 UEFA Cup was won by Borussia Mönchengladbach on aggregate over Red Star Belgrade.
The third club was revoked to Switzerland and Poland, and it was assigned to Bulgaria and East Germany.
First round.
First leg.
"Enzo Ferrero scored an olympic goal."
Second leg.
"Dukla Prague won 2–1 on aggregate."
"1–1 on aggregate. Milan won in a penalty shoot-out."
"Valencia won 5–3 on aggregate."
"Borussia Mönchengladbach won 7–2 on aggregate."
"Argeș Pitești won 5–1 on aggregate."
"Ajax won 3–2 on aggregate."
"Everton won 10–0 on aggregate."
"Lausanne-Sport won 2–0 on aggregate."
"Benfica won 2–0 on aggregate."
"Sporting Gijón won 3–1 on aggregate."
"Braga won 7–3 on aggregate."
"West Bromwich Albion won 6–2 on aggregate."
"6–6 on aggregate, Red Star Belgrade won on away goals rule."
"KuPS won 6–5 on aggregate."
"Stuttgart won 7–3 on aggregate."
"Torpedo Moscow won 7–3 on aggregate."
"Strasbourg won 4–3 on aggregate."
"MSV Duisburg won 10–2 on aggregate."
"Standard Liège won 1–0 on aggregate."
"Esbjerg won 1–0 on aggregate."
"Arsenal won 7–1 on aggregate."
"Carl Zeiss Jena won 3–2 on aggregate."
"1–1 on aggregate, ÍBV won on away goals rule."
"Manchester City won 4–3 on aggregate."
"Hibernian won 3–2 on aggregate."
"Politehnica Timișoara won 3–2 on aggregate."
"Śląsk Wrocław won 7–3 on aggregate."
"Levski Sofia won 4–3 on aggregate."
"Dinamo Tbilisi won 3–1 on aggregate."
"Hajduk Split won 3–2 on aggregate."
"Hertha BSC won 2–1 on aggregate."
"Budapest Honvéd won 8–2 on aggregate."
Second round.
Second leg.
"Ajax won 5–0 on aggregate."
"Budapest Honvéd won 4–2 on aggregate."
"2–2 on aggregate, Dukla Prague won on away goals rule."
"Valencia won 6–4 on aggregate."
"MSV Duisburg won 3–0 on aggregate."
"Stuttgart won 3–2 on aggregate."
"2–2 on aggregate, Arsenal won on away goals rule."
"Hertha BSC won 2–1 on aggregate."
"Śląsk Wrocław won 4–1 on aggregate."
"Esbjerg won 6–1 on aggregate."
"Manchester City won 4–2 on aggregate."
"Milan won 4–1 on aggregate."
"On 23 November 1978, UEFA fined Milan $14,000 for a bribery attempt to the Scottish referee John Gordon and linesmen Rollo Kyle and David McCartney (Italian club took the officials to shop for free the day before the game). Curiously, UEFA did not sanction the referee at all, however, Scottish Football Association suspended him."
"Strasbourg won 2–1 on aggregate."
"West Bromwich Albion won 3–0 on aggregate."
"Borussia Mönchengladbach won 2–0 on aggregate."
"Red Star Belgrade won 2–1 on aggregate."
Third round.
Second leg.
"Manchester City won 5–2 on aggregate."
"Borussia Mönchengladbach won 5–3 on aggregate."
"Budapest Honvéd won 4–3 on aggregate."
"Hertha BSC won 5–2 on aggregate."
"MSV Duisburg won 4–0 on aggregate."
"Red Star Belgrade won 2–1 on aggregate."
"West Bromwich Albion won 3–1 on aggregate."
"Dukla Prague won 5–4 on aggregate."
Quarter-finals.
Second leg.
"4–4 on aggregate, MSV Duisburg won on away goals rule."
"Hertha BSC won 3–2 on aggregate."
"Borussia Mönchengladbach won 4–2 on aggregate."
"Red Star Belgrade won 2–1 on aggregate."
Semi-finals.
Second leg.
"Borussia Mönchengladbach won 6–3 on aggregate."
"2–2 on aggregate, Red Star Belgrade won on away goals rule."
Final.
Second leg.
"Borussia Mönchengladbach won 2–1 on aggregate."


Novellus Systems

Novellus Systems Inc. was a company founded by Brad Mattson that developed, manufactured, sold, and serviced semiconductor equipment used in the fabrication of integrated circuits. It was a supplier of chemical vapor deposition (CVD), plasma-enhanced chemical vapor deposition (PECVD), physical vapor deposition (PVD), electrochemical deposition (ECD), ultraviolet thermal processing (UVTP), and surface preparation equipment used in the manufacturing of semiconductors.
Novellus Systems was founded in 1984 and is headquartered in San Jose, California. The company maintains engineering & manufacturing facilities in Tualatin, Oregon and San Jose, California. Also, Novellus has a component design and software development facility in Bangalore, India.
In December 2011, Novellus agreed to be acquired by Lam Research for $3.3 billion. The acquisition was completed in June 2012.
Product lines.
Novellus' product lines were called ALTUS, ATHENA, GAMMA, INOVA, SABRE, SOLA, SPEED, and VECTOR, SEQUEL and assisted semiconductor companies with manufacturing.


Test engineer

A test engineer is a professional who determines how to create a process that would best test a particular product in manufacturing and related disciplines, in order to assure that the product meets applicable specifications. Test engineers are also responsible for determining the best way a test can be performed in order to achieve adequate test coverage. Often test engineers also serve as a liaison between manufacturing, design engineering, sales engineering and marketing communities as well.
Test engineer expertises.
Test engineers can have different expertise, which depends on what test process they are more familiar with (although many test engineers have full familiarity from the PCB level processes like ICT, JTAG, and AXI) to PCBA and system level processes like board functional test (BFT or FT), burn-in test, system level test (ST). Some of the processes used in manufacturing where a test engineer is needed are:
Early project involvement from design phase.
Ideally, a test engineer's involvement with a product begins with the very early stages of the engineering design process, i.e. the requirements engineering stage and the design engineering stage. Depending on the culture of the firm, these early stages could involve a Product Requirements Document (PRD) and Marketing Requirements Document (MRD)—some of the earliest work done during a new product introduction (NPI).
By working with or as part of the NPI group, a test engineer ensures that a product is designed for both testability and manufacturability. In other words, to make sure that the product can be readily tested and built.
The following are some general rules to ensure testability and manufacturability of a product:
By following the general rules above, test engineers minimize future surprises (like adding extra components, re-layout of the boards, etc.) which drives up costs and development delays of the final product.
Working with cross platform teams, hardware and software team.
Often people take shortcuts to be able to deliver final products. Because of these shortcuts, the product's manufacturability and testability becomes complicated (inability to read and write information, creating deviation from the process, etc.) which impacts the manufacturing complexity of a product. Because of this complexity, bottlenecks in the manufacturing and delivery schedule delays are introduced.
With this in mind, test engineers always get involved in the following reviews as well:
Yield maintenance.
Products' yield plays a very important part during their lifespan. There are usually three stages for a product, engineering, initial production (IP) and full production (FP).
In addition, yields will show if another process needs to be introduced (e.g., because processes already used cannot capture certain test errors). Yields can also decide if an existing test process can be trimmed down (step-wise or time-wise) or even fully eliminated. E.g., if the ESS errors can be captured during the 3rd hour, test time can be cut down from a normal 24 hours down to maybe 4. Or if a process consistently yields 100% during a 15-month period, teams can get together and decide to eliminate that process at all.
Test automation.
Test automation refers to the automation of the process to test a product through the use of machines. Depending on the product, the machines that we are referring to could mean a combination of Automatic Test Equipment (ATE), handler, interface board, and test program that drives the ATE, as with the case of the IC chip testing.
Test automation is a big part of a test engineer's job.
The whole intention of automating the test is as follows:
Overall, this drives manufacturing reliability and quality at the end of the line making sure that all units shipped out to customers are well tested, stressed, filtered out of any errors, and configured properly.
Defining standard test documents.
Following are some of the documents that the test engineers maintain or define:
Contract manufacturer.
A contract manufacturer (CM) also provides a test engineer for their customers. The function of these test engineers varies depending on the level of support they provide for their customers: providing "interactive and first level of defense"-only support or providing partial or ground-up solutions.
Providing interactive and first level-of-defense support.
Providing "interactive and first level-of-defense"-only support is the usual job of the CM TE. Here are some typical job functions for a CM test engineer:
Because of their close involvement with the test line, they monitor the products going through the line and inspect the failed boards to decide if it really failed or if the failure was just caused by some improper test setup. Some examples of these false failures are:
Providing partial or ground up solutions.
There is a small number of companies who prefer to outsource their test engineering work to their corresponding CM. In that case, the CM TEs will be in charge of providing the test automation solution, test fixture design, yield gathering plus the usual interactive and first level of defense for their customers.
Of course, outsourcing test solutions to the CM has its pros and cons.
Some of the advantages are:
Some of the disadvantages are:
Because it is hard to find a test engineer who knows every aspect of testing methodology (from PCB tests like ICT, JTAG test, flying probe test, and X-Ray test to PCBA test which includes writing test automation from functional test to FQA test among others), companies usually outsource part of the development of this missing test piece to their CM. For example, if none of the in-house TEs know much about ICT fixtures, they will ask their CM to develop the ICT test solutions for them instead.


Dicing tape

Dicing tape is a backing tape used during wafer dicing or some other microelectronic substrate separation, the cutting apart of pieces of semiconductor or other material following wafer or module microfabrication. The tape holds the pieces of the substrate, in case of a wafer called as die, together during the cutting process, mounting them to a thin metal frame. The dies/substrate pieces are removed from the dicing tape later on in the electronics manufacturing process.
Tape types.
Dicing tape can be made of PVC, polyolefin, or polyethylene backing material with an adhesive to hold the wafer or substrate in place. In some cases dicing tape will have a release liner that will be removed prior to mounting the tape to the backside of the wafers, with a variety of adhesive strengths, designed for various wafer/substrate sizes and materials.


Gas tungsten arc welding

Gas tungsten arc welding (GTAW), also known as tungsten inert gas (TIG) welding, is an arc welding process that uses a non-consumable tungsten electrode to produce the weld. The weld area and electrode are protected from oxidation or other atmospheric contamination by an inert shielding gas (argon or helium). A filler metal is normally used, though some welds, known as "autogenous welds", or "fusion welds" do not require it. When helium is used, this is known as heliarc welding. A constant-current welding power supply produces electrical energy, which is conducted across the arc through a column of highly ionized gas and metal vapors known as a plasma. TIG welding is most commonly used to weld thin sections of stainless steel and non-ferrous metals such as aluminum, magnesium, and copper alloys. The process grants the operator greater control over the weld than competing processes such as shielded metal arc welding and gas metal arc welding, allowing stronger, higher-quality welds. However, TIG welding is comparatively more complex and difficult to master, and furthermore, it is significantly slower than most other welding techniques. A related process, plasma arc welding, uses a slightly different welding torch to create a more focused welding arc and as a result is often automated.
Development.
After the discovery of the short pulsed electric arc in 1801 by Humphry Davy and of the continuous electric arc in 1802 by Vasily Petrov, arc welding developed slowly. C. L. Coffin had the idea of welding in an inert gas atmosphere in 1890, but even in the early 20th century, welding non-ferrous materials such as aluminum and magnesium remained difficult because these metals react rapidly with the air, resulting in porous, dross-filled welds. Processes using flux-covered electrodes did not satisfactorily protect the weld area from contamination. To solve the problem, bottled inert gases were used in the beginning of the 1930s. A few years later, a direct current, gas-shielded welding process emerged in the aircraft industry for welding magnesium.
In early 1940s Northrop Aircraft was developing an experimental aircraft from magnesium designated XP-56, for which Vladimir Pavlecka, Tom Piper and Russell Meredith developed a welding process named Heliarc because it used a tungsten electrode arc and helium as a shielding gas (the torch design was patented by Meredith in 1941). It is now often referred to as tungsten inert gas welding (TIG), especially in Europe, but the American Welding Society's official term is gas tungsten arc welding (GTAW). Linde Air Products developed a wide range of air-cooled and water-cooled torches, gas lenses to improve shielding, and other accessories that increased the use of the process. Initially, the electrode overheated quickly and, despite tungsten's high melting temperature, particles of tungsten were transferred to the weld. To address this problem, the polarity of the electrode was changed from positive to negative, but the change made it unsuitable for welding many non-ferrous materials. Finally, the development of alternating current units made it possible to stabilize the arc and produce high quality aluminum and magnesium welds.
Developments continued during the following decades. Linde developed water-cooled torches that helped prevent overheating when welding with high currents. During the 1950s, as the process continued to gain popularity, some users turned to carbon dioxide as an alternative to the more expensive welding atmospheres consisting of argon and helium, but this proved unacceptable for welding aluminum and magnesium because it reduced weld quality, so it is rarely used with GTAW today. The use of any shielding gas containing an oxygen compound, such as carbon dioxide, quickly contaminates the tungsten electrode, making it unsuitable for the TIG process.
In 1953, a new process based on GTAW was developed, called plasma arc welding. It affords greater control and improves weld quality by using a nozzle to focus the electric arc, but is largely limited to automated systems, whereas GTAW remains primarily a manual, hand-held method. Development within the GTAW process has continued as well, and today a number of variations exist. Among the most popular are the pulsed-current, manual programmed, hot-wire, dabber, and increased penetration GTAW methods.
Operation.
Manual gas tungsten arc welding is a relatively difficult welding method, due to the coordination required by the welder. Similar to torch welding, GTAW normally requires two hands, since most applications require that the welder manually feed a filler metal into the weld area with one hand while manipulating the welding torch in the other. Maintaining a short arc length, while preventing contact between the electrode and the workpiece, is also important.
To strike the welding arc, a high-frequency generator (similar to a Tesla coil) provides an electric spark. This spark is a conductive path for the welding current through the shielding gas and allows the arc to be initiated while the electrode and the workpiece are separated, typically about apart.
Once the arc is struck, the welder moves the torch in a small circle to create a welding pool, the size of which depends on the size of the electrode and the amount of current. While maintaining a constant separation between the electrode and the workpiece, the operator then moves the torch back slightly and tilts it backward about 10–15 degrees from vertical. Filler metal is added manually to the front end of the weld pool as it is needed.
Welders often develop a technique of rapidly alternating between moving the torch forward (to advance the weld pool) and adding filler metal. The filler rod is withdrawn from the weld pool each time the electrode advances, but it is always kept inside the gas shield to prevent oxidation of its surface and contamination of the weld. Filler rods composed of metals with a low melting temperature, such as aluminum, require that the operator maintain some distance from the arc while staying inside the gas shield. If held too close to the arc, the filler rod can melt before it makes contact with the weld puddle. As the weld nears completion, the arc current is often gradually reduced to allow the weld crater to solidify and prevent the formation of crater cracks at the end of the weld.
The physics of GTAW involves several complex processes, including thermodynamics, plasma physics, and fluid dynamics. The non-consumable tungsten electrode can be operated as a Cathode or Anode and is used to produce an electric arc between the electrode and the workpiece. In order to initially create the arc, the welding area is flooded with inert gas and a high strike voltage (typically 1 kV per 1 mm) is generated by the welding machine to overcome the electric resistivity of the atmosphere surrounding the welding area. With the arc established, the voltage is lowered and current flows between the work piece and electrode. Despite the high temperatures of this electric arc, the main heat transfer mechanism in GTAW is the joule heating resulting from this current flow.
Safety.
Welders wear protective clothing, including light and thin leather gloves and protective long sleeve shirts with high collars, to avoid exposure to strong ultraviolet light. Due to the absence of smoke in GTAW, the electric arc light is not covered by fumes and particulate matter as in stick welding or shielded metal arc welding, and thus is a great deal brighter, subjecting operators to strong ultraviolet light. The welding arc has a different range and strength of UV light wavelengths from sunlight, but the welder is very close to the source and the light intensity is very strong. Potential arc light damage includes accidental flashes to the eye or arc eye and skin damage similar to strong sunburn. Operators wear opaque helmets with dark eye lenses and full head and neck coverage to prevent this exposure to UV light. Modern helmets often feature a liquid crystal-type face plate that self-darkens upon exposure to the bright light of the struck arc. Transparent welding curtains, made of a strongly colored polyvinyl chloride plastic film, are often used to shield nearby workers and bystanders from exposure to the UV light from the electric arc.
Welders are also often exposed to dangerous gases and particulate matter. While the process doesn't produce smoke, the brightness of the arc in GTAW can break down surrounding air to form ozone and nitric oxides. The ozone and nitric oxides react with lung tissue and moisture to create nitric acid and ozone burn. Ozone and nitric oxide levels are moderate, but exposure duration, repeated exposure, and the quality and quantity of fume extraction, and air change in the room must be monitored. Welders who do not work safely can contract emphysema and oedema of the lungs, which can lead to early death. Similarly, the heat from the arc can cause poisonous fumes to form from cleaning and degreasing materials. Cleaning operations using these agents should not be performed near the site of welding, and proper ventilation is necessary to protect the welder.
Applications.
While the aerospace industry is one of the primary users of gas tungsten arc welding, the process is used in a number of other areas. Many industries use GTAW for welding thin workpieces, especially nonferrous metals. It is used extensively in the manufacture of space vehicles and is also frequently employed to weld small-diameter, thin-wall tubing such as that used in the bicycle industry. In addition, GTAW is often used to make root or first-pass welds for piping of various sizes. In maintenance and repair work, the process is commonly used to repair tools and dies, especially components made of aluminum and magnesium. Because the weld metal is not transferred directly across the electric arc like most open arc welding processes, a vast assortment of welding filler metal is available to the welding engineer. In fact, no other welding process permits the welding of so many alloys in so many product configurations. Filler metal alloys, such as elemental aluminum and chromium, can be lost through the electric arc from volatilization. This loss does not occur with the GTAW process. Because the resulting welds have the same chemical integrity as the original base metal or match the base metals more closely, GTAW welds are highly resistant to corrosion and cracking over long time periods, making GTAW the welding procedure of choice for critical operations like sealing spent nuclear fuel canisters before burial.
Quality.
Gas tungsten arc welding, because it affords greater control over the weld area than other welding processes, can produce high-quality welds when performed by skilled operators. Maximum weld quality is assured by maintaining cleanliness—all equipment and materials used must be free from oil, moisture, dirt and other impurities, as these cause weld porosity and consequently a decrease in weld strength and quality. To remove oil and grease, alcohol or similar commercial solvents may be used, while a stainless steel wire brush or chemical process can remove oxides from the surfaces of metals like aluminum. Rust on steels can be removed by first grit blasting the surface and then using a wire brush to remove any embedded grit. These steps are especially important when negative polarity direct current is used, because such a power supply provides no cleaning during the welding process, unlike positive polarity direct current or alternating current. To maintain a clean weld pool during welding, the shielding gas flow should be sufficient and consistent so that the gas covers the weld and blocks impurities in the atmosphere. GTAW in windy or drafty environments increases the amount of shielding gas necessary to protect the weld, increasing the cost and making the process unpopular outdoors.
The level of heat input also affects weld quality. Low heat input, caused by low welding current or high welding speed, can limit penetration and cause the weld bead to lift away from the surface being welded. If there is too much heat input, however, the weld bead grows in width while the likelihood of excessive penetration and spatter (emission of small, unwanted droplets of molten metal) increases. Additionally, if the welding torch is too far from the workpiece the shielding gas becomes ineffective, causing porosity within the weld. This results in a weld with pinholes, which is weaker than a typical weld.
If the amount of current used exceeds the capability of the electrode, tungsten inclusions in the weld may result. Known as tungsten spitting, this can be identified with radiography and can be prevented by changing the type of electrode or increasing the electrode diameter. In addition, if the electrode is not well protected by the gas shield or the operator accidentally allows it to contact the molten metal, it can become dirty or contaminated. This often causes the welding arc to become unstable, requiring that the electrode be ground with a diamond abrasive to remove the impurity.
Equipment.
The equipment required for the gas tungsten arc welding operation includes a welding torch utilizing a non-consumable tungsten electrode, a constant-current welding power supply, and a shielding gas source.
Welding torch.
GTAW welding torches are designed for either automatic or manual operation and are equipped with cooling systems using air or water. The automatic and manual torches are similar in construction, but the manual torch has a handle while the automatic torch normally comes with a mounting rack. The angle between the centerline of the handle and the centerline of the tungsten electrode, known as the head angle, can be varied on some manual torches according to the preference of the operator. Air cooling systems are most often used for low-current operations (up to about 200 A), while water cooling is required for high-current welding (up to about 600 A). The torches are connected with cables to the power supply and with hoses to the shielding gas source and where used, the water supply.
The internal metal parts of a torch are made of hard alloys of copper or brass so it can transmit current and heat effectively. The tungsten electrode must be held firmly in the center of the torch with an appropriately sized collet, and ports around the electrode provide a constant flow of shielding gas. Collets are sized according to the diameter of the tungsten electrode they hold. The body of the torch is made of heat-resistant, insulating plastics covering the metal components, providing insulation from heat and electricity to protect the welder.
The size of the welding torch nozzle depends on the amount of shielded area desired. The size of the gas nozzle depends upon the diameter of the electrode, the joint configuration, and the availability of access to the joint by the welder. The inside diameter of the nozzle is preferably at least three times the diameter of the electrode, but there are no hard rules. The welder judges the effectiveness of the shielding and increases the nozzle size to increase the area protected by the external gas shield as needed. The nozzle must be heat resistant and thus is normally made of alumina or a ceramic material, but fused quartz, a high purity glass, offers greater visibility. Devices can be inserted into the nozzle for special applications, such as gas lenses or valves to improve the control shielding gas flow to reduce turbulence and the introduction of contaminated atmosphere into the shielded area. Hand switches to control welding current can be added to the manual GTAW torches.
Power supply.
Gas tungsten arc welding uses a constant current power source, meaning that the current (and thus the heat flux) remains relatively constant, even if the arc distance and voltage change. This is important because most applications of GTAW are manual or semiautomatic, requiring that an operator hold the torch. Maintaining a suitably steady arc distance is difficult if a constant voltage power source is used instead since it can cause dramatic heat variations and make welding more difficult.
The preferred polarity of the GTAW system depends largely on the type of metal being welded. Direct current with a negatively charged electrode (DCEN) is often employed when welding steels, nickel, titanium, and other metals. It can also be used in automatic GTAW of aluminum or magnesium when helium is used as a shielding gas. The negatively charged electrode generates heat by emitting electrons, which travel across the arc, causing thermal ionization of the shielding gas and increasing the temperature of the base material. The ionized shielding gas flows toward the electrode, not the base material, and this can allow oxides to build on the surface of the weld. Direct current with a positively charged electrode (DCEP) is less common, and is used primarily for shallow welds since less heat is generated in the base material. Instead of flowing from the electrode to the base material, as in DCEN, electrons go the other direction, causing the electrode to reach very high temperatures. To help it maintain its shape and prevent softening, a larger electrode is often used. As the electrons flow toward the electrode, ionized shielding gas flows back toward the base material, cleaning the weld by removing oxides and other impurities and thereby improving its quality and appearance.
Alternating current, commonly used when welding aluminum and magnesium manually or semi-automatically, combines the two direct currents by making the electrode and base material alternate between positive and negative charge. This causes the electron flow to switch directions constantly, preventing the tungsten electrode from overheating while maintaining the heat in the base material. Surface oxides are still removed during the electrode-positive portion of the cycle and the base metal is heated more deeply during the electrode-negative portion of the cycle. Some power supplies enable operators to use an unbalanced alternating current wave by modifying the exact percentage of time that the current spends in each state of polarity, giving them more control over the amount of heat and cleaning action supplied by the power source. In addition, operators must be wary of rectification, in which the arc fails to reignite as it passes from straight polarity (negative electrode) to reverse polarity (positive electrode). To remedy the problem, a square wave power supply can be used, as can high-frequency to encourage arc stability.
Electrode.
The electrode used in GTAW is made of tungsten or a tungsten alloy, because tungsten has the highest melting temperature among pure metals, at . As a result, the electrode is not consumed during welding, though some erosion (called burn-off) can occur. Electrodes can have either a clean finish or a ground finish—clean finish electrodes have been chemically cleaned, while ground finish electrodes have been ground to a uniform size and have a polished surface, making them optimal for heat conduction. The diameter of the electrode can vary between , and their length can range from .
A number of tungsten alloys have been standardized by the International Organization for Standardization and the American Welding Society in ISO 6848 and AWS A5.12, respectively, for use in GTAW electrodes, and are summarized in the adjacent table.
Filler metals are also used in nearly all applications of GTAW, the major exception being the welding of thin materials. Filler metals are available with different diameters and are made of a variety of materials. In most cases, the filler metal in the form of a rod is added to the weld pool manually, but some applications call for an automatically fed filler metal, which often is stored on spools or coils.
Shielding gas.
As with other welding processes such as gas metal arc welding, shielding gases are necessary in GTAW to protect the welding area from atmospheric gases such as nitrogen and oxygen, which can cause fusion defects, porosity, and weld metal embrittlement if they come in contact with the electrode, the arc, or the welding metal. The gas also transfers heat from the tungsten electrode to the metal, and it helps start and maintain a stable arc.
The selection of a shielding gas depends on several factors, including the type of material being welded, joint design, and desired final weld appearance. Argon is the most commonly used shielding gas for GTAW, since it helps prevent defects due to a varying arc length. When used with alternating current, argon shielding results in high weld quality and good appearance. Another common shielding gas, helium, is most often used to increase the weld penetration in a joint, to increase the welding speed, and to weld metals with high heat conductivity, such as copper and aluminum. A significant disadvantage is the difficulty of striking an arc with helium gas, and the decreased weld quality associated with a varying arc length.
Argon-helium mixtures are also frequently utilized in GTAW, since they can increase control of the heat input while maintaining the benefits of using argon. Normally, the mixtures are made with primarily helium (often about 75% or higher) and a balance of argon. These mixtures increase the speed and quality of the AC welding of aluminum, and also make it easier to strike an arc. Another shielding gas mixture, argon-hydrogen, is used in the mechanized welding of light gauge stainless steel, but because hydrogen can cause porosity, its uses are limited. Similarly, nitrogen can sometimes be added to argon to help stabilize the austenite in austenitic stainless steels and increase penetration when welding copper. Due to porosity problems in ferritic steels and limited benefits, however, it is not a popular shielding gas additive.
Materials.
Gas Tungsten Arc Welding is most commonly used to weld stainless steel and nonferrous materials, such as aluminum and magnesium, but it can be applied to nearly all metals, with a notable exception being zinc and its alloys. Its applications involving carbon steels are limited not because of process restrictions, but because of the existence of more economical steel welding techniques, such as gas metal arc welding and shielded metal arc welding. Furthermore, GTAW can be performed in a variety of other-than-flat positions, depending on the skill of the welder and the materials being welded.
Aluminum and magnesium.
Aluminum and magnesium are most often welded using alternating current, but the use of direct current is also possible, depending on the properties desired. Before welding, the work area should be cleaned and may be preheated to for aluminum or to a maximum of for thick magnesium workpieces to improve penetration and increase travel speed. Alternating current can provide a self-cleaning effect, removing the thin, refractory aluminum oxide layer that forms on aluminum metal within minutes of exposure to air. This oxide layer must be removed for welding to occur. When alternating current is used, pure tungsten electrodes or zirconiated tungsten electrodes are preferred over thoriated electrodes, as the latter are more likely to "spit" electrode particles across the welding arc into the weld. Blunt electrode tips are preferred, and pure argon shielding gas should be employed for thin workpieces. Introducing helium allows for greater penetration in thicker workpieces, but can make arc starting difficult.
Direct current of either polarity, positive or negative, can be used to weld aluminum and magnesium as well. Direct current with a negatively charged electrode (DCEN) allows for high penetration. Argon is commonly used as a shielding gas for DCEN welding of aluminum. Shielding gases with high helium contents are often used for higher penetration in thicker materials. Thoriated electrodes are suitable for use in DCEN welding of aluminum. Direct current with a positively charged electrode (DCEP) is used primarily for shallow welds, especially those with a joint thickness of less than . A thoriated tungsten electrode is commonly used, along with pure argon shielding gas.
Steels.
For GTAW of carbon and stainless steels, the selection of filler material is important to prevent excessive porosity. Oxides on the filler material and workpieces must be removed before welding to prevent contamination, and immediately prior to welding, alcohol or acetone should be used to clean the surface. Preheating is generally not necessary for mild steels less than one inch thick, but low alloy steels may require preheating to slow the cooling process and prevent the formation of martensite in the heat-affected zone. Tool steels should also be preheated to prevent cracking in the heat-affected zone. Austenitic stainless steels do not require preheating, but martensitic and ferritic chromium stainless steels do. A DCEN power source is normally used, and thoriated electrodes, tapered to a sharp point, are recommended. Pure argon is used for thin workpieces, but helium can be introduced as thickness increases.
Dissimilar metals.
Welding dissimilar metals often introduce new difficulties to GTAW welding, because most materials do not easily fuse to form a strong bond. However, welds of dissimilar materials have numerous applications in manufacturing, repair work, and the prevention of corrosion and oxidation. In some joints, a compatible filler metal is chosen to help form the bond, and this filler metal can be the same as one of the base materials (for example, using a stainless steel filler metal with stainless steel and carbon steel as base materials), or a different metal (such as the use of a nickel filler metal for joining steel and cast iron). Very different materials may be coated or "buttered" with a material compatible with particular filler metal, and then welded. In addition, GTAW can be used in cladding or overlaying dissimilar materials.
When welding dissimilar metals, the joint must have an accurate fit, with proper gap dimensions and bevel angles. Care should be taken to avoid melting excessive base material. Pulsed current is particularly useful for these applications, as it helps limit the heat input. The filler metal should be added quickly, and a large weld pool should be avoided to prevent dilution of the base materials.
Process variations.
Pulsed-current.
In the pulsed-current mode, the welding current rapidly alternates between two levels. The higher current state is known as the pulse current, while the lower current level is called the background current. During the period of pulse current, the weld area is heated and fusion occurs. Upon dropping to the background current, the weld area is allowed to cool and solidify. Pulsed-current GTAW has a number of advantages, including lower heat input and consequently a reduction in distortion and warpage in thin workpieces. In addition, it allows for greater control of the weld pool, and can increase weld penetration, welding speed, and quality. A similar method, manual programmed GTAW, allows the operator to program a specific rate and magnitude of current variations, making it useful for specialized applications.
Dabber.
The dabber variation is used to precisely place weld metal on thin edges. The automatic process replicates the motions of manual welding by feeding a cold or hot filler wire into the weld area and dabbing (or oscillating) it into the welding arc. It can be used in conjunction with pulsed current, and is used to weld a variety of alloys, including titanium, nickel, and tool steels. Common applications include rebuilding seals in jet engines and building up saw blades, milling cutters, drill bits, and mower blades.


Plasma arc welding

Plasma arc welding (PAW) is an arc welding process similar to gas tungsten arc welding (GTAW). The electric arc is formed between an electrode (which is usually but not always made of sintered tungsten) and the workpiece. The key difference from GTAW is that in PAW, the electrode is positioned within the body of the torch, so the plasma arc is separated from the shielding gas envelope. The plasma is then forced through a fine-bore copper nozzle which constricts the arc and the plasma exits the orifice at high velocities (approaching the speed of sound) and a temperature approaching 28,000 °C (50,000 °F) or higher.
Arc plasma is a temporary state of a gas. The gas gets ionized by electric current passing through it and it becomes a conductor of electricity. In ionized state, atoms are broken into electrons (−) and cations (+) and the system contains a mixture of ions, electrons and highly excited atoms. The degree of ionization may be between 1% and greater than 100% (possible with double and triple degrees of ionization). Such states exist as more electrons are pulled from their orbits.
The energy of the plasma jet and thus the temperature depends upon the electrical power employed to create arc plasma. A typical value of temperature obtained in a plasma jet torch is on the order of ), compared to about ) in ordinary electric welding arc. All welding arcs are (partially ionized) plasmas, but the one in plasma arc welding is a constricted arc plasma.
Just as oxy-fuel torches can be used for either welding or cutting, so too can plasma torches.
Concept.
Plasma arc welding is an arc welding process wherein coalescence is produced by the heat obtained from a constricted arc setup between a tungsten/alloy tungsten electrode and the water-cooled (constricting) nozzle (non-transferred arc) or between a tungsten/alloy tungsten electrode and the job (transferred arc). The process employs two inert gases, one forms the arc plasma and the second shields the arc plasma. Filler metal may or may not be added.
History.
The plasma arc welding and cutting process was invented by Robert M. Gage in 1953 and patented in 1957. The process was unique in that it could achieve precision cutting and welding on both thin and thick metals. It was also capable of spray coating hardening metals onto other metals. One example was the spray coating of the turbine blades of the moon bound Saturn rocket.
Principle of operation.
Plasma arc welding is an advanced form of tungsten inert gas (TIG) welding. In the case of TIG, it is an open arc shielded by argon or helium, whereas plasma uses a special torch where the nozzle is used to constrict the arc while the shielding gas is separately supplied by the torch. The arc is constricted with the help of a water-cooled small diameter nozzle which squeezes the arc, increases its pressure, temperature and heat intensely and thus improves arc stability, arc shape and heat transfer characteristics.
Plasma arcs are formed using gas in two forms; laminar (low pressure and low flow) and turbulent (high pressure and high flow).
The gases used are argon, helium, hydrogen or a mixture of these. In the case of plasma welding, laminar flow (low pressure and low flow of plasma gas) is employed to ensure that the molten metal is not blown out of the weld zone.
The non-transferred arc (pilot arc) is employed during plasma-welding to initiate the welding process. The arc is formed between the electrode(-) and the water-cooled constricting nozzle (+). A non-transferred arc is initiated by using a high-frequency unit in the circuit. After the initial high-frequency start, the pilot arc (low current) is formed between the elect by employing a low current. After the main arc is struck, the nozzle is neutral or in case of welding-mesh using micro plasma, there can be an option given to have a continuous pilot arc. A transferred arc possesses high energy density and plasma jet velocity. Depending on the current used and flow of gas, it can be employed to cut and melt metals.
Microplasma uses current between 0.1 and 10 amps and is used foils, bellow, and thin sheets. This is an autogenous process and normally does not use filler wire or powder.
Medium plasma uses current between 10 and 100 amps and is used for higher-thickness plate welding with filler wire or autogenous up to plates and metal deposition (hardfacing) using specialised torches and powder feeders (PTA) using metal powders.
High-current plasma above 100 amps is used with filler wires welding at high travel speeds.
Other applications of plasma are plasma-cutting, heating, deposition of diamond films (Kurihara et al. 1989), material processing, metallurgy (production of metals and ceramics), plasma-spraying, and underwater cutting.
Equipment.
The equipment needed in plasma arc welding along with their functions are as follows:
Typical welding parameters for plasma arc welding are as follows:
Current 50 to 350 amps, voltage 27 to 31 volts, gas flow rates 2 to 40 liters/minute (lower range for orifice gas and higher range for outer shielding gas), direct current electrode negative (DCEN) is normally employed for plasma arc welding except for the welding of aluminum in which cases water-cooled electrode is preferable for reverse-polarity welding, i.e. direct-current electrode positive (DCEP).
For cutting purposes, a mixture of argon and hydrogen (10-30%) or that of nitrogen may be used. Hydrogen, because of its dissociation into atomic form and thereafter recombination generates temperatures above those attained by using argon or helium alone. In addition, hydrogen provides a reducing atmosphere, which helps in preventing oxidation of the weld and its vicinity. Care must be taken, as hydrogen diffusing into the metal can lead to embrittlement in some metals and steels.
Process description.
The technique of work-piece cleaning and filler-metal addition is similar to that in TIG welding. Filler metal is added at the leading edge of the weld pool. Filler metal is not required in making root-pass weld.
Type of Joints: For welding work piece up to 25 mm thick, joints like square butt, J or V are employed. Plasma welding is used to make both key hole and non-key hole types of welds.
Making a non-key-hole weld: The process can make non-key-hole welds on work pieces having thickness 2.4 mm and under.
Making a keyhole welds: An outstanding characteristic of plasma arc welding, owing to exceptional penetrating power of plasma jet, is its ability to produce keyhole welds in work piece having thickness from 2.5 mm to 25 mm. A keyhole effect is achieved through right selection of current, nozzle-orifice diameter and travel speed, which create a forceful plasma jet to penetrate completely through the work piece. Plasma jet in no case should expel the molten metal from the joint. The major advantages of the keyhole technique are the ability to penetrate rapidly through relatively thick root sections and to produces a uniform under bead without mechanical backing. Also, the ratio of the depth of penetration to the width of the weld is much higher, resulting narrower weld and heat-affected zone. As the weld progresses, base metal ahead the keyhole melts, flow around the same solidifies and forms the weld bead. Key-holing aids deep penetration at faster speeds and produces high-quality bead. While welding thicker pieces, in laying others than root run, and using filler metal, the force of plasma jet is reduced by suitably controlling the amount of orifice gas.
Plasma arc welding is an advancement over the GTAW process. This process uses a non-consumable tungsten electrode and an arc constricted through a fine-bore copper nozzle. PAW can be used to join all metals that are weldable with GTAW (i.e., most commercial metals and alloys). Difficult-to-weld in metals by PAW include bronze, cast iron, lead and magnesium.
Several basic PAW process variations are possible by varying the current, plasma gas-flow rate, and the orifice diameter, including:
Process variables.
Gases.
At least two separate (and possibly three) flows of gas are used in PAW:
These gases can all be same, or of differing composition.
Other plasma arc processes.
Depending upon the design of the torch (e.g., orifice diameter), electrode design, gas type and velocities, and the current levels, several variations of the plasma process are achievable, including:
Plasma arc cutting.
When used for cutting, the plasma gas flow is increased so that the deeply penetrating plasma jet cuts through the material and molten material is removed as cutting dross. PAC differs from oxy-fuel cutting in that the plasma process operates by using the arc to melt the metal whereas in the oxy-fuel process, the oxygen oxidizes the metal and the heat from the exothermic reaction melts the metal. Unlike oxy-fuel cutting, the PAC process can be applied to cutting metals which form refractory oxides such as stainless steel, cast iron, aluminum and other non-ferrous alloys. Since PAC was introduced by Praxair Inc. at the American Welding Society show in 1954, many process refinements, gas developments, and equipment improvements have occurred.
External links.
Plasma Arc Welding
Microplasma welding
Arc spray welding


Roll trailer

A roll trailer is a trailer platform that requires towing by a powered vehicle. It is commonly used for the transport of heavy static goods and materials in the maritime shipping industry. Roll trailers are similar to shipping containers, however, they have a set of rear wheels.
Overview.
Roll trailers are a common equipment used in ports and on board of roll-on/roll-off ships, to facilitate the shipping of unmovable commodities and oversize load from one port to another.
Standard lengths of roll trailers are , in line with twenty-foot equivalent unit shipping containers, but can also be found in lengths of . The standard payloads of roll trailers vary from 40 to 120 tons, and the tare of the trailer varies from 7 to 10 tons.
The trailer has a steel structure and a hardwood surface, plus a front pocket for towing by tugmaster gooseneck, and side handles for applying lashing hooks.
Operations.
Goods are usually placed on roll trailers by forklift or shore crane, secured with lashing or chains, and then towed on/off board via tugmaster tractor. When empty, they can be stacked like shipping containers.
Every trailer has a unique identification number stamped on sides, composed of four letters and seven digits, directly related to the manufacturer company abbreviation name, the payload capacity and its length size.
All the main shipping lines have an owned fleet of roll trailers available to be offered to shippers for moving heavy static cargo.
Additionally, all main roll trailers manufacturers tend to lease extra equipment during peak times, by charging a daily hire fee to the shipping lines.
Once in the port, after a short "free time" period, roll trailers are subject to demurrage charges, to cover storage and detention fees and to ensure consignees swiftly unload their cargo, temporary positioned on the shipping line's trailers during the sea passage.
As per standard practice, and opposite to shipping containers, roll trailers are not permitted to exit the ports, with receivers requested to collect their goods inside the terminals.


Assembly line feeding problem

The assembly line feeding problem (abbr. ALFP) describes a problem in operations management concerned with finding the optimal way of feeding parts to assembly stations. For this, various cost elements may be taken into account and every part is assigned to a policy, i.e., a way of feeding parts to an assembly line. The most common policies are:
These policies differ with respect to the way parts are brought to the line as well as in the way parts are handled before they are brought to the line. E.g., in line stocking, parts are brought to the line directly in the way they are stored in the warehouse. In the other policies, quantities are reduced (boxed supply) and different part variants are sorted in the order of demand (sequencing, stationary, and traveling kitting).
History.
The problem was formally introduced by Bozer and McGinnis in 1992 by means of a descriptive cost model. Since then, many contributions have been made in both, quantitative and qualitative manners. E.g., a more qualitative contribution is done by Hua and Johnson investigating important aspects of the problem, whereas more recent contributions focus rather on quantitative aspects and use mathematical optimization to solve this assignment problem to optimality
Mathematical problem statement.
formula_1
This model minimizes the costs formula_2 when assigning all parts (index:i) to a feeding policy (index:p) at all stations (index:s) formula_3, if there is a demand for a part at a station formula_4. Using a certain policy at a station formula_5 incurs some cost formula_6 as well as some other costs formula_7 are incurred when a policy is used at any station formula_8.
All assembly line feeding problems of this type have been proven to be NP-hard


Camelot Management Consultants AG

Camelot Management Consultants AG is an international consulting firm with focus on Supply Chain Management. 320 consultants work directly for Camelot Management Consultants and around 1.400 consultants work in Camelot's partner organizations in eight branch offices. CEO of Camelot Management Consultants was Josef Packowski.
Services.
Camelot Management Consultants is specialized in Value Chain Management in the core industries Chemicals & Petrochemicals, Pharmaceuticals & Life Sciences and Consumer Goods. The company combines management consulting and implementation in the areas of (excerpt): Supply Chain Management, Finance & Performance Management, Sourcing & Procurement, Logistics & Distribution, Master Data Management, Transport Management and Strategic Information Management.
LEAN Supply Chain Planning.
Camelot Management Consultants has developed a Supply Chain Management approach LEAN Supply Chain Planning. T
Awards.
Camelot Management Consultants has received several awards in the last years. In 2012 the management consultancy received an award in the category “Supply Chain Management” in the competition “Best of Consulting” run by the German business magazine "Wirtschaftswoche", in 2013 the technology partner Camelot ITLab was honored for the best “IT Management” in the competition. In 2014 Camelot Management Consultants also received the award by "brandeins" in the competition “Beste Berater 2014 (Best Consultants 2014)”. In 2013, Camelot Management Consultants was awarded as “Top Consultant” for being one of the best mid-sized consulting firm. The Hochschule Bonn-Rhein-Sieg awarded the unit Camelot ITLab 2014 with the certificate “Top-Consultant” for one of the best IT consultancy firms. In 2014 Camelot ITLab also received the “INNOVATIONSPREIS-IT” in the category “Best of ERP 2014”.


MacPherson strut

The MacPherson strut is a type of automotive suspension system that uses the top of a telescopic damper as the upper steering pivot. It is widely used in the front suspension of modern vehicles. The name comes from American automotive engineer Earle S. MacPherson, who invented and developed the design.
History.
Earle S. MacPherson was appointed the chief engineer of Chevrolet's Light Car project in 1945. He was tasked with developing a new, smaller car for the immediate post-war market, an effort that led to the Chevrolet Cadet.
The Cadet was poised to be a groundbreaking vehicle, and the three prototypes that had been built by 1946 displayed a wide range of innovations. One of these was a revolutionary new independent suspension system that featured what is now known as a MacPherson strut. The Cadet was slated to be the first production vehicle with MacPherson struts, but the project was cancelled in 1947 and never saw commercial production. This was in large part due to GM's concerns about the Cadet's forecasted profit margins.
After the Cadet project was shelved, a disgruntled MacPherson left GM to join Ford. Patents were filed in 1947 ( for GM) and in 1949 ( for Ford), with the latter patent citing designs by Guido Fornaca of FIAT in the mid-1920s.
MacPherson's new strut design may have taken inspirations from other earlier designs as well. The strut suspension of the pre-war Stout Scarab could have been an influence, and long-travel struts in aircraft landing gear were well known by that time. The French Cottin-Desgouttes utilized a similar design, albeit with less sophisticated leaf springs, but the Cottin-Desgouttes front suspension was in turn inspired by a 1904 design by American engineer J. Walter Christie.
MacPherson designed the strut for all four wheels, but it is normally used for the front suspension only, where it provides a steering pivot as well as a suspension mounting for the wheel.
The first production car to use MacPherson struts is often cited incorrectly as the French 1949 Ford Vedette, but it was developed before MacPherson, with an independent front suspension based on wishbones and an upper coil spring. Only in 1954, after the Vedette factory had been purchased by Simca, did the revised Simca Vedette switch to using front struts.
Following MacPherson's arrival at Ford, the first production car to feature MacPherson struts was the British-built 1950 Ford Consul and the later Zephyr.
Design.
A MacPherson strut uses a wishbone, or a substantial compression link stabilized by a secondary link, which provides a mounting point for the hub carrier or axle of the wheel. The lower arm system provides both lateral and longitudinal location of the wheel. The upper part of the hub carrier is rigidly fixed to the bottom of the outer part of the strut proper. That slides up and down the inner part of it, which extends upwards directly to a mounting in the body shell of the vehicle. The line from the top mount of the strut to the bottom ball joint on the control arm gives the steering axis inclination. The axis of the strut may be angled inwards from the steering axis at the bottom, to clear the tyre, which makes the bottom follow an arc when steering.
The MacPherson strut benefited from introduction of unitary construction, because its design requires substantial vertical space and a strong top mount, which unibody construction can provide. Unibody construction also distributes suspension stresses. The strut will usually carry both the coil spring, on which the body is suspended, and the shock absorber, which is usually in the form of a cartridge mounted within the strut (see coilover). The strut can also have the steering arm built into the lower outer portion. The whole assembly is very simple and can be pre-assembled into a unit. As well, the elimination of the upper control arm allows for more width in the engine compartment, which is useful for smaller cars, particularly with transverse-mounted engines, such as most front wheel drive vehicles have. The assembly can be further simplified, if needed, by substituting an anti-roll bar (torsion bar) for the radius arm. For those reasons, it has become almost ubiquitous with low cost manufacturers. Furthermore, it offers an easy method to set suspension geometry.
Many modern versions replace the lower control arm with a wishbone. An anti-roll bar is optional and, if present, is attached by a ball-jointed rod to the spring-damper, or by a ball or elastomerically jointed rod to the wishbone.
Advantages and disadvantages.
Because MacPherson struts are packaged with a significant structure in the front crash structure of the car, it is easier to engineer cars that pass more stringent small overlap crashes with struts, as opposed to those with a double wishbone suspension. Notable examples include the Honda Accord and Civic, as well as the Mercedes E-Class, all of which adopted struts to improve crash performance. The overall simplicity of the design also means there are fewer joints in the suspension to wear, so there is less decline in handling and steering feel over time. Inverted monotube struts can also provide extra rigidity in the front suspension, as seen in the Porsche 911 GT3 and Cayman GT4, as well as the Subaru Impreza WRX STI. Finally, struts can package more efficiently than other types of front suspension, which allows for significant front cargo space in rear/mid-engined cars, such as the Porsche 911 and Boxster.
Geometric analysis shows the assembly cannot allow vertical movement of the wheel without some degree of either camber angle change, sideways movement, or both. It is not generally considered to give as good handling as a double wishbone or multi-link suspension, because it allows the engineers less freedom to choose camber change and roll center. Cars that have cockpit adjustable ride height generally cannot have MacPherson struts because of the camber changes that are an unavoidable part of the design. Ride suffers because the shock absorber has almost the same vertical motion as the wheel, so there is relatively little leverage to break the stiction in the seals. A standard single pivot MacPherson strut also tends to have positive scrub where the center of the steering axis is offset from the center of the front tires, which results in torque steer.
Despite the drawbacks, the MacPherson strut set-up is still used on some high performance cars, because they tend to have relatively small suspension travel, and so do not have the same kinematic problems.
Up until the 1989 model year (964), Porsche 911 used a similar strut design that did not have coil springs, using torsion bar suspension instead. Since then, all Porsche 911s have had front MacPherson struts, except the 992-based 911 GT3, which uses a double wishbone.
In recent years, General Motors and Ford have introduced a modified strut set-up, "Hi-Per Strut" and "Revoknuckle" respectively, that split the strut into two components that handle the up-and-down flexibility and steering dynamics separately. The benefits of this design are greater surface contact and reduction in torque steer. The drawbacks are the additional weight and cost, but it is less expensive than either a double wishbone or multi-link setup. Honda introduced another variation strut set-up, called "dual-axis", which is used in the suspension design of the Civic Type-R. Another variant of the MacPherson strut is the double pivot front suspension, which splits the lower wishbone into two while retaining the standard upright design of the MacPherson strut. That allows for better control of steering geometry and scrub radius, while allowing for a larger brake assembly.


Force chain

In the study of the physics of granular materials, a force chain consists of a set of particles within a compressed granular material that are held together and jammed into place by a network of mutual compressive forces.
Between these chains are regions of low stress whose grains are shielded for the effects of the grains above by vaulting and arching. A set of interconnected force chains is known as a force network. Force networks visualise inter-particle forces, which is particularly informative for spherical particle systems. For non-spherical particle systems force chain networks benefit from being supplemented by traction chain networks. Traction chains visualise inter-particle tractions, which give additional insight in inter-particle contact not captured by force chains, in particular, the role of contact area over which inter-particle forces act.
Force networks are an emergent phenomenon that are created by the complex interaction of the individual grains of material and the patterns of pressure applied within the material. Force chains can be shown to have fractal properties.
Force chains have been investigated both experimentally, through the construction of specially instrumented physical models, and through computer simulation.