Friction stir welding

Friction stir welding (FSW) is a solid-state joining process that uses a non-consumable tool to join two facing workpieces without melting the workpiece material. Heat is generated by friction between the rotating tool and the workpiece material, which leads to a softened region near the FSW tool. While the tool is traversed along the joint line, it mechanically intermixes the two pieces of metal, and forges the hot and softened metal by the mechanical pressure, which is applied by the tool, much like joining clay, or dough. It is primarily used on wrought or extruded aluminium and particularly for structures which need very high weld strength. FSW is capable of joining aluminium alloys, copper alloys, titanium alloys, mild steel, stainless steel and magnesium alloys. More recently, it was successfully used in welding of polymers. In addition, joining of dissimilar metals, such as aluminium to magnesium alloys, has been recently achieved by FSW. Application of FSW can be found in modern shipbuilding, trains, and aerospace applications.
The general idea was patented in the Soviet Union by one Yu. Klimenko in 1967, but it wasn't developed into a commercial technology back then. It was experimentally proven and commercialized at The Welding Institute (TWI) in the UK in 1991. TWI held patents on the process, the first being the most descriptive.
Principle of operation.
Friction stir welding is performed with a rotating cylindrical tool which has a profiled pin (also known a probe) having a diameter smaller than the diameter of its shoulder. During welding the tool is fed into a butt joint between two clamped workpieces, until the probe pierces into the workpiece and its shoulder touches the surface of the workpieces. The probe is slightly shorter than the weld depth required, with the tool shoulder riding atop the work surface. After a short dwell time, the tool is moved forward along the joint line at the pre-set welding speed.
Frictional heat is generated between the wear-resistant tool and the work pieces. This heat, along with that generated by the mechanical mixing process and the adiabatic heat within the material, cause the stirred materials to soften without melting. As the tool is moved forward, a special profile on the probe forces plasticised material from the leading face to the rear, where the high forces assist in a forged consolidation of the weld.
This process of the tool traversing along the weld line in a plasticised tubular shaft of metal results in severe solid-state deformation involving dynamic recrystallization of the base material.
Micro-structural features.
The solid-state nature of the FSW process, combined with its unusual tool shape and asymmetric speed profile, results in a highly characteristic micro-structure. The micro-structure can be broken up into the following zones:
Advantages and limitations.
The solid-state nature of FSW leads to several advantages over fusion welding methods, as problems associated with cooling from the liquid phase are avoided. Issues such as porosity, solute redistribution, solidification cracking and liquation cracking do not arise during FSW. In general, FSW has been found to produce a low concentration of defects and is very tolerant to variations in parameters and materials.
Nevertheless, FSW is associated with a number of unique defects if it isn't done properly. Insufficient weld temperatures, due to low rotational speeds or high traverse speeds, for example, mean that the weld material is unable to accommodate the extensive deformation during welding. This may result in long, tunnel-like defects running along the weld, which may occur on the surface or subsurface. Low temperatures may also limit the forging action of the tool and so reduce the continuity of the bond between the material from each side of the weld. The light contact between the material has given rise to the name "kissing bond". This defect is particularly worrying, since it is very difficult to detect using nondestructive methods such as X-ray or ultrasonic testing. If the pin is not long enough or the tool rises out of the plate, then the interface at the bottom of the weld may not be disrupted and forged by the tool, resulting in a lack-of-penetration defect. This is essentially a notch in the material, which can be a potential source of fatigue cracks.
A number of potential advantages of FSW over conventional fusion-welding processes have been identified:
However, some disadvantages of the process have been identified:
Important welding parameters.
Tool design.
The design of the tool is a critical factor, as a good tool can improve both the quality of the weld and the maximal possible welding speed.
It is desirable that the tool material be sufficiently strong, tough, and hard wearing at the welding temperature. Further, it should have a good oxidation resistance and a low thermal conductivity to minimise heat loss and thermal damage to the machinery further up the drive train. Hot-worked tool steel such as AISI H13 has proven perfectly acceptable for welding aluminium alloys within thickness ranges of 0.5–50 mm but more advanced tool materials are necessary for more demanding applications such as highly abrasive metal matrix composites or higher-melting-point materials such as steel or titanium.
Improvements in tool design have been shown to cause substantial improvements in productivity and quality. TWI has developed tools specifically designed to increase the penetration depth and thus increasing the plate thicknesses that can be successfully welded. An example is the "whorl" design that uses a tapered pin with re-entrant features or a variable-pitch thread to improve the downwards flow of material. Additional designs include the Triflute and Trivex series. The Triflute design has a complex system of three tapering, threaded re-entrant flutes that appear to increase material movement around the tool. The Trivex tools use a simpler, non-cylindrical, pin and have been found to reduce the forces acting on the tool during welding.
The majority of tools have a concave shoulder profile, which acts as an escape volume for the material displaced by the pin, prevents material from extruding out of the sides of the shoulder and maintains downwards pressure and hence good forging of the material behind the tool. The Triflute tool uses an alternative system with a series of concentric grooves machined into the surface, which are intended to produce additional movement of material in the upper layers of the weld.
Widespread commercial applications of friction stir welding process for steels and other hard alloys such as titanium alloys will require the development of cost-effective and durable tools. Material selection, design and cost are important considerations in the search for commercially useful tools for the welding of hard materials. Work is continuing to better understand the effects of tool material's composition, structure, properties and geometry on their performance, durability and cost.
Tool rotation and traverse speeds.
There are two tool speeds to be considered in friction-stir welding; how fast the tool rotates and how quickly it traverses along the interface. These two parameters have considerable importance and must be chosen with care to ensure a successful and efficient welding cycle. The relationship between the rotation speed, the welding speed and the heat input during welding is complex, but in general, it can be said that increasing the rotation speed or decreasing the traverse speed will result in a hotter weld. In order to produce a successful weld, it is necessary that the material surrounding the tool is hot enough to enable the extensive plastic flow required and minimize the forces acting on the tool. If the material is too cold, then voids or other flaws may be present in the stir zone and in extreme cases the tool may break.
Excessively high heat input, on the other hand, may be detrimental to the final properties of the weld. Theoretically, this could even result in defects due to the liquation of low-melting-point phases (similar to liquation cracking in fusion welds). These competing demands lead onto the concept of a "processing window": the range of processing parameters viz. tool rotation and traverse speed, that will produce a good quality weld. Within this window the resulting weld will have a sufficiently high heat input to ensure adequate material plasticity but not so high that the weld properties are excessively deteriorated.
Tool tilt and plunge depth.
The plunge depth is defined as the depth of the lowest point of the shoulder below the surface of the welded plate and has been found to be a critical parameter for ensuring weld quality. Plunging the shoulder below the plate surface increases the pressure below the tool and helps ensure adequate forging of the material at the rear of the tool. Tilting the tool by 2–4 degrees, such that the rear of the tool is lower than the front, has been found to assist this forging process. The plunge depth needs to be correctly set, both to ensure the necessary downward pressure is achieved and to ensure that the tool fully penetrates the weld. Given the high loads required, the welding machine may deflect and so reduce the plunge depth compared to the nominal setting, which may result in flaws in the weld. On the other hand, an excessive plunge depth may result in the pin rubbing on the backing plate surface or a significant undermatch of the weld thickness compared to the base material. Variable-load welders have been developed to automatically compensate for changes in the tool displacement, while TWI have demonstrated a roller system that maintains the tool position above the weld plate.
Welding forces.
During welding, a number of forces will act on the tool:
In order to prevent tool fracture and to minimize excessive wear and tear on the tool and associated machinery, the welding cycle is modified so that the forces acting on the tool are as low as possible, and abrupt changes are avoided. In order to find the best combination of welding parameters, it is likely that a compromise must be reached, since the conditions that favour low forces (e.g. high heat input, low travel speeds) may be undesirable from the point of view of productivity and weld properties.
Flow of material.
Early work on the mode of material flow around the tool used inserts of a different alloy, which had a different contrast to the normal material when viewed through a microscope, in an effort to determine where material was moved as the tool passed.
The data was interpreted as representing a form of in-situ extrusion, where the tool, backing plate and cold base material form the "extrusion chamber", through which the hot, plasticised material is forced. In this model the rotation of the tool draws little or no material around the front of the probe; instead, the material parts in front of the pin and passes down either side. After the material has passed the probe, the side pressure exerted by the "die" forces the material back together, and consolidation of the joint occurs, as the rear of the tool shoulder passes overhead and the large down force forges the material.
More recently, an alternative theory has been advanced that advocates considerable material movement in certain locations. This theory holds that some material does rotate around the probe, for at least one rotation, and it is this material movement that produces the "onion-ring" structure in the stir zone. The researchers used a combination of thin copper strip inserts and a "frozen pin" technique, where the tool is rapidly stopped in place. They suggested that material motion occurs by two processes:
The primary advantage of this explanation is that it provides a plausible explanation for the production of the onion-ring structure.
The marker technique for friction stir welding provides data on the initial and final positions of the marker in the welded material. The flow of material is then reconstructed from these positions. Detailed material flow field during friction stir welding can also be calculated from theoretical considerations based on fundamental scientific principles. Material flow calculations are routinely used in numerous engineering applications. Calculation of material flow fields in friction stir welding can be undertaken both using comprehensive numerical simulations or simple but insightful analytical equations. The comprehensive models for the calculation of material flow fields also provide important information such as geometry of the stir zone and the torque on the tool. The numerical simulations have shown the ability to correctly predict the results from marker experiments and the stir zone geometry observed in friction stir welding experiments.
Generation and flow of heat.
For any welding process, it is, in general, desirable to increase the travel speed and minimise the heat input, as this will increase productivity and possibly reduce the impact of welding on the mechanical properties of the weld. At the same time, it is necessary to ensure that the temperature around the tool is sufficiently high to permit adequate material flow and prevent flaws or tool damage.
When the traverse speed is increased, for a given heat input, there is less time for heat to conduct ahead of the tool, and the thermal gradients are larger. At some point the speed will be so high that the material ahead of the tool will be too cold, and the flow stress too high, to permit adequate material movement, resulting in flaws or tool fracture. If the "hot zone" is too large, then there is scope to increase the traverse speed and hence productivity.
The welding cycle can be split into several stages, during which the heat flow and thermal profile will be different:
Heat generation during friction-stir welding arises from two main sources: friction at the surface of the tool and the deformation of the material around the tool. The heat generation is often assumed to occur predominantly under the shoulder, due to its greater surface area, and to be equal to the power required to overcome the contact forces between the tool and the workpiece. The contact condition under the shoulder can be described by sliding friction, using a friction coefficient μ and interfacial pressure "P", or sticking friction, based on the interfacial shear strength at an appropriate temperature and strain rate. Mathematical approximations for the total heat generated by the tool shoulder "Q"total have been developed using both sliding and sticking friction models:
where ω is the angular velocity of the tool, "R"shoulder is the radius of the tool shoulder, and "R"pin is that of the pin. Several other equations have been proposed to account for factors such as the pin, but the general approach remains the same.
A major difficulty in applying these equations is determining suitable values for the friction coefficient or the interfacial shear stress. The conditions under the tool are both extreme and very difficult to measure. To date, these parameters have been used as "fitting parameters", where the model works back from measured thermal data to obtain a reasonable simulated thermal field. While this approach is useful for creating process models to predict, for example, residual stresses, it is less useful for providing insights into the process itself.
Applications.
The FSW process has initially been patented by TWI in most industrialised countries and licensed for over 183 users. Friction stir welding and its variants friction stir spot welding and friction stir processing are used for the following industrial applications: shipbuilding and offshore,
aerospace, automotive, rolling stock for railways, general fabrication, robotics, and computers.
Shipbuilding and offshore.
Two Scandinavian aluminium extrusion companies were the first to apply FSW commercially to the manufacture of fish freezer panels at Sapa in 1996, as well as deck panels and helicopter landing platforms at Marine Aluminium Aanensen. Marine Aluminium Aanensen subsequently merged with Hydro Aluminium Maritime to become Hydro Marine Aluminium. Some of these freezer panels are now produced by Riftec and Bayards. In 1997 two-dimensional friction stir welds in the hydrodynamically flared bow section of the hull of the ocean viewer vessel "The Boss" were produced at Research Foundation Institute with the first portable FSW machine. The "Super Liner Ogasawara" at Mitsui Engineering and Shipbuilding is the largest friction stir welded ship so far. The "Sea Fighter" of Nichols Bros and the "Freedom"-class Littoral Combat Ships contain prefabricated panels by the FSW fabricators Advanced Technology and Friction Stir Link, Inc. respectively. The "Houbei"-class missile boat has friction stir welded rocket launch containers of China Friction Stir Centre. HMNZS "Rotoiti" in New Zealand has FSW panels made by Donovans in a converted milling machine. Various companies apply FSW to armor plating for amphibious assault ships.
Aerospace.
United Launch Alliance applies FSW to the Delta II, Delta IV, Atlas V, and the new Vulcan expendable launch vehicles along with their Cryogenic Upper Stages, and the first of these with a friction stir welded interstage module was launched in 1999. The process was also used for the Space Shuttle external tank, for Ares I until the project was canceled in 2012, the SLS Core which replaced the Ares, and for the Orion Crew Vehicle test article and the current model of the Orion at NASA, as well as Falcon 1 and Falcon 9 rockets at SpaceX. The toe nails for ramp of Boeing C-17 Globemaster III cargo aircraft by Advanced Joining Technologies and the cargo barrier beams for the Boeing 747 Large Cargo Freighter were the first commercially produced aircraft parts. FAA-approved wings and fuselage panels of the Eclipse 500 aircraft were made at Eclipse Aviation, and this company delivered 259 friction stir welded business jets, before they were forced into Chapter 7 liquidation. Floor panels for Airbus A400M military aircraft are now made by Pfalz Flugzeugwerke and Embraer used FSW for the Legacy 450 and 500 Jets Friction stir welding also is employed for fuselage panels on the Airbus A380. BRÖTJE-Automation uses friction stir welding for gantry production machines developed for the aerospace sector, as well as other industrial applications.
Automotive.
Aluminium engine cradles and suspension struts for stretched Lincoln Town Cars were the first automotive parts that were friction stir welded at Tower Automotive, who use the process also for the engine tunnel of the Ford GT. A spin-off of this company is called Friction Stir Link, Inc. and successfully exploits the FSW process, e.g. for the flatbed trailer "Revolution" of Fontaine Trailers. In Japan FSW is applied to suspension struts at Showa Denko and for joining of aluminium sheets to galvanized steel brackets for the boot (trunk) lid of the Mazda MX-5. Friction stir spot welding is successfully used for the bonnet (hood) and rear doors of the Mazda RX-8 and the boot lid of the Toyota Prius. Wheels are friction stir welded at Simmons Wheels, UT Alloy Works and Fundo. Rear seats for the Volvo V70 are friction stir welded at Sapa, HVAC pistons at Halla Climate Control and exhaust gas recirculation coolers at Pierburg. Tailor welded blanks are friction stir welded for the Audi R8 at Riftec. The B-column of the Audi R8 Spider is friction stir welded from two extrusions at Hammerer Aluminium Industries in Austria. The front subframe of the 2013 Honda Accord was friction stir welded to join aluminum and steel halves.
Railways.
Since 1997 roof panels were made from aluminium extrusions at Hydro Marine Aluminium with a bespoke 25 m long FSW machine, e.g. for DSB class SA-SD trains of Alstom LHB. Curved side and roof panels for the Victoria line trains of London Underground, side panels for Bombardier Electrostar trains at Sapa Group and side panels for Alstom's British Rail Class 390 Pendolino trains are made at Sapa Group. Japanese commuter and express A-trains, and British Rail Class 395 trains are friction stir welded by Hitachi, while Kawasaki applies friction stir spot welding to roof panels and Sumitomo Light Metal produces Shinkansen floor panels. Innovative FSW floor panels are made by Hammerer Aluminium Industries in Austria for the Stadler Kiss double decker rail cars, to obtain an internal height of 2 m on both floors and for the new car bodies of the Wuppertal Suspension Railway.
Heat sinks for cooling high-power electronics of locomotives are made at Sykatek, EBG, Austerlitz Electronics, EuroComposite, Sapa and , and are the most common application of FSW due to the excellent heat transfer.
Fabrication.
Façade panels and cathode sheets are friction stir welded at AMAG and Hammerer Aluminium Industries, including friction stir lap welds of copper to aluminium. Bizerba meat slicers, Ökolüfter HVAC units and Siemens X-ray vacuum vessels are friction stir welded at Riftec. Vacuum valves and vessels are made by FSW at Japanese and Swiss companies. FSW is also used for the encapsulation of nuclear waste at SKB in 50-mm-thick copper canisters. Pressure vessels from ø1 m semispherical forgings of 38.1 mm thick aluminium alloy 2219 at Advanced Joining Technologies and Lawrence Livermore Nat Lab. Friction stir processing is applied to ship propellers at Friction Stir Link, Inc. and to hunting knives by DiamondBlade. Bosch uses it in Worcester for the production of heat exchangers.
Robotics.
KUKA Robot Group has adapted its KR500-3MT heavy-duty robot for friction stir welding via the DeltaN FS tool. The system made its first public appearance at the EuroBLECH show in November 2012.
Personal computers.
Apple applied friction stir welding on the 2012 iMac to effectively join the bottom to the back of the device.
Joining of aluminum 3D printing material.
FSW is proven able to be used as one of the methods to join the metal 3D printing materials. By using proper FSW tools and correct parameter setting a sound and defect-free weld can be produced in order to joint the metal 3D printing materials. Besides, the FSW tools must be harder than the materials that need to weld. The most important parameters in FSW are the rotation of probe, traverse speed, spindle tilt angle and target depth. The weld joint efficiency of FSW on the 3D printing metal can reach up to 83.3% compared to its base materials strength.


Higashi-Fuji Technical Center

 is a Toyota research and development facility in Susono, Shizuoka, Japan. The facility was established in November 1966.
Notably, the center contains an advanced driving simulation housed inside a diameter dome with an actual car inside. The simulator is used to analyse driver behaviors in order to improve safety. Higashi-Fuji also includes a crash test building.


Intelligent maintenance system

An intelligent maintenance system (IMS) is a system that utilizes collected data from machinery in order to predict and prevent potential failures in them. The occurrence of failures in machinery can be costly and even catastrophic. In order to avoid failures, there needs to be a system which analyzes the behavior of the machine and provides alarms and instructions for preventive maintenance. Analyzing the behavior of the machines has become possible by means of advanced sensors, data collection systems, data storage/transfer capabilities and data analysis tools. These are the same set of tools developed for prognostics. The aggregation of data collection, storage, transformation, analysis and decision making for smart maintenance is called an intelligent maintenance system (IMS).
Definition.
An intelligent maintenance system is a system that utilizes data analysis and decision support tools to predict and prevent the potential failure of machines. The recent advancement in information technology, computers, and electronics have facilitated the design and implementation of such systems.
The key research elements of intelligent maintenance systems consist of:
E-manufacturing and e-maintenance.
With evolving applications of tether-free communication technologies (e.g. Internet) e-intelligence is having a larger impact on industries. Such impact has become a driving force for companies to shift the manufacturing operations from traditional factory integration practices towards an e-factory and e-supply chain philosophy. Such change is transforming the companies from local factory automation to global business automation. The goal of e-manufacturing is, from the plant floor assets, to predict the deviation of the quality of the products and possible loss of any equipment. This brings about the predictive maintenance capability of the machines.
The major functions and objectives of e-manufacturing are: “(a) provide a transparent, seamless and automated information exchange process to enable an only handle information once (OHIO) environment; (b) improve the utilization of plant floor assets using a holistic approach combining the tools of predictive maintenance techniques; (c) links entire supply chain management (SCM) operation and asset optimization; and (d) deliver customer services using the latest predictive intelligence methods and tether-free technologies”.
The e-Maintenance infrastructure consists of several information sectors:


Thulin N

The Thulin N was a prototype Swedish scout aircraft built in the late 1910s.
Design and development.
The Thulin N was a two-seat biplane. Both the upper and lower wings were fitted with knuckles which were connected by a push rod. The fuselage was provided with an open cockpit where one was placed in a tandem location. The fuselage is made of a lattice construction of welded steel pipes . The wheel ground was fixed with a spur spring under the height knob. Although the Swedish military asked Thulin to use a 150-hp Benz engine as the powerplant, Thulin opted for a Thulin G rotary engine.


Ramp-up

Ramp-up is a term used in economics and business to describe an increase in a firm's production ahead of anticipated increases in product demand. Alternatively, ramp-up describes the period from completed initial product development to maximum capacity utilization, characterized by product and process experimentation and improvements.
Ramp-up in the first sense often occurs when a company strikes a deal with a distributor, retailer, or producer, which will substantially increase product demand. For example, in June, 2008, after launching a joint venture with Guangzhou Automobile, Toyota announced that it would "ramp up" production in China to meet expected increases in market demand by constructing a plant in Guangdong, which would produce some 120,000 additional Camry sedans. In the consumer electronics industry, manufacturers often ramp-up production in the early fall to meet demand during the holiday selling season.
As ramp-up is typical in early stages of firm or market development, the term and process is widely associated with venture capital, which seek to rapidly increase rate of return on investment, just prior to exit. For example, Wrightspeed, the producer of the X1 electric car prototype, began to seek out capital in order to hire on 50 well-trained employees in order to "ramp up" production in anticipation of sales successes.
Ramp up may also refer to how quickly dispatchable generation from power plants can increase, and ramp down by how quickly it can decrease whilst still remaining operational (not shutting down), with "ramp" being either way.


Shearing (manufacturing)

Shearing, also known as die cutting, is a process that cuts stock without the formation of chips or the use of burning or melting. Strictly speaking, if the cutting blades are straight the process is called shearing; if the cutting blades are curved then they are shearing-type operations. The most commonly sheared materials are in the form of sheet metal or plates. However, rods can also be sheared. Shearing-type operations include blanking, piercing, roll slitting, and trimming. It is used for metal, fabric, paper and plastics.
Principle.
A punch (or moving blade) is used to push a workpiece against the die (or fixed blade), which is fixed. Usually, the clearance between the two is 5 to 40% of the thickness of the material, but dependent on the material. Clearance is defined as the separation between the blades, measured at the point where the cutting action takes place and perpendicular to the direction of blade movement. It affects the finish of the cut (burr) and the machine's power consumption. This causes the material to experience highly localized shear stresses between the punch and die. The material will then fail when the punch has moved 15 to 60% of the thickness of the material because the shear stresses are greater than the shear strength of the material and the remainder of the material is torn.
Two distinct sections can be seen on a sheared workpiece, the first part being plastic deformation and the second being fractured. Because of normal inhomogeneities in materials and inconsistencies in clearance between the punch and die, the shearing action does not occur in a uniform manner. The fracture will begin at the weakest point and progress to the next weakest point until the entire workpiece has been sheared; this is what causes the rough edge. The rough edge can be reduced if the workpiece is clamped from the top with a die cushion. Above a certain pressure, the fracture zone can be completely eliminated. However, the sheared edge of the workpiece will usually experience work-hardening and cracking. If the workpiece has too much clearance, then it may experience roll-over or heavy burring.
Tolerances and surface finish.
When shearing a sheet, the typical tolerance is +0.1 inch or −0.1 inch, but it is feasible to get the tolerance to within +0.005 inch or −0.005 inch. While shearing a bar and angle, the typical tolerance is +0.06 inch or −0.06 inch, but it is possible to get the tolerance to +0.03 inch or −0.03 inches. Surface finishes typically occur within the 250 to 1000 microinches range but can range from 125 to 2000 microinches. A secondary operation is required if one wants better surfaces than this.


Soldering iron

A soldering iron is a hand tool used in soldering. It supplies heat to melt solder so that it can flow into the joint between two workpieces.
A soldering iron is composed of a heated metal tip (the "bit") and an insulated handle. Heating is often achieved electrically, by passing an electric current (supplied through an electrical cord or battery cables) through a resistive heating element. Cordless irons can be heated by combustion of gas stored in a small tank, often using a catalytic heater rather than a flame. Simple irons, less commonly used today than in the past, were simply a large copper "bit" on a handle, heated in a flame.
Solder melts at approximately . Soldering irons are designed to reach a temperature range of .
Soldering irons are most often used for installation, repairs, and limited production work in electronics assembly. High-volume production lines use other soldering methods. Large irons may be used for soldering joints in sheet metal objects. Less common uses include pyrography (burning designs into wood) and plastic welding (as an alternative to ultrasonic welding).
History.
Before the development of electric soldering irons, the typical soldering iron consisted of a copper block, with an appropriately shaped point, supported on an iron rod and held in a wood handle. Immediately before use, the iron was heated over a fire or in a charcoal brazier, and it had to be reheated whenever it became too cool for use. Soldering irons were primarily used by tinsmiths and coppersmiths to work with thin sheet metal.
A large copper block was required in order to have sufficient thermal capacity to provide
useful heat after removal from the fire, and copper is expensive. This led to the development of
soldering irons that had a small copper tip attached to an inexpensive cast-iron block. Some irons even had removable and replaceable copper tips.
The first electric soldering iron had a very lightweight platinum tip heated by electric current flowing through the tip itself. By 1889, electric soldering irons were being developed with a resistance wire wrapped around the back end of the copper head and enclosed in a protective shell. Alternatively, the heating element could be enclosed in a relatively light-weight hollow copper head.
In 1894, the American Electrical Heater Company began manufacturing electrical soldering irons on a large scale in Detroit. They started producing them shortly after American Beauty released their line of soldering irons.
In 1905, "Scientific American Magazine," published a tutorial on making a soldering iron that
clearly explains how early irons were made.
In 1921, a German company founded by Ernst Sachs developed an electrical soldering iron similar to American Electrical Heater Company iron.
Types.
Simple iron.
For electrical and electronics work, a low-power iron, a power rating between 15 and 35 watts, is used. Higher ratings are available, but do not run at higher temperature; instead there is more heat available for making soldered connections to things with large thermal capacity, for example, a metal chassis. Some irons are temperature-controlled, running at a fixed temperature in the same way as a soldering station, with higher power available for joints with large heat capacity. Simple irons run at an uncontrolled temperature determined by thermal equilibrium; when heating something large their temperature drops.
A variation is the Scope soldering iron, common in Australia, which operates from a low-voltage source such as transformer or battery, and heats in seconds when the user pushes the thumb-guard, which then acts as a heat controller.
Cordless iron.
Small irons heated by a battery, or by combustion of a gas such as butane in a small self-contained tank, can be used when electricity is unavailable or cordless operation is required. The operating temperature of these irons is not regulated directly; gas irons may change power by adjusting gas flow. Gas-powered irons may have interchangeable tips including different size soldering tips, hot knife for cutting plastics, miniature blow-torch with a hot flame, and small hot air blower for such applications as shrinking heat shrink tubing.
Temperature-controlled soldering iron.
Simple soldering irons reach a temperature determined by thermal equilibrium, dependent upon power input and cooling by the environment and the materials it comes into contact with. The iron temperature will drop when in contact with a large mass of metal such as a chassis; a small iron will lose too much temperature to solder a large connection. More advanced irons for use in electronics have a mechanism with a temperature sensor and method of temperature control to keep the tip temperature steady; more power is available if a connection is large. Temperature-controlled irons may be free-standing, or may comprise a head with heating element and tip, controlled by a base called a soldering station, with control circuitry and temperature adjustment and sometimes display.
A variety of means are used to control temperature. The simplest of these is a variable power control, much like a light dimmer, which changes the equilibrium temperature of the iron without automatically measuring or regulating the temperature. Another type of system uses a thermostat, often inside the iron's tip, which automatically switches power on and off to the element. A thermal sensor such as a thermocouple may be used in conjunction with circuitry to monitor the temperature of the tip and adjust power delivered to the heating element to maintain a desired temperature. In some models, the firmware for the control circuitry is free software that can be modified by the end-user.
Another approach is to use magnetized soldering tips which lose their magnetic properties at a specific temperature, the Curie point. As long as the tip is magnetic, it closes a switch to supply power to the heating element. When it exceeds the design temperature it opens the contacts, cooling until the temperature drops enough to restore magnetisation. More complex Curie-point irons circulate a high-frequency AC current through the tip, using magnetic physics to direct heating only where the surface of the tip drops below the Curie point.
Soldering station.
A soldering station has a temperature control and consists of an electrical power supply, control circuitry with provision for user adjustment of temperature and display, and a soldering iron or soldering head with a tip temperature sensor. The station will normally have a stand for the hot iron when not in use, and a wet sponge for cleaning. It is most commonly used for soldering electronic components. Other functions may be combined; for example a rework station, mainly for surface-mount components may have a hot air gun, vacuum pickup tool, and a soldering head; a desoldering station will have a desoldering head with vacuum pump for desoldering through-hole components, and a soldering iron head.
Soldering tweezers.
For soldering and desoldering small surface-mount components with two terminals, such as some links, resistors, capacitors, and diodes, soldering tweezers can be used; they can be either free-standing or controlled from a soldering station. The tweezers have two heated tips mounted on arms whose separation can be manually varied by squeezing gently against spring force, like simple tweezers; the tips are applied to the two ends of the component. The main purpose of the soldering tweezers is to melt solder in the correct place; components are usually moved by simple tweezers or vacuum pickup.
Hot knife.
A hot knife is a form of soldering iron equipped with a double-edged blade that is situated on a heating element. These tools can reach temperatures of up to 1,000 degrees Fahrenheit (538 degrees Celsius) allowing for cuts of fabric and foam materials without worry of fraying or beading. Hot knives can be utilized in automotive, marine, and carpeting applications, as well as other industrial and personal uses.
Stands.
A soldering iron stand keeps the iron away from flammable materials, and often also comes with a cellulose sponge and flux pot for cleaning the tip. Some soldering irons for continuous and professional use come as part of a "soldering station," which allows the exact temperature of the tip to be adjusted, kept constant, and sometimes displayed.
Tips.
Most soldering irons for electronics have interchangeable tips, also known as "bits", that vary in size and shape for different types of work. Common tip shapes include: "bevel", "chisel", and "conical". An example of a more specialist tip is spoon or gull wing, which features concavity. See the image for renderings of a few different tip shapes and some of the names given to them.
Pyramid tips with a triangular flat face and chisel tips with a wide flat face are useful for soldering sheet metal. Fine conical or tapered chisel tips are typically used for electronics work. Tips may be straight or have a bend. Concave or wicking tips with a chisel face with a concave well in the flat face to hold a small amount of solder are available. Tip selection depends upon the type of work and access to the joint; soldering of 0.5mm pitch surface-mount ICs, for example, is quite different from soldering a through-hole connection to a large area. A concave tip well is said to help prevent bridging of closely spaced leads; different shapes are recommended to correct bridging that has occurred. Due to patent restrictions not all manufacturers offer concave tips everywhere; in particular there are restrictions in the USA.
Older and very cheap irons typically use a bare copper tip, which is shaped with a file or sandpaper. This dissolves gradually into the solder, suffering pitting and erosion of the shape. Copper tips are sometimes filed when worn down. Iron-plated copper tips have become increasingly popular since the 1980s. Because iron is not readily dissolved by molten solder, the plated tip is more durable than a bare copper one, though it will eventually wear out and need replacing. This is especially important when working at the higher temperatures needed for modern lead-free solders. Solid iron and steel tips are seldom used because they store less heat, conduct it poorly, and rusting can break the heating element.
Iron-plated tips may feature a layer of nickel between the copper core and the iron surface. A nickel-chrome outer plating may be used further back from the very tip, as solder does not stick well to this material: this avoids solder wetting parts of the tip where it would be unwanted.
Some tips have a heater and a thermocouple-based temperature sensor embedded to facilitate a more precise temperature control (TS100 and T12, for instance).
Cleaning.
When the iron tip oxidises and burnt flux accumulates on it, solder no longer wets the tip, impeding heat transfer and making soldering difficult or impossible; tips must be periodically cleaned in use. Such problems happen with all kinds of solder, but are much more severe with the lead-free solders which have become widespread in electronics work, which require higher temperatures than solders containing lead. Exposed iron plating oxidises; if the tip is kept tinned with molten solder oxidation is inhibited. A clean unoxidised tip is tinned by applying a little solder and flux.
A wet small sponge, often supplied with soldering equipment, can be used to wipe the tip. For lead-free solder a slightly more aggressive cleaning, with brass shavings, can be used. Soldering flux will help to remove oxide; the more active the flux the better the cleaning, although acidic flux used on circuit boards that is not carefully cleaned off will cause corrosion. A tip which is cleaned but not retinned is susceptible to oxidation.
Soldering iron tips are made of a copper core plated various metals including iron. The copper is used for heat transfer and the other platings are for durability. Copper is very easily corroded, eating away the tip, particularly in lead-free work; iron is not. Cleaning tips requires the removal of oxide without damaging the iron plating and exposing the copper to rapid corrosion. The use of solder already containing a small amount of copper can slow corrosion of copper tips.
In cases of severe oxidation not removable by gentler methods, abrasion with something hard enough to remove oxide but not so hard as to scratch the iron plating can be used. A brass wire scourer, brush, or wheel on a bench grinder, can be used with care. Sandpaper and other tools may be used but are likely to damage the plating.
Electro-static discharge.
Not all soldering irons are ESD-safe.
Although some manufacturers' mains-powered models are built with the element shaft (and hence the tip) electrically connected to ground via the iron's mains lead, other models' tips may float at arbitrary voltages unless an additional grounding wire is used.
Wattage.
The wattage of the soldering iron is one of the most important factors in a soldering iron. Most of the soldering irons used in the electronics have wattage in the range of 20–60 watts.
Temperature-controlled soldering irons with higher wattage (40 W–60 W) are better than low-wattage irons. It does not mean that temperature-controlled soldering irons with higher wattage apply more heat to the solder joint - it simply means that temperature-controlled soldering irons with higher wattage have more power available to heat the soldering joint if needed.
On the other hand, a soldering iron with low wattage (20 W–30 W) can lose heat faster than it can re-heat itself. This may result in poor solder joints, particularly when soldering bigger solder joints or thick wires.


Supply chain management

In commerce, supply chain management (SCM) deals with a system of procurement (purchasing raw materials/components), operations management (ensuring the production of high-quality products at high speed with good flexibility and low production cost), logistics and marketing channels, so that the raw materials can be converted into a finished product and delivered to the end customer. A more narrow definition of the supply chain management is the "design, planning, execution, control, and monitoring of supply chain activities with the objective of creating net value, building a competitive infrastructure, leveraging worldwide logistics, synchronising supply with demand and measuring performance globally". This can include the movement and storage of raw materials, work-in-process inventory, finished goods, and end to end order fulfilment from the point of origin to the point of consumption. Interconnected, interrelated or interlinked networks, channels and node businesses combine in the provision of products and services required by end customers in a supply chain.
Supply chain management strives for an integrated, multidisciplinary, multimethod approach. Marketing channels play an important role in supply-chain management. Current research in supply-chain management is concerned with topics related to sustainability, volatility, and risk management, among others. An important concept discussed in SCM is supply chain resilience. Some suggest that the "people dimension" of SCM, ethical issues, internal integration, transparency/visibility, and human capital/talent management are topics that have, so far, been underrepresented on the research agenda. SCM is the broad range of activities required to plan, control and execute a product's flow from materials to production to distribution in the most economical way possible. SCM encompasses the integrated planning and execution of processes required to optimize the flow of materials, information and capital in functions that broadly include demand planning, sourcing, production, inventory management and logistics—or storage and transportation.
Although it has the same goals as supply chain engineering, supply chain management is focused on a more traditional management and business based approach, whereas supply chain engineering is focused on a mathematical model based one.
Mission.
Supply chain management, techniques with the aim of coordinating all parts of SC, from supplying raw materials to delivering and/or resumption of products, tries to minimize total costs with respect to existing conflicts among the chain partners. An example of these conflicts is the interrelation between the sale department desiring to have higher inventory levels to fulfill demands and the warehouse for which lower inventories are desired to reduce holding costs.
Origin of the term and definitions.
In 1982, Keith Oliver, a consultant at Booz Allen Hamilton, introduced the term "supply chain management" to the public domain in an interview for the Financial Times. In 1983 WirtschaftsWoche in Germany published for the first time the results of an implemented and so called "Supply Chain Management project", led by Wolfgang Partsch.
In the mid-1990s, the term "supply chain management" gained currency when a flurry of articles and books came out on the subject. Supply chains were originally defined as encompassing all activities associated with the flow and transformation of goods from raw materials through to the end user, as well as the associated information flows. Supply-chain management was then further defined as the integration of supply chain activities through improved supply-chain relationships to achieve a competitive advantage.
In the late 1990s, "supply-chain management" (SCM) rose to prominence, and operations managers began to use it in their titles with increasing regularity.
Other commonly accepted definitions of supply-chain management include:
A supply chain, as opposed to supply-chain management, is a set of organizations directly linked by one or more upstream and downstream flows of products, services, finances, or information from a source to a customer. Supply-chain management is the management of such a chain.
Supply chain visibility, in its origins, was concerned with knowledge of the location/production stage and expected delivery date of incoming products and materials, so that production could be planned, but the development of the term has enabled it to be used to plan orders using knowledge of potential supplies, and to track post-production processes as far as delivery to customers.
Supply-chain-management software includes tools or modules used to execute supply chain transactions, manage supplier relationships, and control associated business processes. The overall goal of the software is to improve supply chain performance by monitoring a company's supply chain network from end-to-end (suppliers, transporters, returns, warehouses, retailers, manufacturers, and customers).
In some cases, a supply chain includes the collection of goods after consumer use for recycling or the reverse logistics processes for returning faulty or unwanted products back to producers up the value chain.
Functions.
Supply-chain management is a cross-functional approach that includes managing the movement of raw materials into an organization, certain aspects of the internal processing of materials into finished goods, and the movement of finished goods out of the organization and toward the end consumer. As organizations strive to focus on core competencies and become more flexible, they reduce ownership of raw materials sources and distribution channels. These functions are increasingly being outsourced to other firms that can perform the activities better or more cost effectively. The effect is to increase the number of organizations involved in satisfying customer demand, while reducing managerial control of daily logistics operations. Less control and more supply-chain partners lead to the creation of the concept of supply-chain management. The purpose of supply-chain management is to improve trust and collaboration among supply-chain partners, thus improving inventory visibility and the velocity of inventory movement. In this section, we have to communicate with all the vendors and suppliers, make some comparisons, and after that, we have to place the order.
Importance.
Organizations increasingly find that they must rely on effective supply chains, or networks, to compete in the global market and networked economy. In Peter Drucker's (1998) new management paradigms, this concept of business relationships extends beyond traditional enterprise boundaries and seeks to organize entire business processes throughout a value chain of multiple companies.
In recent decades, globalization, outsourcing, and information technology have enabled many organizations, such as Dell and Hewlett-Packard, to successfully operate collaborative supply networks in which each specialized business partner focuses on only a few key strategic activities. This inter-organizational supply network can be acknowledged as a new form of organization. However, with the complicated interactions among the players, the network structure fits neither "market" nor "hierarchy" categories. It is not clear what kind of performance impacts different supply-network structures could have on firms, and little is known about the coordination conditions and trade-offs that may exist among the players. From a systems perspective, a complex network structure can be decomposed into individual component firms. Traditionally, companies in a supply network concentrate on the inputs and outputs of the processes, with little concern for the internal management working of other individual players. Therefore, the choice of an internal management control structure is known to impact local firm performance.
In the 21st century, changes in the business environment have contributed to the development of supply-chain networks. First, as an outcome of globalization and the proliferation of multinational companies, joint ventures, strategic alliances, and business partnerships, significant success factors were identified, complementing the earlier "just-in-time", lean manufacturing, and agile manufacturing practices. Second, technological changes, particularly the dramatic fall in communication costs (a significant component of transaction costs), have led to changes in coordination among the members of the supply chain network.
Many researchers have recognized supply network structures as a new organizational form, using terms such as "Keiretsu", "Extended Enterprise", "Virtual Corporation", "Global Production Network", and "Next Generation Manufacturing System". In general, such a structure can be defined as "a group of semi-independent organizations, each with their capabilities, which collaborate in ever-changing constellations to serve one or more markets in order to achieve some business goal specific to that collaboration".
The importance of supply chain management proved crucial in the 2019-2020 fight against the coronavirus (COVID-19) pandemic that swept across the world. During the pandemic period, governments in countries which had in place effective domestic supply chain management had enough medical supplies to support their needs and enough to donate their surplus to front-line health workers in other jurisdictions. The devastating COVID-19 crisis in US has turned many sectors of the local economy upside down, including the country's storied logistics industry. Some organizations were able to quickly develop foreign supply chains in order to import much needed medical supplies.
Supply-chain management is also important for organizational learning. Firms with geographically more extensive supply chains connecting diverse trading cliques tend to become more innovative and productive.
The security-management system for supply chains is described in ISO/IEC 28000 and ISO/IEC 28001 and related standards published jointly by the ISO and the IEC. Supply-Chain Management draws heavily from the areas of operations management, logistics, procurement, and information technology, and strives for an integrated approach.
Supply chain resilience.
An important element of SCM is supply chain resilience, defined as "the capacity of a supply chain to persist, adapt, or transform in the face of change". For a long time, the interpretation of resilience in the sense of engineering resilience (= robustness) prevailed in supply chain management, leading to the notion of "persistence". A popular implementation of this idea is given by measuring the "time-to-survive" and the "time-to-recover" of the supply chain, allowing to identify weak points in the system.
More recently, the interpretations of resilience in the sense of ecological resilience and social–ecological resilience have led to the notions of "adaptation" and "transformation", respectively. A supply chain is thus interpreted as a social-ecological system that – similar to an ecosystem (e.g. forest) – is able to constantly adapt to external environmental conditions and – through the presence of social actors and their ability to foresight – also to transform itself into a fundamentally new system. This leads to a panarchical interpretation of a supply chain, embedding it into a system of systems, allowing to analyze the interactions of the supply chain with systems that operate at other levels (e.g. society, political economy, planet Earth).
For example, these three components of resilience can be discussed for the 2021 Suez Canal obstruction, when a ship blocked the canal for several days. Persistence means to "bounce back"; in our example it is about removing the ship as quickly as possible to allow "normal" operations. Adaptation means to accept that the system has reached a "new normal" state and to act accordingly; here, this can be implemented by redirecting ships around the African cape or use alternative modes of transport. Finally, transformation means to question the assumptions of globalization, outsourcing and linear supply chains and to envision alternatives; in this example this could lead to local and circular supply chains that do not need global transportation routes any longer.
Historical developments.
Six major movements can be observed in the evolution of supply-chain management studies: creation, integration, globalization, specialization phases one and two, and SCM 2.0.
Creation era.
The term "supply chain management" was first coined by Keith Oliver in 1982. However, the concept of a supply chain in management was of great importance long before, in the early 20th century, especially with the creation of the assembly line. The characteristics of this era of supply-chain management include the need for large-scale changes, re-engineering, downsizing driven by cost reduction programs, and widespread attention to Japanese management practices. However, the term became widely adopted after the publication of the seminal book "Introduction to Supply Chain Management" in 1999 by Robert B. Handfield and Ernest L. Nichols, Jr., which published over 25,000 copies and was translated into Japanese, Korean, Chinese, and Russian.
Integration era.
This era of supply-chain-management studies was highlighted with the development of electronic data interchange (EDI) systems in the 1960s and developed through the 1990s by the introduction of enterprise resource planning (ERP) systems. This era has continued to develop into the 21st century with the expansion of Internet-based collaborative systems. This era of supply-chain evolution is characterized by both increasing value-added and reducing costs through integration.
A supply chain can be classified as a stage 1, 2, or 3 network. In stage 1–type supply chain, systems such as production, storage, distribution, and material control are not linked and are independent of each other. In a stage 2 supply chain, these are integrated under one plan, and enterprise resource planning (ERP) is enabled. A stage 3 supply chain is one that achieves vertical integration with upstream suppliers and downstream customers. An example of this kind of supply chain is Tesco.
Globalization era.
It is the third movement of supply-chain-management development, the globalization era, can be characterized by the attention given to global systems of supplier relationships and the expansion of supply chains beyond national boundaries and into other continents. Although the use of global sources in organizations' supply chains can be traced back several decades (e.g., in the oil industry), it was not until the late 1980s that a considerable number of organizations started to integrate global sources into their core business. This era is characterized by the globalization of supply-chain management in organizations with the goal of increasing their competitive advantage, adding value, and reducing costs through global sourcing.
Specialization era (phase I): outsourced manufacturing and distribution.
In the 1990s, companies began to focus on "core competencies" and specialization. They abandoned vertical integration, sold off non-core operations, and outsourced those functions to other companies. This changed management requirements, as the supply chain extended beyond the company walls and management was distributed across specialized supply-chain partnerships.
This transition also refocused the fundamental perspectives of each organization. Original equipment manufacturers (OEMs) became brand owners that required visibility deep into their supply base. They had to control the entire supply chain from above, instead of from within. Contract manufacturers had to manage bills of material with different part-numbering schemes from multiple OEMs and support customer requests for work-in-process visibility and vendor-managed inventory (VMI).
The specialization model creates manufacturing and distribution networks composed of several individual supply chains specific to producers, suppliers, and customers that work together to design, manufacture, distribute, market, sell, and service a product. This set of partners may change according to a given market, region, or channel, resulting in a proliferation of trading partner environments, each with its own unique characteristics and demands.
Specialization era (phase II): supply-chain management as a service.
Specialization within the supply chain began in the 1980s with the inception of transportation brokerages, warehouse management (storage and inventory), and non-asset-based carriers, and has matured beyond transportation and logistics into aspects of supply planning, collaboration, execution, and performance management.
Market forces sometimes demand rapid changes from suppliers, logistics providers, locations, or customers in their role as components of supply-chain networks. This variability has significant effects on supply-chain infrastructure, from the foundation layers of establishing and managing electronic communication between trading partners to more complex requirements such as the configuration of processes and workflows that are essential to the management of the network itself.
Supply-chain specialization enables companies to improve their overall competencies in the same way that outsourced manufacturing and distribution has done; it allows them to focus on their core competencies and assemble networks of specific, best-in-class partners to contribute to the overall value chain itself, thereby increasing overall performance and efficiency. The ability to quickly obtain and deploy this domain-specific supply-chain expertise without developing and maintaining an entirely unique and complex competency in house is a leading reason why supply-chain specialization is gaining popularity.
Outsourced technology hosting for supply-chain solutions debuted in the late 1990s and has taken root primarily in transportation and collaboration categories. This has progressed from the application service provider (ASP) model from roughly 1998 through 2003 to the on-demand model from approximately 2003 through 2006, to the software as a service (SaaS) model currently in focus today.
Supply-chain management 2.0 (SCM 2.0).
Building on globalization and specialization, the term "SCM 2.0" has been coined to describe both changes within supply chains themselves as well as the evolution of processes, methods, and tools to manage them in this new "era". The growing popularity of collaborative platforms is highlighted by the rise of TradeCard's supply-chain-collaboration platform, which connects multiple buyers and suppliers with financial institutions, enabling them to conduct automated supply-chain finance transactions.
Web 2.0 is a trend in the use of the World Wide Web that is meant to increase creativity, information sharing, and collaboration among users. At its core, the common attribute of Web 2.0 is to help navigate the vast information available on the Web in order to find what is being bought. It is the notion of a usable pathway. SCM 2.0 replicates this notion in supply chain operations. It is the pathway to SCM results, a combination of processes, methodologies, tools, and delivery options to guide companies to their results quickly as the complexity and speed of the supply-chain increase due to global competition; rapid price fluctuations; changing oil prices; short product life cycles; expanded specialization; near-, far-, and off-shoring; and talent scarcity. The supply chain management provider not only list the services for users to access, but also other relevant services such as monitor the warehouse and logistics.
Increasing volatility has characterised supply chains since about 2000. Douglass in 2010 referred to an SCM management style known as "extreme supply chain management", which:
Business-process integration.
Successful SCM requires a change from managing individual functions to integrating activities into key supply-chain processes. In an example scenario, a purchasing department places orders as its requirements become known. The marketing department, responding to customer demand, communicates with several distributors and retailers as it attempts to determine ways to satisfy this demand. Information shared between supply-chain partners can only be fully leveraged through business process integration, e.g., using Electronic data interchange.
Supply-chain business-process integration involves collaborative work between buyers and suppliers, joint product development, common systems, and shared information. According to Lambert and Cooper (2000), operating an integrated supply chain requires a continuous information flow. However, in many companies, management has concluded that optimizing product flows cannot be accomplished without implementing a process approach. The key supply-chain processes as stated by Lambert (2004) are:
Much has been written about demand management. Best-in-class companies have similar characteristics, which include the following:
One could suggest other critical supply business processes that combine these processes stated by Lambert, such as:
Integration of suppliers into the new product development process was shown to have a major impact on product target cost, quality, delivery, and market share. Tapping into suppliers as a source of innovation requires an extensive process characterized by development of technology sharing, but also involves managing intellectual property issues.
Theories.
There are gaps in the literature on supply-chain management studies at present. A few authors, such as Halldorsson et al., Ketchen and Hult (2006), and Lavassani et al. (2009), have tried to provide theoretical foundations for different areas related to supply chain by employing organizational theories, which may include the following:
However, the unit of analysis of most of these theories is not the supply chain but rather another system, such as the firm or the supplier-buyer relationship. Among the few exceptions is the relational view, which outlines a theory for considering dyads and networks of firms as a key unit of analysis for explaining superior individual firm performance (Dyer and Singh, 1998).
Organization and governance.
The management of supply chains involve a number of specific challenges regarding the organization of relationships among the different partners along the value chain. Formal and informal governance mechanisms are central elements in the management of supply chain. Particular combinations of governance mechanisms may impact the relational dynamics within the supply chain. The need for interdisciplinarity in SCM research has been pointed out by academics in the field.
Supply chain centroids.
In the study of supply-chain management, the concept of centroids has become a useful economic consideration. In mathematics and physics, a centroid is the arithmetic mean position of all the points in a plane figure. For supply chain management, a centroid is a location with a high proportion of a country's population and a high proportion of its manufacturing, generally within . In the US, two major supply chain centroids have been defined, one near Dayton, Ohio, and a second near Riverside, California.
The centroid near Dayton is particularly important because it is closest to the population center of the US and Canada. Dayton is within 500 miles of 60% of the US population and manufacturing capacity, as well as 60% of Canada's population. The region includes the interchange between I-70 and I-75, one of the busiest in the nation, with 154,000 vehicles passing through per day, of which 30–35% are trucks hauling goods. In addition, the I-75 corridor is home to the busiest north–south rail route east of the Mississippi River.
A supply chain is the network of all the individuals, organizations, resources, activities and technology involved in the creation and sale of a product. A supply chain encompasses everything from the delivery of source materials from the supplier to the manufacturer through to its eventual delivery to the end user. The supply chain segment involved with getting the finished product from the manufacturer to the consumer is known as the distribution channel.
Wal-Mart strategic sourcing approaches.
In 2010, Wal-Mart announced a big change in its sourcing strategy. Initially, Wal-Mart relied on intermediaries in the sourcing process. It bought only 20% of its stock directly, but the rest were bought through the intermediaries. Therefore, the company came to realize that the presence of many intermediaries in the product sourcing was actually increasing the costs in the supply chain. To cut these costs, Wal-Mart decided to do away with intermediaries in the supply chain and started direct sourcing of its goods from the suppliers. Eduardo Castro-Wright, the then Vice President of Wal-Mart, set an ambitious goal of buying 80% of all Wal-Mart goods directly from the suppliers. Walmart started purchasing fruits and vegetables on a global scale, where it interacted directly with the suppliers of these goods. The company later engaged the suppliers of other goods, such as cloth and home electronics appliances, directly and eliminated the importing agents. The purchaser, in this case Wal-Mart, can easily direct the suppliers on how to manufacture certain products so that they can be acceptable to the consumers. Thus, Wal-Mart, through direct sourcing, manages to get the exact product quality as it expects, since it engages the suppliers in the producing of these products, hence quality consistency. Using agents in the sourcing process in most cases lead to inconsistency in the quality of the products, since the agent's source the products from different manufacturers that have varying qualities.
Wal-Mart managed to source directly 80% profit its stock; this has greatly eliminated the intermediaries and cut down the costs between 5-15%, as markups that are introduced by these middlemen in the supply chain are cut. This saves approximately $4–15 billion. This strategy of direct sourcing not only helped Wal-Mart in reducing the costs in the supply chain but also helped in the improvement of supply chain activities through boosting efficiency throughout the entire process. In other words, direct sourcing reduced the time that takes the company to source and stocks the products in its stock. The presence of the intermediaries elongated the time in the process of procurement, which sometimes led to delays in the supply of the commodities in the stores, thus, customers finding empty shelves. Wal-Mart adopted this strategy of sourcing through centralizing the entire process of procurement and sourcing by setting up four global merchandising points for general goods and clothing. The company instructed all the suppliers to bring their products to these central points that are located in different markets. The procurement team assesses the quality brought by the suppliers, buys the goods, and distributes them to various regional markets. The procurement and sourcing at centralized places helped the company to consolidate the suppliers.
The company has established four centralized points, including an office in Mexico City and Canada. Just a mere piloting test on combining the purchase of fresh apples across the United States, Mexico, and Canada led to the savings of about 10%. As a result, the company intended to increase centralization of its procurement in North America for all its fresh fruits and vegetables. Thus, centralization of the procurement process to various points where the suppliers would be meeting with the procurement team is the latest strategy which the company is implementing, and signs show that this strategy is going to cut costs and also improve the efficiency of the procurement process.
Strategic vendor partnerships is another strategy the company is using in the sourcing process. Wal-Mart realized that in order for it to ensure consistency in the quality of the products it offers to the consumers and also maintain a steady supply of goods in its stores at a lower cost, it had to create strategic vendor partnerships with the suppliers. Wal-Mart identified and selected the suppliers who met its demand and at the same time offered it the best prices for the goods. It then made a strategic relationship with these vendors by offering and assuring the long-term and high volume of purchases in exchange for the lowest possible prices. Thus, the company has managed to source its products from same suppliers as bulks, but at lower prices. This enables the company to offer competitive prices for its products in its stores, hence, maintaining a competitive advantage over its competitors whose goods are a more expensive in comparison.
Another sourcing strategy Wal-Mart uses is implementing efficient communication relationships with the vendor networks; this is necessary to improve the material flow. The company has all the contacts with the suppliers whom they communicate regularly and make dates on when the goods would be needed, so that the suppliers get ready to deliver the goods in time. The efficient communication between the company's procurement team and the inventory management team enables the company to source goods and fill its shelves on time, without causing delays and empty shelves. In other words, the company realized that in ensuring a steady flow of the goods into the store, the suppliers have to be informed early enough, so that they can act accordingly to avoid delays in the delivery of goods. Thus, efficient communication is another tool which Wal-Mart is using to make the supply chain be more efficient and to cut costs.
Cross-docking is another strategy that Wal-Mart is using to cut costs in its supply chain. Cross-docking is the process of transferring goods directly from inbound trucks to outbound trucks. When the trucks from the suppliers arrive at the distribution centers, most of the trucks are not offloaded to keep the goods in the distribution centers or warehouses; they are transferred directly to another truck designated to deliver goods to specific retail stores for sale. Cross-docking helps in saving the storage costs. Initially, the company was incurring considerable costs of storing the goods from the suppliers in its warehouses and the distributions centers to await the distribution trucks to the retail stores in various regions.
Tax-efficient supply-chain management.
Tax-efficient supply-chain management is a business model that considers the effect of tax in the design and implementation of supply-chain management. As the consequence of globalization, cross-national businesses pay different tax rates in different countries. Due to these differences, they may legally optimize their supply chain and increase profits based on tax efficiency.
Sustainability and social responsibility in supply chains.
Supply chain networks are integral to an economy, but the health of chains is dependent on the well-being of the environment and society. Supply-chain sustainability is a business issue affecting an organization's supply chain or logistics network, and is frequently quantified by comparison with SECH ratings, which use a triple bottom line incorporating economic, social, and environmental aspects. While SECH ratings are defined as social, ethical, cultural, and health footprints, the more commonly used ESG moniker stands for Environment, Social and Governance. Consumers have become more aware of the environmental impact of their purchases and companies' ratings and, along with non-governmental organizations (NGOs), are setting the agenda, and beginning to push, for transitions to more sustainable approaches such as organically grown foods, anti-sweatshop labor codes, and locally produced goods that support independent and small businesses. Because supply chains may account for over 75% of a company's carbon footprint, many organizations are exploring ways to reduce this and thus improve their profile.
For example, in July 2009, Wal-Mart announced its intentions to create a global sustainability index that would rate products according to the environmental and social impacts of their manufacturing and distribution. The index is intended to create environmental accountability in Wal-Mart's supply chain and to provide motivation and infrastructure for other retail companies to do the same.
It has been reported that companies are increasingly taking environmental performance into account when selecting suppliers. A 2011 survey by the Carbon Trust found that 50% of multinationals expect to select their suppliers based upon carbon performance in the future and 29% of suppliers could lose their places on 'green supply chains' if they do not have adequate performance records on carbon.
In addition to environmental concerns, increased globalization within global supply chains challenges human rights and worker exploitation risks within multinational corporations including forced labor and modern slavery. Textiles, agriculture, and manufacturing are some of the industries with significant labor exploitation risks. There are many different methods governments, corporations, and NGOs use to prevent labor exploitation, including corporate social responsibility, export controls, import bans, and monitoring labor standards.
The US Dodd–Frank Wall Street Reform and Consumer Protection Act, signed into law by President Obama in July 2010, contained a supply chain sustainability provision in the form of the Conflict Minerals law. This law requires SEC-regulated companies to conduct third party audits of their supply chains in order to determine whether any tin, tantalum, tungsten, or gold (together referred to as "conflict minerals") is mined or sourced from the Democratic Republic of the Congo, and create a report (available to the general public and SEC) detailing the due diligence efforts taken and the results of the audit. The chain of suppliers and vendors to these reporting companies will be expected to provide appropriate supporting information.
Incidents like the 2013 Savar building collapse with more than 1,100 victims have led to widespread discussions about corporate social responsibility across global supply chains. Wieland and Handfield (2013) suggest that companies need to audit products and suppliers and that supplier auditing needs to go beyond direct relationships with first-tier suppliers. They also demonstrate that visibility needs to be improved if supply cannot be directly controlled and that smart and electronic technologies play a key role to improve visibility. Finally, they highlight that collaboration with local partners, across the industry and with universities is crucial to successfully managing social responsibility in supply chains.
Circular supply-chain management.
Circular Supply-Chain Management (CSCM) is "the configuration and coordination of the organizational functions marketing, sales, R&D, production, logistics, IT, finance, and customer service within and across business units and organizations to close, slow, intensify, narrow, and dematerialise material and energy loops to minimize resource input into and waste and emission leakage out of the system, improve its operative effectiveness and efficiency and generate competitive advantages". By reducing resource input and waste leakage along the supply chain and configure it to enable the recirculation of resources at different stages of the product or service lifecycle, potential economic and environmental benefits can be achieved. These comprise e.g. a decrease in material and waste management cost and reduced emissions and resource consumption.
Components.
Management components.
SCM components are the third element of the four-square circulation framework. The level of integration and management of a business process link is a function of the number and level of components added to the link. Consequently, adding more management components or increasing the level of each component can increase the level of integration of the business process link.
Literature on business process reengineering, buyer-supplier relationships, and SCM suggests various possible components that should receive managerial attention when managing supply relationships. Lambert and Cooper (2000) identified the following components:
However, a more careful examination of the existing literature leads to a more comprehensive understanding of what should be the key critical supply chain components, or "branches" of the previously identified supply chain business processes—that is, what kind of relationship the components may have that are related to suppliers and customers. Bowersox and Closs (1996) state that the emphasis on cooperation represents the synergism leading to the highest level of joint achievement. A primary-level channel participant is a business that is willing to participate in responsibility for inventory ownership or assume other financial risks, thus including primary level components. A secondary-level participant (specialized) is a business that participates in channel relationships by performing essential services for primary participants, including secondary level components, which support primary participants. Third-level channel participants and components that support primary-level channel participants and are the fundamental branches of secondary-level components may also be included.
Consequently, Lambert and Cooper's framework of supply chain components does not lead to any conclusion about what are the primary- or secondary-level (specialized) supply chain components —that is, which supply chain components should be viewed as primary or secondary, how these components should be structured in order to achieve a more comprehensive supply chain structure, and how to examine the supply chain as an integrative one.
Power in supply chain management.
Andrew Cox, Joe Sanderson and Glyn Watson argue that the power resources of buyers and suppliers should be analyzed in order to understand how a supply chain relationship operates. In some cases, a purchasing firm may exercise more power over its suppliers, in other cases, suppliers may have more power; yet again there will be cases where buyers and suppliers may be interdependent or may have no real power over each other. Cox, Sanderson and Watson have written extensively on the operation of power regimes within a supply chain context. Other studies of power in supply chain relationships have looked at drivers impacting on the potential integration of supply chains. A study by Michael Maloni and W. C. Benton in 1998 looked at whether potential asymmetries in inter-firm power within a supply chain could prevent the implementation of effective supply chain execution. Maloni and Benton note that until their research, "little power research" had been presented in the supply chain literature. Using French and Raven's typology of the sources of power in the context of the automotive industry, they aimed to analyse the effects of distinct power strategies on relationships between buyers and sellers, and upon supply chain performance and satisfaction. Their findings showed that:
They concluded that "prudent use of power" can be beneficial for both the power source and the power target.
Reverse supply chain.
Reverse logistics is the process of managing the return of goods and may be considered as an aspect of "aftermarket customer services". Any time money is taken from a company's warranty reserve or service logistics budget, one can speak of a reverse logistics operation. Reverse logistics also includes the process of managing the return of goods from store, which the returned goods are sent back to warehouse and after that either warehouse scrap the goods or send them back to supplier for replacement depending on the warranty of the merchandise.
Digitizing supply chains.
Consultancies and media expect the performance efficacy of digitizing supply chains to be high. Additive manufacturing and blockchain technology have emerged as the two technologies with some of the highest economic relevance.
Systems and value.
Supply chain systems configure value for those that organize the networks. Value is the additional revenue over and above the costs of building the network. Co-creating value and sharing the benefits appropriately to encourage effective participation is a key challenge for any supply system. Tony Hines defines value as follows: "Ultimately it is the customer who pays the price for service delivered that confirms value and not the producer who simply adds cost until that point".
Global applications.
Global supply chains pose challenges regarding both quantity and value. Supply and value chain trends include:
These trends have many benefits for manufacturers because they make possible larger lot sizes, lower taxes, and better environments (e.g., culture, infrastructure, special tax zones, or sophisticated OEM) for their products. There are many additional challenges when the scope of supply chains is global. This is because with a supply chain of a larger scope, the lead time is much longer, and because there are more issues involved, such as multiple currencies, policies, and laws. The consequent problems include different currencies and valuations in different countries, different tax laws, different trading protocols, vulnerability to natural disasters and cyber threats, and lack of transparency of cost and profit.
Roles and responsibilities.
Supply chain professionals play major roles in the design and management of supply chains. In the design of supply chains, they help determine whether a product or service is provided by the firm itself (insourcing) or by another firm elsewhere (outsourcing). In the management of supply chains, supply chain professionals coordinate production among multiple providers, ensuring that production and transport of goods happen with minimal quality control or inventory problems. One goal of a well-designed and maintained supply chain for a product is to successfully build the product at minimal cost. Such a supply chain could be considered a competitive advantage for a firm.
Beyond design and maintenance of a supply chain itself, supply chain professionals participate in aspects of business that have a bearing on supply chains, such as sales forecasting, quality management, strategy development, customer service, and systems analysis. Production of a good may evolve over time, rendering an existing supply chain design obsolete. Supply chain professionals need to be aware of changes in production and business climate that affect supply chains and create alternative supply chains as the need arises.
In a research project undertaken by Michigan State University's Broad College of Business, with input from 50 participating organizations, the main issues of concern to supply chain managers were identified as capacity/resource availability, talent (recruitment), complexity, threats/challenges (supply chain risks), compliance and cost/purchasing issues. Keeping up with frequent changes in regulation was identified as a particular concern. Complexity within supply chains has also been highlighted in "Supply Chain Digest" and by Gartner as a perennial challenge.
Supply chain consultants may provide expert knowledge in order to assess the productivity of a supply-chain and, ideally, to enhance its productivity. Supply chain consulting involves the transfer of knowledge on how to exploit existing assets through improved coordination and can hence be a source of competitive advantage: the role of the consultant is to help management by adding value to the whole process through the various sectors from the ordering of the raw materials to the final product. In this regard, firms may either build internal teams of consultants to tackle the issue or engage external ones: companies choose between these two approaches taking into consideration various factors.
The use of external consultants is a common practice among companies. The whole consulting process generally involves the analysis of the entire supply-chain process, including the countermeasures or correctives to take to achieve a better overall performance.
Skills and competencies.
Supply chain professionals need to have knowledge of managing supply chain functions such as transportation, warehousing, inventory management, and production planning. In the past, supply chain professionals emphasized logistics skills, such as knowledge of shipping routes, familiarity with warehousing equipment and distribution center locations and footprints, and a solid grasp of freight rates and fuel costs. More recently, supply-chain management extends to logistical support across firms and management of global supply chains. Supply chain professionals need to have an understanding of business continuity basics and strategies, and Tramarico "et al" noted that several processes from other disciplinary theories, including the resource-based view, supply chain design and interorganizational relationships are integral to a mature understanding of supply chain management.
Certification.
Individuals working in supply-chain management can attain professional certification by passing an exam developed by a third party certification organization. The purpose of certification is to guarantee a certain level of expertise in the field. The knowledge needed to pass a certification exam may be gained from several sources. Some knowledge may come from college courses, but most of it is acquired from a mix of on-the-job learning experiences, attending industry events, learning best practices with their peers, and reading books and articles in the field. Certification organizations may provide certification workshops tailored to their exams.
University rankings.
The following North American universities rank high in their master's education in the SCM World University 100 ranking, which was published in 2017 and which is based on the opinions of supply chain managers: Michigan State University, Penn State University, University of Tennessee, Massachusetts Institute of Technology, Arizona State University, University of Texas at Austin and Western Michigan University. In the same ranking, the following European universities rank high: Cranfield School of Management, Vlerick Business School, INSEAD, Cambridge University, Eindhoven University of Technology, London Business School and Copenhagen Business School.
The following universities rank high in the 2016 Eduniversal Best Masters ranking for supply chain and logistics: Massachusetts Institute of Technology, KEDGE Business School, Purdue University, Rotterdam School of Management, Pontificia Universidad Catolica del Peru, Universidade Nova de Lisboa, Vienna University of Economics and Business and Copenhagen Business School.
Organizations.
A number of organizations provide certification in supply chain management, such as the Council of Supply Chain Management Professionals (CSCMP), IIPMR (International Institute for Procurement and Market Research), APICS (the Association for Operations Management), ISCEA (International Supply Chain Education Alliance) and IoSCM (Institute of Supply Chain Management). APICS' certification is called "Certified Supply Chain Professional", or CSCP, and ISCEA's certification is called the "Certified Supply Chain Manager" (CSCM), CISCM (Chartered Institute of Supply Chain Management) awards certificate as "Chartered Supply Chain Management Professional" (CSCMP). Another, the Institute for Supply Management, is developing one called the "Certified Professional in Supply Management" (CPSM) focused on the procurement and sourcing areas of supply-chain management. The Supply Chain Management Association (SCMA) is the main certifying body for Canada with the designations having global reciprocity. The designation Supply Chain Management Professional (SCMP) is the title of the supply chain leadership designation.
Topics addressed by selected professional supply chain certification programmes.
The following table compares topics addressed by selected professional supply chain certification programmes.


Flatbed digital printer

Flatbed digital printers, also known as flatbed printers or flatbed UV printers, are printers characterized by a flat surface upon which a material is placed to be printed on. Flatbed printers are capable of printing on a wide variety of materials such as photographic paper, film, cloth, plastic, pvc, acrylic, glass, ceramic, metal, wood, leather, etc.). Flatbed digital printers usually use UV curable inks made of acrylic monomers that are then exposed to strong UV-light to cure, or polymerize them. This process allows for printing on a wide variety of surfaces such as wood or canvas, carpet, tile, and even glass. The adjustable printing bed makes it possible to print on surfaces ranging in thickness from a sheet of paper often up to as much as several inches. Typically used for commercial applications (retail and event signage), flatbed printing is often a substitute for screen-printing. Since no printing plates or silkscreens must be produced, digital printing technology allows shorter runs of signs to be produced economically. Many of the high-end flatbed printers allow for roll-feed, allowing for unattended printing.
Environmentally, flatbed digital printing is based on a more sustainable system than its commercial predecessor of solvent printing as it produces fewer waste cartridges and less indoor air pollution. The resolution of flatbed printers range from 72 DPI (dots per inch) to about 2400 DPI. One of the advantages of a flatbed printer is its versatility of printable materials although this is limited to only flat materials and occupies a lot of surface area.
"Hybrid" Flatbed Digital Printers.
Although most flatbed printers are limited to printing on flat some are capable of printing of cylindrical objects, such as bottles and cans, using rotary attachments that position the object and rotate it while the printhead applies ink. Flatbed printers have sometimes been used to print on small spherical objects such as ping pong balls, however, the print resolution tends to decrease around the edges of the printed image due to the inkjets firing ink onto an inclined and further away surface.
Flatbed printers can sometimes execute multiple passes on a surface to achieve an 3D embossing effect. This is either done with colored inks or a clear varnish which is used to create glossy finishes or highlights on the print.
"Hybrid" UV printers may also refer to printers capable of printing of a flatbed surface as well as roll-to-roll, which enables the use of flexible substrates stored in rolls.


Cast urethanes

Cast Urethanes are similar to injection molding. During the process of injection molding, a hard tool is created. The hard tool, made of an A side and a B side, forms a void within and that void is injected with plastics ranging in material property, durability, and consistency. Plastic cups, dishware, and toys are most commonly made using the process of injection molding because they are common consumer items that need to be produced on a mass scale, and injection molding (once the hard tool has been created) is designed for mass production.
Casting urethanes is similar in that polyurethanes are injected into a tool. But with cast urethanes, the tool is a soft tool, typically made with a type of silicone mold. The mold is created via a master pattern. Master patterns for cast urethanes can be created with CNC machining (which is a common process for injection molding) but cast urethane master patterns are often created with additive manufacturing (or 3D Printing) and the reasons for this vary.
Creating a cast urethane master pattern is different from the steps involved in creating hard tooling for injection molding. Hard tools for injection molding are going to be subjected to a lot of stress and heat during the injection process. They will see runs of thousands of parts per day. The care that goes into a hard tool involves intense machine programming which costs thousands of dollars alone. The price for hard tooling is balanced by the mass production the tooling brings, which is where cast urethanes begin to differ. Cast urethanes are suited for smaller runs of parts and prototyping. Because the cost for soft tooling is lower, down in the hundreds rather than hundreds of thousands, cast urethanes are excellent resources for creators still testing product design, for one-off products, or for testing market and consumer response to a new product.
Master Patterns.
Cast urethane master patterns can be produced using machining, additive manufacturing—even an already existing product. The master pattern is used to create an A side and a B side for a mold. The pattern is used to form a void within a mold. The mold material is one that easily picks up surface detail (such as silicones) because the mold will be responsible for reflecting the surface of the product.
Applications.
There are many types of cast urethane applications including:
Process.
Cast urethane starts as a liquid that can be dispensed into a mold, post cured in ovens and where required, secondary machining operations can be added. Cast thermoset urethanes have better physical properties than most injection or extruded thermoplastics. Dispensing liquid urethane into open molds or compression tools makes it possible to cast just about any configuration from affordable tooling.
Steps include first printing a master pattern for an accurate silicone mold, which is then encased in liquid silicone. After the mold cures, it is cut into distinct sections and the pattern is removed. The cavity formed is used for casting the end product. The cavity or void is filled with a material, which will cure and be removed from the tool.
Industries.
The types of industries that utilize cast urethane include:


Powertech Technology

Powertech Technology Inc. (PTI  6239. TW) is a Taiwanese semiconductor assembly, packaging and testing company.
In 2010 the company entered a strategic alliance with Japan's Elpida Memory and Taiwan's chip foundry United Microelectronics Corporation to develop advanced semiconductor packaging technology.
The company is purported to be manufacturing Apple Inc.'s Apple S1 chip for their recently announced Apple Watch.