Materials • Processes • Finishes
4 Jon Severn investigates how precision cold forming has the potential to help manufacturers reduce component costs by up to 70 per cent, shorten lead times and, at the same time, improve mechanical properties and surface finish.
4 Jon Severn enquête sur comment le formage de précision à froid permet aux fabricants d’économiser jusqu’à 70% sur leurs frais de composants, de réduire leurs délais de réalisation tout en optimisant leurs propriétés mécaniques et leur finition de surface.
4 Jon Severn ist der Frage nachgegangen, wie die Präzisionskaltumformung ein Einsparpotential von bis zu 70 Prozent bei den Materialkosten der Hersteller realisieren, Lieferzeiten verkürzen und gleichzeitig die mechanischen Eigenschaften und die Oberflächengüte verbessern kann.
Precision cold forming receives a warm reception
C
ompetition from developing economies such as China, India and Brazil presents a threat to European manufacturers, especially as these countries are now capable
of producing high-quality goods. At the same time, raw material prices have increased significantly in recent years, largely due to the demand from China, yet the global economy makes it very difficult for manufacturers to increase their prices to compensate for higher costs. Two engineering materials that have been the subject of sharp price rises are copper and stainless steel, though the latter appears to have peaked and returned to levels more commensurate with the long-term trend. Copper is used extensively in many different
sectors, from power generation and distribution, through to automotive and electronics. The recent rises in copper prices - and predicted long-term rises - are a significant problem for manufacturers using this metal, and the situation could well be compounded by copper inventories falling to their lowest levels on record. Users are therefore seeking ways to remain productive, competitive and profitable in such difficult times (Fig. 1). Cold forming can deliver significant benefits
to manufacturers using high volumes of copper for precision parts, especially when mill-supplied
tellurium copper (CuTe) rods or bars are specified. Although this alloy machines well, the processes that have traditionally been used to create finished parts - such as turning, milling, drilling and grinding - usually generate substantial amounts of waste material with a scrap value substantially lower than the stock price.
Less waste
For example, machining a typical 36 g tellurium copper nozzle for plasma or laser welding applications generates 177 g of swarf, representing over 80 per cent of the total starting weight. Depending on the prevailing copper price, this could easily equate to well over €1 of waste per component. In contrast, precision cold forming produces
minimal waste, often uses oxygen-free copper, and can therefore be much more commercially viable than machining tellurium copper. Indeed, oxygen-free copper is readily available, so prices are extremely competitive - and generally far lower than that of tellurium copper. Moreover, in many applications the components precision cold formed from oxygen-free copper can be superior to machined components thanks to the metal’s better electrical and thermal properties. Cold formed components can also benefit from superior mechanical characteristics and a better surface finish. Other valued characteristics of copper, such as its antimicrobial properties and the ease with which it can be recycled, remain unaffected by cold forming.
New process
Dawson Shanahan is a specialist in precision cold forming parts from copper, aluminium and ferrous metals. Recently the company reported that it developed an innovative production process that could revolutionise the way stainless steel parts are made. The process enables high-precision stainless steel parts to be produced quickly, efficiently and with minimal waste. Until the development of this new process,
Fig. 1. Precision cold forming components can be considerably more cost- effective than machining from solid, especially with relatively expensive metals such as copper.
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cold forming was generally restricted to ductile materials such as aluminium, copper and brasses. Cold forming tougher and more brittle alloys such as stainless steel has only been achieved using extremely expensive and often hazardous and/or environmentally unfriendly techniques. The Dawson Shanahan process for cold forming
stainless steel features specialised lubrication and protective coatings, together with enhancements in
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