TPI May 2013

Cold-formed parts have surface finishes that mirror the smooth condition and dimensions of the dies. Not only does this somewhat ‘burnished’ condition often eliminate the need for secondary finishing, it can also invest parts with the capacity to preserve, for example, gases with zero leakage for a number of years. When Dawson Shanahan was commissioned to cold-form an aluminium tube for the purpose of holding nitrogen gas, the customer specified that a minimum pressure must be maintained within the chamber for a period of two years. A rubber seal contacting the chamber inner surface was created to prevent gas loss. It was therefore critical that the chamber surface was free from scratches, eliminating gas leak paths that would lead to a loss of pressure. Although the drawing specification required a 0.2Ra radial surface requirement, the process produced results between 0.04 and 0.08Ra. The remarkable results achieved here by cold forming only demonstrate the powerful potential of this process method to meet the increasingly demanding needs of many applications. With over 60 years’ experience, Dawson Shanahan Ltd is a global specialist in cold forming and machining of high precision, customer-specified copper, aluminium, ferrous and assembled components. The company offers a complete solution, with everything from prototype to production being designed and manufactured in-house, to reduce both manufacturing lead time and costs. The company’s products meet the demands of a wide range of sectors including aerospace, automotive, electronics, laser, medical, packaging, plasma, power distribution, telecoms and welding.

Cold forming offers a strong, economical alternative when the complexity offered by hot forming is unnecessary

This is because, during machining, bar stock grain is interrupted, while cold-headed parts have a grain that follows the configuration of the part. Cold forming therefore offers improved mechanical properties with a greater strength-to- weight ratio. Cold forming is also allowing a greater number of parts to be formed as single components, rather than a series of separate ones. The potential to produce components of net, or near net, shape has had a great impact on efficiency and economy, as it reduces the need for many secondary operations. The influence of cold forming continues as research and development into the process shifts the balance away from ‘experience-based’ development towards computer-aided research, ushering in a more analytical approach. The potential to engineer high precision components by cold forming aluminium is illustrated by a recent Dawson Shanahan project that required a unique finish.

Cold forming can provide a faster process option than die-casting or machining from solid aluminium

Dawson Shanahan Ltd – UK info@dawson-shanahan.co.uk www.dawson-shanahan.co.uk

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Tube Products International May 2013

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