Manufacturers currently wasting material could benefit from cold forming

The figures are quoted in Nederman's 'What a waste' report, available: here While swarf recycling is a potentially powerful way to make savings, precision cold forming, sometimes combined with CNC machining for final part finishing, is an alternative route, says Mark Jennings, engineering director at Dawson Shanahan. Cold forming can be used to process a wide range of metals, including copper, brass and aluminium. Copper is perhaps the most commonly used material and it is here that companies currently machining high volumes of components from tellurium copper (CuTe) rods or bars can derive the greatest benefits, he offers. CuTe is ideal for machining, but techniques such as milling, grinding, turning and drilling all produce large volumes of waste. At current market rates, the scrap value is far lower than the initial stock or raw material price. So for a circular, hollow shaped part, such as might be used in a power generation or distribution unit, with a finished weight of 345 g, you would typically require a solid section of rod weighing 1,071 g, from which around 68% of material is removed as waste. That's over £3.50 of raw material wasted. A value of maybe £2.50 can be recouped from recycling, but why not adopt a process that minimises the need for recycling from the outset, he asks. Here's a typical example of how the cold forming process works. A simple blank, sawn or cut from a round bar or wire, is placed into the cold forming press, where die and a punch tooling is used to extrude the metal under extreme pressure; this is typically between 100 and 200 tonnes, but can be far greater in some systems, up to 2,000 tonnes. The metal is stretched beyond its yield strength, so that it takes on and retains the exact shape of the mould, but without adversely affecting its tensile strength. Unlike conventional machining, where the material removal processes cut across the grain structure of each part, cold forming allows the grain structure of the material to follow the contours of the die or mould. As a result, the strength of the part is maximised along its length, while internal surfaces take on a highly polished finish. Because cold forming has proved increasingly popular, engineers have advanced the process so that now even stainless steel can be cold formed. With growing demands from industry, combined with the need to reduce wastage rates and energy consumption for both economic and environmental reasons, an increasing number of manufacturers are adopting the more efficient and cost-effective method of producing stainless steel components via cold forming, Dawson Shanahan claims. This new development in cold forming looks set to revolutionise the way stainless steel components are manufactured in the future. Precision cold forming is not necessarily the perfect solution in all cases, but, as an engineering process, it deserves greater consideration as part of manufacturers' portfolios of production options. More importantly, at a time of rising raw material costs, precision cold forming can provide a valuable method of protecting profit margins.