Precision cold forming is emerging as a key technique to reduce metal waste during machining processes in manufacturing and engineering. Cutting costs, reducing waste and improving margins are just some of the benefits this approach has to offer manufacturers. Dawson Shanahan‘s Commercial director, Jeff Kiernan, explains more.
Metals are already expensive materials and their cost continues to rise. Widely used metals like copper and steel are generally seeing steady price increases, despite some market volatility. Copper, for example, reached almost US$7,000 per tonne earlier this year. For manufacturers, the high cost of raw materials is often considered the price of doing business – a factor that cannot be influenced and must simply be endured. However, growing demands from industry to reduce wasted energy and materials for both cost and environmental reasons has prompted manufacturers to explore alternative production techniques that promise far more efficiency.
The high cost of conventional machining
Manufacturing industries focused on high value, precision components and assemblies – such as those found in the automotive, aerospace, medical or power generation sectors – typically require complex parts which must be made from materials that may be challenging. Such components must be produced with extremely high levels of accuracy, using advanced Computer Numerical Control (CNC) machine tools. Sophisticated and extremely accurate, CNC tooling is certainly capable of producing precision components consistently and in large volumes. However, more often than not machining operations are executed using solid billet materials such as blocks of aluminium alloy. Even when using highly skilled operators, conventional machining operations like milling or grinding can therefore be very wasteful. In fact, for many components conventional machining can see more than 80% of the starting material effectively lost in the production process.
This not only consumes far more energy than is desirable, there is also a significant cost in terms of materials consumed. For example, generating large volumes of swarf costs companies dearly. Not only is the metal expensive, it takes considerable time and energy to collect, remove and transport these excess materials for recycling.
Inevitably there are environmental impacts but wasted materials also represent an economic cost that must be borne by the consumer, or the manufacturer, in the form of higher prices or narrower margins. Both affect competitiveness.
Now however, manufacturers are increasingly turning to the technique of precision cold forming which is allied with CNC machining. Although conventional machining is the only solution for many components, where precision cold forming can be deployed as part of the manufacturing process, the potential savings are considerable. In some applications it is possible to reduce the size of the initial metal blank by up to 75%, while scrap volumes can be cut by up to 90%.
Cold forming metals
As the name suggests, the cold forming manufacturing process concerns stamping or pressing a form from a simple blank. With cold forming no material is removed. Instead a piece of solid bar or wire is placed in a die before a punch is pressed into the material to deform it. With sufficient force, even hard materials such as copper, aluminium, brass and stainless steel can be cold formed to create the required shape quickly and without any cutting operations. Long associated with simple, high volume manufacturing such as producing aluminium drinks cans, cold forming is now increasingly being used to produce precision components.
Furthermore, cold forming can offer certain structural benefits. While conventional machining cuts across the metal’s grain structure introducing potential weaknesses, cold forming does not adversely affect the material’s tensile strength. By stretching the metal beyond its yield strength, it takes on the exact shape of the mould, while the grain structure is able to follow the contours of the die. This improves the mechanical characteristics of the material and the strength of the component is maximised.
The result is a cut in production costs, with no associated sacrifice in terms of component quality. Indeed, die-formed surfaces also assume a desirable highly polished finish, as well as improved mechanical characteristics.
Aluminium, Steel and copper alloys are widely deployed materials that are perhaps the most commonly used metals to employ cold forming in the manufacturing process. CuTe is often found in Electrical and Plasma cutting applications which frequently require extensive machining. Cold forming OFHC (Oxygen Free high conductivity copper) can ensure significant component cost savings for the following reasons;
· Cu Te material significantly more expensive the OFHC
· Cold forming can reduce material waste by 70% in certain cases
· Reduced machining time due to the near net shape of the Cold formed pre-form
Another example of using conventional techniques to produce a hollow cylindrical part typically found in an electricity distribution application also see close to 70% of the original solid bar wasted as swarf. For companies machining high volumes of components from CuTe or other metals, the benefits of precision cold forming from specialists like Dawson Shanahan are clear.
In many applications, cold forming is a direct route to a more efficient and environmentally friendly production process. It may not be possible to control the price of valuable raw materials like copper or stainless steel but for manufacturers, precision cold forming is a production technique that can help them to curb costs, by eradicating cutting and machining and avoiding wasting the precious metals they buy.