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Cold forming
1st Sep 2009
Mark Jennings at Dawson Shanahan describes the process of precision manufacturing metal components known as cold forming, and explains the benefits of this method over more conventional alternatives.

Components made from copper, aluminium and ferrous materials are used throughout a wide range of industrial applications. The quality of these metal parts has a direct impact on the performance and productivity of machinery and equipment, while their cost can have a considerable impact on a company’s bottom line. Therefore, it is important to choose a method of producing these components that is both capable of the level of precision required and also cost effective.

Metal components are typically made using machining techniques or by a combination of forging and machining. Although proven to be effective, these processes can be time consuming, energy inefficient, and wasteful in terms of the quantity of scrap material created from each part. These issues can make it unnecessarily expensive to produce bespoke components.

One increasingly popular alternative to conventional manufacturing techniques is cold forming. This process can be used to produce precision made components, while avoiding many of the problems associated with other production methods. For instance, cold formed parts can be made quickly, with less energy and less scrap. As a result, the costs and lead times can be reduced by up to 70%. The process also has a number of additional benefits, capable of consistently producing stronger components with a better finish.

Although cold forming is now an established process, it is not widely understood by many engineers. In this article, I’ll explain how the process works and what it has to offer, and highlight some of the key factors that design and production engineers need to consider when choosing between a conventional component manufacturing method and cold forming.

What is cold forming?

Cold forming is the process of producing metal components at low, usually ambient, temperatures without removing material. A simple blank, which has been sawn or cropped from a round bar or wire, or a cold headed pre-form is placed within a die and a punch is pressed into the blank. The blank then takes on the form of the punch and the die.

There are a number of types of cold forming, including forward extrusion, backward extrusion and freeflow. The method of cold forming that is most suitable for an application depends on the type of component that is required. Through extrusion, drawing or coining, a blank can be made into a wide range of components, segments and assemblies.

Why cold forming?

There are many advantages to using this process to manufacture metal components. Firstly, significant cost savings can be achieved by reducing waste. With the price of raw materials such as copper at an all time high, and large amounts of metal often required to produce high volumes of components, any reduction in waste can have a considerable effect on operating costs. As cold forming eliminates the need for machining or removing any metal from the blank, there is virtually no waste.

Being carried out at ambient temperatures, cold forming is a much faster process than more conventional options, saving a great deal of production time. As a result, components can be made to order extremely quickly, cutting lead times and the need to store high volumes of spare parts onsite. Production cycle times can be reduced still further on multi-station machinery, which can be particularly beneficial for large production runs.

Both these advantages can help reduce the cost of components by up to 70% in many cases, but, in addition, cold forming can also increase the quality of the finished parts. For example, unlike in forging and machining, the grain structure of the material being elongated is forced to follow the contours of the component. Therefore, the strength of the part is maximised along its length, in much the same way that a piece of wood is stronger “with the grain”.

Furthermore, during cold forming the part undergoes work hardening, improving its machinability and durability. Work hardening dislocates the structure of the metal in a way that prevents further dislocations, therefore strengthening the component. As this increase in strength is comparable to that of heat treating, it can be more cost effective to cold work a less costly and weaker metal than to hot work a more expensive metal, particularly where a precision finish is required.

Producing components using the cold forming process also makes it possible to achieve a superior finish, both internally and on the surface. Accurate internal profiles and complex external profiles are possible, enabling precision parts to be manufactured that can have a significant impact on the performance of the assemblies and machinery in which they are used.

When to use cold forming

Cold forming can be the most efficient and cost effective way to produce a wide range of metal components; however, due to the relatively high setup costs it is particularly suited to large volumes. These costs can be minimised by outsourcing the production process to a specialist component manufacturer that has the facilities already in place to cold form bespoke components.

There is virtually no limit to shape, size and complexity of the metal components that can be produced using cold forming. Simple cold headed parts or highly complex cold formed and finished machined components can be produced for diverse applications in sectors including Aerospace, Automotive, Electronics, Laser, Medical, Packaging, Plasma, Power Distribution, Telecoms and Welding.

Cold forming can be ideal where quality and surface finish consistency are key. This is because cold forming machines have better reproducibility and interchangeability of parts than hot forming machines, allowing components to be precision manufactured to exact specifications time and time again.

In summary

While cold forming remains a relatively little known method of manufacturing metal components, its popularity is increasing due to the time and cost savings that are achievable. With budgets and lead times tighter than ever and modern machinery demanding components that feature sometimes complex profiles and precise dimensions, cold forming can offer an efficient and affordable solution.

For further information, photographs or media interview requests, please contact Sarah Stamp at 4CM on 01296 660080 or via email at sarah.stamp@4cm.co.uk

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This information was written by 4CM
Contact Sarah Stamp. Tel: 01296 660080. Fax: 01296 662274.
Email: sarah.stamp@4cm.co.uk
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