As a method of manufacturing precision components, cold forming has dipped under the radar of many engineers. However, the development of cold forming stainless steel looks set to revolutionise the way this material is manufactured, says Mark Jennings, Technical Director at Dawson Shanahan.
Cold forming has long been established as a method for producing simple, high volume components such as fasteners quickly and cost effectively. Increasingly though, this process is being used to produce high precision components from a range of advanced engineered metals. More significantly, a new technique has now been developed by Dawson Shanahan enabling the production of cold formed austenitic and martensitic stainless steels that virtually eliminates galling. This manufacturing breakthrough has offered new opportunities and benefits for component manufacturers operating in a diverse range of sectors, from aerospace and automotive engineering through to medical, electronic and optical instruments. Unlike the traditional energy intensive, time consuming, wasteful or even hazardous methods of shaping metal, cold forming, is a particularly simple process that produces metal components at low ambient temperatures without removing any material.
A typical cold forming press uses coiled wire at room temperature that is then cut to length then using advanced mould and die sets, combined with extremely high levels of applied pressure (in excess of 600 tonnes), and extruded to the desired shape. By working with the material and eliminating the need for trimming and cutting, cold forming can cut waste by up to 80% in comparison with traditional machining processes.
Faster output, lower energy consumption
As cold forming is carried out at ambient temperatures, this high speed process can be completed 15 times faster than more conventional options, significantly saving on production time. As a result, components can be made precisely to order extremely quickly, cutting lead times and the need to store high volumes of spare parts on site. Another, perhaps more obvious, advantage of producing components at ambient temperatures is the significant reduction in energy consumption, helping to reduce costs still further, as well as carbon footprint. Indeed, these benefits can help lower the costs of components by as much as 70% in many instances.
Stronger, smoother parts
Just as importantly, the cold forming process can improve the mechanical properties, with a finished part 18% stronger than that of machined components. Unlike machining where sections are usually cut across the grain structure of the metal, the direction of forming and the geometry of the part is aligned with that of the grain. In addition, finished parts can have complex internal and external geometries, with exceptionally smooth surface finish, so that only minimal secondary processing is needed. This offers the potential for design engineers to specify components to a higher specification and provide that competitive edge in performance.
Stainless steel components
While the technique has long been used with other advanced engineering metals such as copper, aluminium and brass, the inherent strength of stainless steel has been something of a stumbling block for the cold forming process. For engineers today, there is now an alternative to more conventional processes using a safe cold forming technique developed by Dawson Shanahan. This latest innovative development now means that stainless steel, as well as other exotic metals such as titanium, can be cold formed using a specialised metallic lubrication and extrusion coating avoiding the need for hazardous chemical solutions. This unique shell, created by the research and development team at Dawson Shanahan, eliminates the problem of galling, to prevent damage being caused to the components and tooling, which often presents itself in the form of scores or surface imperfections, thus maintaining consistent quality in finished parts. In fact, this new technique has been endorsed by independent laboratory test results, which show that this ground-breaking process retains all the mechanical properties of stainless steel without any detrimental effect on performance.
The advantages of this new process will be of particular benefit to those areas of industry requiring robust, ultra-high precision parts, including laser applications, where cold formed nozzles significantly increase cutting accuracy, or in industrial engines where the parts are used to boost overall reliability, while cutting CO2and particulate emissions. Equally, other stainless steel components made through cold forming, such as diesel injectors for example, are generally more reliable especially when used with biofuels, as these fuels can place greater stresses on conventionally manufactured parts.
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 looking to adopt more efficient and cost effective methods of producing stainless steel components. This new development in cold forming looks set to revolutionise the way stainless steel components are manufactured in the future, by using a more sustainable and responsible approach.