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Graphic element Research > Growth > Research projects > Products & processes projects > The nuts and bolts of 3d modelling
Graphic element The nuts and bolts of 3d modelling
    09-06-2000
 

The design process for cold-formed metal pieces - such as nuts, bolts, screws and rivets - has largely been one of trial and error. Now, a CRAFT project has developed a new 3D modelling program specifically for use by SME fastener manufacturers. The software, which is based on the finite-element method, allows process designs to be optimised before they are tried out on actual equipment, saving both time and money. Manufacturers can also use it to improve existing products. In addition, it can be used by personnel with no specialist training in finite-element techniques, making it ideal for rapid introduction into existing work procedures.

The metal fastener industry plays a crucial role in supplying many other industries with the nuts, bolts, screws and rivets that, quite literally, hold everything together. These items are manufactured by a process known as cold forming, where the metal is pressed into the desired shape using high pressure and specially designed tools. Until now, designing new tools has largely been a matter of trial and error, even though some tool designers have over 20 years' experience in the industry. Clearly, this is an expensive and time-consuming process.

Developing a third dimension

The impetus for the CRAFT project came from the German SME, Nutap-Schuhl, which manufactures nuts. Tool designers at Nutap-Schuhl were using a two-dimensional design program and they were aware of its limitations. However, all attempts to find an easy-to-use 3D program had failed.

One problem encountered was that all the existing programs had been developed for general purpose use and were difficult to master. In addition, for cold-forming applications it is necessary for the tool surfaces and process conditions to be accurately described as part of the pre-processing system. Usually the tool surface is described using a mesh of triangular elements generated by general-purpose CAD (computer-aided design) systems, but Nutap-Schuhl had discovered the models created in this way were rarely accurate enough for the simulation it was trying to achieve.

Creating a European consortium

Consequently, Nutap-Schuhl contacted the German research organisation, CPM, for assistance in developing a CRAFT project proposal. CPM used its contacts to help Nutap-Schuhl set up the consortium of European SMEs that would enable the development work to take place, with CRAFT support.

In all, five other SMEs participated in the project, including a second German company, Ernst Rosenbach, which specialises in screws, and, from Italy, both Oslat, a major supplier of components to FIAT, and Meci Italia, another screw manufacturer. Two UK SMEs joined: CSW Coldform, a bolt and screw manufacturer, and Henrob - a specialist rivet producer that was involved in the production of the first aluminium car by Audi.

Two associated companies also joined the group. Johnson Precision Tooling from the UK provides specialist equipment to the fastener industry, while Mauer Metallurgische Verfahrenstechnik of Germany specialises in tool coatings, and so provided valuable technical input regarding tool friction.

Dr Gerhard Arfmann of CPM, who co-ordinated the project, says: "Following the initial request, we set about investigating potential 3D software. When we came across a program that had been developed at the UK's University of Birmingham, we knew we had found the basis for what we needed. The CRAFT project's main aims were therefore to develop pre- and post-processing modules to add to this existing software."

  Obtaining multiple benefits

The new software modules, which run on a PC under the Linux operating system, have brought various different benefits to the SMEs. As originally intended, the pre-processing simulation allows the companies to optimise designs on the computer. This not only means less time spent in physical testing, with associated savings in manpower and machinery time, but it means less waste material too. In addition, the software is simple enough for staff to use without an expert background in numerical modelling.

The efficiency of the optimisation process has also allowed the SMEs to extend their product range. Where before it would have been too expensive to consider testing an idea on a speculative basis, the software provides a cost-effective method of trying out some rather more adventurous concepts.

  Starting a profitable dialogue

Another feature is the post-processing aspect. Companies can now look at the production of existing products and check that they are being manufactured efficiently and to the highest possible standards. This is good news for customers who may find they are being offered a better quality product, good news for the companies who may be able to cut their costs, and good news for the environment if less waste is produced.

Finally, the software allows SMEs to demonstrate production concepts to customers, and enter into dialogue with them at an early stage of design. In the past, only large companies have been able to offer such a service. The result is that SMEs can now work in partnership with the companies they supply, influencing the design of products for the benefit of all concerned.

The CRAFT project finished in 1998, and the SMEs are now using the software. They have, however, also been exploring ways to make the results available on a wider scale. To this end, a user group is being set up that will be open to all SME fastener manufacturers, on a subscription basis. The subscription will give the SMEs the right to use the software and also the opportunity have their say in the form of any future development work, for example adapting the modules for other specific applications.

To date a number of companies from both the UK and Germany have expressed an interest in the group.

   
Developing a third dimension
Creating a European consortium
Obtaining multiple benefits
Starting a profitable dialogue
   

Key data

Improving manufacturing processes comes under the Innovative Products, Processes and Organisation key action. This CRAFT project set out to improve the design process for cold-formed metal fasteners, resulting in better and cheaper nuts and bolts.

Project: Special 3D simulation for fasteners industries (BRST-CT96-5064)

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