Strictly-Extrusion

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Multi-injection technologies improve functions and bring added value

Since a few years now, extruded components are standing back in automotive applications. The extrusion process is increasingly replaced by injection technologies: Cooper Standard Automotive specializes in rubber applications; the company decided to widen its production spectrum with thermoplastic 2-component injection parts. The challenge for Cooper (F-35, Vitré) was to produce new parts for the Peugeot 308. Thanks to its well known expertise in the multi-injection field, Billion was chosen by the rubber molder to implement the application.

Vitré, 11.06.2008: The recent launch of the Peugeot 308 may be considered as a milestone in the development of Cooper Standard Automotive. For this project, the manufacturer of window lickers and door seals, based in Vitré (35), has acquired two Billion injection molding machines H1300/2000-750T (7,500 kN). Cooper wants to complete their production tools covering rubber applications, but above all, implement a more competitive alternative to extrusion systems, synonymous of manual clipping and dimensional constraints. An injection molding equipment enables also to integrate more functions; it improves dimensional stability and offers a more flexible part design.

The swing to multi-injection brings two main advantages: combination of several materials, or substitution to another technology. Cooper S.A. has implemented both and thus won twice, by substituting to extruded parts injected ones, molded with 2 materials. On the basis of these new strategic means, Cooper was chosen for the production of components for the new Peugeot 308.

Working as a team

In this migration towards 2-shot injection moulding, Cooper called for two experts:Billion technical team for machines and multi-injection process, and Jean-Pierre Grosfilley SAS for the moulds with indexing plate. With a total of 480 multi-injection tools manufactured so far (rotating tools and moulds with indexing plate), the mould manufacturer Grosfilley, created in 1973, has numerous references in the automotive industry, in particular in the field of sealing parts for car body components. Grosfilley’s speciality is the design of moulds with indexing plate with up to four stations. In general, the mould maker offers the tools with a rheologic simulation.

Cooper, Billion and Grosfilley worked closely together to determine the most suitable overmoulding technology. Technical feasibility and profitability were taken into account. The validation of the complete process with rotating moulds and Sepro robots has been carried out within Billion Technical Center in Bellignat. The start of production at Cooper in Vitré was perfectly optimised.

Cost, Assembly and Recycling advantages

Thanks to the swing from extrusion to injection, clipping items in metal have been replaced by parts in Polypropylene allowing a relevant weight reduction, together with a recycling advantage. The related cost and assembly trumps are undeniable. A better control of part thicknesses allowed also to eliminate metallic shells.

A lot of „Plus points“ compared to extrusion

Parts in PP with elastomer sealings are produced at Cooper with very innovative rotating moulds from Grosfilley. These parts replace the initially extruded ones, which used to be clipsed manually onto a seal; this operation is now cancelled.

According to Cooper, this new manufacturing process of automotive components for the Peugeot 308 offers new design opportunities: the fixing of the parts on car doors and the shape of the door panels are made easier and more flexible. Injection also allows to integrate easily more functions.

Dimensional stability is considerably improved. Extruded parts used to show some variations, whereas the injected parts are much more precise and easily adjustable in dimension.

The surface finish of injected parts is of very good quality, which was not always the case with the extrusion process. In addition, extrusion and injection masterbatches for EPDM are not necessarily equivalent, and colour discrepancies could be noticed between extruded parts, injected parts and other car body components. This problem is solved with the injection process.

Cooper is optimistic

With this new equipment, Cooper Standard Automotive have increased their production capacity, making here substantial savings. The company considers that the 2-component technology introduced for the new Peugeot 308 brings new opportunities: design flexibility for adapting parts to future car body concepts, significant cost and assembly advantages, and easy integration of additional functions.