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Case study: Gas-assist molding

Making elastomer headlamp seals with gas-assist


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April 1, 2002 by Canadian Plastics


An insight into how elastomers and gas assist can be combined to make sealing systems for automotive applications is provided by Karl Berdan, technical sales representative, Bauer Plastics Technology in his guidelines for gas assisted molding. Current headlamp seals are injection molded in EPDM and PVC with flexible sealing lips, which are expensive to produce and do not provide an optimum seal against the elements, Berdan writes. With PVC use being phased out in some markets, the window has opened for newer engineered TPEs to be used in some of these automotive applications. A combined TPE/gas-assist system can provide a tighter seal and eliminate snap-on attachments molded into the headlamp housings.

In one particular project a prototype mold was built from aluminum and used in conjunction with gas-assisted injection molding to make seals from elastomers. In the past, there was a concern that a high viscosity elastomer would clog the nitrogen injectors, but with today’s technology the injectors are self cleaning.

Bauer Plastics Technology 705-526-8650