Licence plate panels and trunk lids were among the first applications for SMC/BMC in the automotive industry. In the meantime, the technology has been further refined and the number of applications has grown. At a technical conference entitled “SMC/BMC – New Challenges in Automotive”, organised by the European Alliance for SMC (www.smc-alliance.com) and held in Bremen / Germany, speakers presented a number of examples of the latest developments.

Manufacture of SMC semi-finished products (Ill.: Saint Gobain)

Dr. Alexander Kruse from Daimler Chrysler´s Bremen plant told the 140 delegates that the “benefits of SMC/BMC lie in their additional design scope, reduced weight and improved corrosion protection.” In mid-2004, the first SMC/ BMC parts are scheduled to start coming off Daimler´s production line in Bremen, and Kruse said a strategy group has been set up with the name “Plastics in the Outer Skin”. He predicted a period of “rapid growth” for SMC/BMC materials. Nearly all car manufacturers use SMC/BMC for some application or other, ranging from rear spoilers and tailgates to fenders and complete front ends. So far, however, the latter have only been manufactured in small runs by US manufacturers. Other less frequent applications involve parts that do not belong to the outer skin, such as spare wheel trays (Renault “Megane”, Peugeot “607”) and valve covers, injection moulded from long fibre-reinforced TMC (Dodge, GM).

Per mould, some 120,000-130,000 parts can be compression or injection moulded explained Michael Sommer (BYK-Chemie). He said that since steel is more economical for larger production runs, SMC/BMC mouldings should, wherever possible, replace several steel parts at once. A good example of this is the Ford “Transit” where, in the front end, one SMC part replaces 19 steel components.

The antenna module on the Volvo “XC90” is positioned under a plastic cover at the
rear of the roof (Ill.: Bayer MaterialScience)

The most recent application for SMC/BMC is the integration of antenna units into plastic components, which would not be possible with metal because of its screening effect. Up to now, the antennas were distributed throughout the vehicle, with complicated configurations needed to ensure good reception. In the Volvo “XC 90”, all the antennas and receivers – for radio, TV and the GPS system, for example – are accommodated in a single module. The antennas are integrated into a film that forms part of a hybrid plastic/metal component. This design also obviates the need for troublesome cables. A similar solution is possible with the use of SMC.

The reason why SMC/BMC parts have only now begun to make their mark in car production lies essentially in problems arising with the manufacture of the semi-finished products, the coating process and the final assembly. Until now, SMC/BMC composites have been used almost exclusively for outer skin parts in which Class A finishes are specified. “People need to change their way of thinking and consider using SMC/BMC for structural parts, too,” said Hans Haug of Karmann.

Book Service: Conference Handbook “SMC/BMC – New Challenges in Automotive”, eight presentations, with CD-ROM, including numerous illustrations: EUR 69.00 + VAT, PIE-No. B 46355.