Trade.Information

Company Name: EUROPEAN ALLIANCE FOR SMC

Company Type: Publications

Company Profile

SMC (Sheet Moulding Compound) and BMC (Bulk Moulding Compound) are fibre reinforced composite materials which primarily consist of inorganic ingredients. The organic plastics content is less than 30 per cent by weight: unsaturated polyester resin, a thermosetting resin, which cures by means of a cross-linking reaction. Fibre glass reinforcement guarantee superior mechanical properties. Additional additives like low-profile components, fillers, release agents, catalyst, process additives etc. are used to enhance the performance or processing of the material.

Glass fibres in SMC are chopped into length of 25 or 50 mm. BMC usually contains fibres of 6 or 12 mm length. The amount can vary from 20 to 60 per cent by weight.

As with any material system, be it metallic or plastic, SMC can be formulated to meet specific performance requirements of each material. Such as high tensile strength, high dimensional stability, high heat resistance, excellent electrical performance, class “A” surface, low density, chemical stability, corrosion resistance etc.

SMC/BMC offer many design advantages in part consolidation. Different wall thicknesses, sharp angles, ribs and bosses are feasible. The design flexibility offered by SMC is a good starting point for the consolidation of parts and functions, leading to high performance solutions, at reduced costs.

If you want more information on design, please order our 96-pages brochure “SMC/BMC: Design for Success” from the office of the European Alliance for SMC.

It’s time zu look again at SMC! Recent developments in product properties and processability are opening up new applications. - A brief synopsis of the Automotive Seminar of the SMC-Alliance held in Coventry, U.K. October 2000.

About Company

Bayer AG in Germany was the first to develop a process to produce thermoset polyester sheet molding compound (SMC) during the early 1960s. SMC combined resin, filler, and chopped glass in a doughy, easily handled sheet. The emergence of SMC resulted in the first mass-production process for composites, which offered a wide range of advantages over open-mold hand lay-up and spray-up composite methods.

A key discovery that aided the commercialization of SMC was Uniroyal's patented technology from the early 1950s on the use of magnesium oxide for chemical thickening. That enabled producing a semisolid rather than runny mix of resin, filler, and chopped glass.

Another key discovery was thermoplastic low-profile/low-shrink additives, which were crucial to SMC's future in exterior automotive body panels, where the painted surface finish had to match that of steel. Rohm and Haas launched low-profile SMC in the mid-'60s. That was followed by Union Carbide's modified polyvinyl alcohol additive.

In the late 1960s, several companies began to produce SMC material and compression mold parts. A key early supplier of SMC impregnating lines was Finn & Fram in San Bernadino, Calif.

The auto industry took a strong liking to SMC and it became the predominant market for the material. The first SMC automotive part commercialized is generally considered to be the rear air deflector on Chrysler station wagons in 1969. Another early application was the one-piece grille opening panel (GOP), which debuted on the Pontiac Tempest in 1970, highlighting SMC's ability to consolidate a number of formerly separate metal parts.

In 1970, the Renault 5 bumper was produced in SMC. In 1972, body panels on GM's Chevrolet Corvette were converted from liquid molding to SMC. More penetration in exterior body panels (hoods, doors, tailgates) came with the Pontiac Fiero in 1984 and Renault Espace in 1990, both SMC-intensive vehicles.

SMC and BMC's ability to produce complex shapes gave rise to electrical and business-equipment parts such as Xerox copier frame components. Other non-automotive applications include shower stalls, bathware, fire helmets, and many others.

Today SMC and BMC are looking to deliver even more weight reduction and the trend is toward more structural applications like truck boxes, mid-gates, and seat backs and more sustainable solutions (bio-based resins).

They are now used in a broad variety of industrial sectors thanks to their performances such as:

• High thermal resistance (both Heat Deflection Temperature and Coefficient of Thermal Linear Expansion)
• Smooth surface finish
• High stiffness
• Weight reduction against steelv
• Design freedom
• Corrosion resistance
• Dent resistance