Sheet Molding Compound

Posted on June 16th, 2014 by admin

Sheet molding compound (SMC) is both a process and reinforced composite material. The composite is a “ready to mold” glass or carbon fiber reinforced polyester material primarily used in compression molding. The sheet is provided in rolls weighing up to 1000 kg. The SMC sheets are manufactured by dispersing long strands of chopped glass fibers or carbon fibers on a bath of polyester resin, vinylester resin or epoxy resin.

SMC materials are thermosets and contain glass or carbon reinforcement levels between 10 and 60 %. The longer fibers in SMC result in better strength properties than standard bulk molding compound (BMC) products. Typical applications include demanding electrical applications, corrosion resistant needs, structural components at low cost, automotive, and transit. SMC delivers high surface quality. SMC is used for larger parts where higher mechanical strength is needed.

Sintex – Wausaukee Composites has the expertise in Sheet Molding Compound (SMC) which allows us to produce cost-effective solutions for our OEM customers. SWC specializes in SMC parts for:

Fan shrouds
Fenders
Air Baffles
Generator Enclosures

The SMC process allows high molded-in detail, including ribs, bosses, inserts, and minimal thickness variations. SMC parts display excellent temperature and fire resistance. Piece parts are cost effective solutions for structural and non-structural applications.

Manufacture of sheet molding compounds is a continuous in-line process. Sheet molding compounds can be molded into complex shapes. Superior mechanical properties and surface appearance, plus excellent electrical insulation make this thermoset material ideal for OEM Class A body panels, high-strength electrical parts, business equipment cabinets, personal watercraft, and various structural components.

Why SMC Glass Reinforced Composites?

Durability

SMC parts offer superior mechanical and surface appearance. SMC benefits offers very high volume production ability, excellent part reproducibility, and is cost effective due to low labor requirements and reduced scrap production. SMC structures made of composites have a long life and need little maintenance. Composites are corrosion resistant with matrices and binders that prevent environmental attack on fibers and increase resistance to corrosive environments.

Performance

Composites combine high strength and low weight, are non-corrosive and have thermal and electrical insulation properties. Composites can be machined like wood using diamond-tool equipment.

Excellent Cosmetic Finish

Composites can be designed with a high level of surface detail. Parts can be offered in various thickness either coated with high gloss gel coats or with a paintable surface.

General Design Guidelines

Minimum Radius1 mm (0.0625 in)
Minimum Draft4 degrees
Minimum Thickness3 mm (0.125 in)
Maximum Thickness13 mm (0.500 in)
Typical Reinforcement Loading10 – 60 %
Density (50% glass)1938 kg/m3 (.070 lb./in3)
Die Lock (Reverse Draft)Yes

Selection Guidelines

Moderate to high production volumes 5,000 – 100,000 parts/year
Consistent controlled thickness & cross sectional tolerances of +/- .2mm
Large structurally reinforced parts requiring two-sided finish
Molded in labels, raised numbers, inserts and bosses possible
Sintex - Wausaukee Composites

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