For making parts in larger production series (500 to 100,000 parts per year) material solutions based on SMC (Sheet Molding Compound) and BMC (Bulk Molding Compound) are frequently used, as they can be easily molded into unique shapes and have a capability to be made with high dimensional accuracy. Also, they bring light weight compared to steel, aluminum, and stone, can resist heat (thermal insulation, dimensional stability), and provide great strength, stiffness, mechanical integrity, better than what is possible with thermoplastics.
SMC and BMC are mixtures of resin, fillers and reinforcement, processed in heated mold to form a cured component. SMC is a sheet consisting of uncured resin reinforced with glass fibers, which is laid into the mold and compression molded. BMC is a bulk mixture of uncured resin reinforced with glass fibers, which is injected into the mold.
SMC has longer fiber length than BMC and a higher fiber content, resulting in greater flexural strength and tensile strength. SMC is used for larger flat parts, components with higher structural requirements, and parts that need good cosmetics. Parts where SMC is used include automotive body panels, building façade panels, deck lids, and electrical cabinetry.
Because of the shorter fiber length and lower fiber content, BMC can be injection molded and fill finer cavities and thinner parts. The higher filler content results in a smoother surface. Application examples include car headlamp reflectors, appliance components (iron heat shields, coffee machine parts, fuse switches, oven handles), and car engine throttle bodies.
The Palapreg® resins supplied by AOC have set the industry standard in SMC and BMC already for many years. Used by our customers as key ingredients in SMC and BMC formulations, they find their way in many applications in Transportation, Electrical, and Building & Infrastructure.
Depending on the required mechanical properties, density, surface quality, solutions are available in Vinyl Ester, Orthophthalic and Maleic chemistries.
AOC is the leading supplier of high quality Low Profile Additive (LPA) systems, which provide the right solutions for achieving superior surface smoothness, low shrinkage, and full part pigment-ability. Being at the forefront of technology development in SMC and BMC, AOC provides innovative material solutions like Styrene-free resins for reduced odor and smell, special resin systems for low interior emissions, low density formulations for reduced part weight, and resins that bring great strength and stiffness in combination with carbon fibers.
AOC has two R&D centers supporting customers in SMC applications, one based in Zwolle (Netherlands) and one in Nanjing (China), with state-of-the-art equipment and support facilities.
Please read Blogs on SMC Design, Carbon composites, news on SMC BMC Design Award, and case study Mercedes Roadster (describing close collaboration Daimler, Menzolit and AOC).