Abstract: Aiming at achieving low density SMC, raw material selection, formulation design, process control of SMC were studied by molding process. Firstly, the density, the radiance and flexural strength properties of SMC product were investigated by using different hollow glass spheres (HGS). It was found that VS5500 and H40 were appropriate packing for low density SMC. Since the design density and real density of the two products are similar, the mechanical property has small losses. Secondly, the glass fiber content and resin type on mechanical property were also investigated. The survey results indicated that the density of SMC product should be larger than 1.2 g/cm³. Otherwise, the breakage rate of hollow glass spheres will be increased. At the same time, EK100 is a good choice because of effective control of the resin paste viscosity. In addition, the product mechanical properties were enhanced from 148 MPa to 172 MPa by increasing glass fiber from 25% to 30%. If the glass fiber continue to increase, flexural strength would reduce to 140 MPa. The appearance and mechanical properties by using three different types of resin were also studied. It was found that the appearance of product is the best by using P18-03 resin, and flexural strength is 172 MPa, which can satisfy the requirement of automotive mechanical. Lastly, the relationship between parts density and treatment on hollow glass spheres was estimated. The results showed that drying glass spheres can effectively reduce the water content in the resin paste, ensuring SMC compound with an appropriate window for molding.

Key words: light-weight of automobile, low density SMC, hollow glass spheres