SMC is a sheet molding material which is made of resin paste impregnated with chopped glass fiber roving or glass fiber felt and coated with polyethylene or polypropylene film on both sides.
Types of SMC
BMC (bulk molding compound) is a kind of block molding plastic. It has low fiber content, short fiber length, large filler content and lower strength than SMC. It is suitable for manufacturing small products;
TMC (thick molding compound), thick sheet molding plastic, the thickness of SMC is generally 6.3mm, and the thickness of TMC can reach 50.8mm. Reduce the amount of polyethylene film, reduce the cost, more widely used;
Structure SMC can be divided into smc-r (fiber irregular distribution), smc-c (continuous fiber unidirectional distribution), smc-d (discontinuous fiber directional distribution), smc-c / R and smc-d / R according to the fiber morphology and distribution. The fiber content is between 30% and 70%, and the resin adopts high reactive isophthalic acid polyester resin.
High strength SMC is the first high strength molding compound developed by PPG company in the United States.
HMC is a kind of sheet molding plastic with little or no filler, the content of chopped fiber is 60% - 80%, the orientation distribution of glass fiber, and the content of resin is less than 35%. It has excellent fluidity and molding surface, and its product strength is three times of that of ordinary SMC products.
XMC is a kind of sheet molding plastics which contains 70% - 80% directional continuous glass fiber, 20% - 30% polyester resin and some or no fillers. The glass fiber is arranged at a certain angle, and the standard roving angle is 82 °. The strength of its products in a certain direction is 4 times of that of steel, and its quality is 1 / 2 of that of steel.
Ls-smc (low shrinkage SMC) is manufactured by using low shrinkage resin or adding thermoplastic low shrinkage additive. The shrinkage of the finished product tends to zero. It is suitable for manufacturing products with high dimensional accuracy and high surface finish
Itp-smc (interpenetrating thickening process SMC) has high rigidity, impact resistance and dimensional stability.
SMC molding plastic process flow chart
SMC unit
SMC resin paste formula