SMC Mould process is the most important process technology for fibre reinforced polymers today. It is characterized by the flow behaviour of the semifinished flat SMC-sheet under heat and pressure in the pressmould - a kind of press-flow-forming technique. The SMC-sheet is built up continously from short fibre (20 -50 mm) or endless-fibremats impregnated with a filled resin system. The process principle is shown in fig. 1 (7.2.1 Buch 3) After finishing the "SMC-sheet" it will be stored for several days to reach the adequate consistancy.
According to the shape of the structure, or the part, the SMC-sheet will be cut roughly to the geometrical dimensions (regarding the weight of the finished part - not the volume!). Positioing the sheet in a heated mould (constant temperature) the uncured matrix system will drop its viscosity. Under the pressure of the press the system will flow to fill the complete mould (near netshape). In parallel the curing process is starting and after a short time the cured part will be demoulded and trimmed for the final shape. The complete process is shown schematically in fig. 2. As to be seen the processtechnique is automized to a rather high degree today and can be used for massproduction (automotive industry).
For seriesproduction the moulds are metal (mainly steel) dies which are heated with steam to temperatures around 120° C to reduce the curing time.
Adding polymerparticles which are expanding during the heating process the shrinkage of the matrix nearly can be equalized - called "low profile"-systems - for flat and dimensional stable structures.
