Compression Moulding is a high-volume production technology, processing Sheet Moulding Compound in large numbers of composite products. SMC is a pre-impregnated composite sheet made by resin, chopped fiberglass, fillers and additives . Compression Moulding requires expensive but very durable steel moulds and is used by Rotec to produce Backing Rings (Loose Flanges) in diameters DN 25 – DN 300 mm.
The SMC is cut into a number of pre-formed layers, assembled into a heated mould and pressed by a hydrolic press. Subsequently, a pressure of 50 to 60 bar is applied in the mould. After curing, the mould is opened and the products are being ejected.
Depending upon the application, SMC may contain various additives such as shrink control agents, UV stabilizers, pigments and curing agents next to the glass reinforcement, the fillers and the resin.
It is important to note that Rotec does not mould holes in any type of flange, but drills the flanges after moulding. This is resulting in much better product properties than products with moulded holes.