Compression transfer moulding process (CTM)

The compression transfer moulding process (CTM) is an injection press process with which the rubber mixture placed in the upper part of a vulcanization mould is injected (transferred) when applying the press through channels in the mould cavity. CTM vulcanization moulds are made up of three parts (upper, middle, lower part).

Compared to Compression moulding (CM) or press processes the vulcanization time is shortened since the rubber mixture is additionally heated up through the occuring frictional heat from the injection in the cavities. The transfer unit found in the upper part of the mould can also be filled through the injection aggregate of an injection moulding machine. One then speaks of Injection transfer moulding process (ITM).

Transfer moulding processes are especially suitable for the production of small rubber moulded parts in moulds with many cavities. A disadvantage of the CTM or ITM process is the high filling amount of unvulcanized elastomer material in the transfer unit. Through the use of transfer moulding cold runners the waste amount can however be substantially reduced.