INJECTION TRANSFER MOULDING - AN INNOVATIVE BASIS FOR THE PROCESSING OF THERMOPLASTIC MATERIALS

Injection-Transfer-Moulding (ITM) is a combination of the well-known injection moulding and transfer moulding processes where the melt is not directly injected into the cavity in contrast to conventional injection moulding. Instead, the melt dosed in the aggregate is led over to a so called transfer chamber. In a second process step this melt is transferred into the melt cavities of the closed mould by a piston- and cylinder-system. In comparison to the conventional injection moulding, Injection-Transfer-Moulding provides many advantages for both the quality of the part and the flexibility of the manufacturing process. A vital advantage regarding the quality of the part is the low injection pressure necessary to fill the cavity, because of the short gate design. Due to this, it is possible to produce parts with low inner stress, leading to reduced shrinkage and warpage typical for the processing of macromolecular moulding compounds. Furthermore, in many cases the expensive and widely ramified gate system can be reduced, which means less waste and lower costs for secondary finishing. Although these stated advantages are to be generally expected for all plastics, ITM has only been used for the processing of cross-linking plastics so far. Researches at the Institute for Plastics Processing (IKV) made the ITM-Process accessible for the processing of thermoplastic materials by use of a newly developed mould. It was possible to produce high quality parts form different cavities within one cycle.