The Injection Transfer Moulding Process in Comparison
to the Multi-Cavity Injection Moulding
Walter Michaeli, Martin Koch and
Tobias Pfefferkorn*
Pontstraße 49, 52062
Abstract
Injection
transfer moulding (ITM) is a combination of the well known injection moulding
and transfer moulding processes. By ITM the melt is not injected into the
cavities directly, but first is led into a so called transfer chamber. In a
second process step the melt is transferred into the mould cavities by a
piston / cylinder system.
Although
the ITM process provides many advantages compared to conventional injection
moulding, ITM has until now only been used for processing crosslinkable
plastics. Research work at the Institute of Plastics Processing (IKV) made the
ITM process accessible for the processing of thermoplastic materials by use of
a newly developed mould.
A
main advantage of the new technology is the low injection pressure necessary to
fill all cavities uniformly due to the short flow paths. Plastics processed by
ITM are exposed to lower shear stresses. Herewith the ITM process allows the
production of parts with lower inner stresses and reduced shrinkage and warpage.
This
paper discusses the mould technology, the course of the ITM process as well as
the resulting part qualities. In addition, a first comparison of the ITM
process to conventional moulds with hot runner systems is given.