Targeted Solidification through Self-optimising, Highly Segmented Mould Temperature Control in Injection Moulding

Abstract

The precision of manufactured parts is one of the most important quality criteria in mass production processes. While for mechanical machining processes high-precision parts can be achieved by using CNC techniques and high-precision machining, melt-based production processes still have large precision drawbacks, which can only be compensated by time-consuming mould trial iterations or post-processing. The following article discusses a new approach to incorporating a segmented temperature control system in an injection mould, leading to a processing technique which is capable of local adjustment of the part temperature. This segmented local temperature control, which is based on appropriate heating and cooling techniques and a novel control approach, is designed to have a positive effect on the solidification of the melt and shrinkage of the plastics part in order to achieve minimal part warpage. This process control is extremely demanding in terms of temperature control techniques, process measurements and control strategies, which are discussed below. Firstly, temperature control techniques that are able to deliver high performance and allow the most dynamic control of the part's surface temperature are discussed and evaluated. To control this process effectively, various sensors are analysed which are capable of measuring real part temperatures within the process runtime. Finally, the requirements for a control concept that allows efficient control of mould temperature are discussed, taking account of high dead times.