Cavity Pressure Behaviour in Micro Injection Moulding

Abstract

Process monitoring of micro injection moulding (µIM) is of crucial importance to analyse the effect of different parameter settings on the process and to assess its quality. Quality factors related to cavity pressure can provide useful information directly connected with the dynamics of the process as well as with the filling of the cavity by the polymer melt. In this paper, two parameters derived from cavity pressure data collected by a pressure sensor have been defined: pressure increase rate during filling and the integral of pressure over time (i.e. pressure work). The influence of four µIM parameters (melt temperature, mould temperature, injection speed, and packing pressure) on the two pressure-related outputs has been investigated by moulding a micro fluidic component on three different polymers (PP, ABS, PC) using the design of experiment approach. Similar trends such as the effects of a higher injection speed in decreasing the pressure work and of a lower mould temperature in decreasing pressure rate have been found for all three materials.