Influence of the injection velocity profile on the properties of injection moulded parts

Abstract

An important machine setting parameter of the injection moulding process is the injection velocity, which influences the local process parameters in the mould cavity and as a result the final part properties. In order to avoid surface defects by too low or too high melt front velocities along the flow path, profiling of the injection velocity can be necessary. Therefore, in previous work, a methodical approach has been developed, which calculates an injection velocity profile that can be set directly at the injection moulding machine, in order to gain a constant melt front velocity along the flow path. Using the existing approach, two different part geometries are injection moulded with an injection velocity profile from two different materials. The resulting microscopic and macroscopic part properties are evaluated and compared with the samples produced at a constant injection velocity. By keeping the melt front velocity constant, the surface quality can be specifically influenced, while other properties are hardly affected by profiling the injection velocity.