In this study an experimental methodology to study surface wear of injection moulds on a full scale polymer injection moulding machine is developed. A comparative study of four different tool materials for mould cavities is carried out in situ. The polymer injection conditions (geometry cavities, machine settings, polymer) are chosen in order to accelerate the degradation of the mould cavity surface. The reinforced polycarbonate resin Lexan 341R-739, containing 40% of weight of short glass fibres, well known for their abrasive character, was injected with jetting and normal injection conditions. Jetting conditions implies high pressure and velocity of the injected resin. The die wear is discussed in relation to the polymer flow conditions and the die materials.

Injection-moulded thick plates were produced using a short glass fibre-reinforced thermoplastic. We studied the effect of processing parameters on voids rate inside the parts. Voids rate was measured using an optical microscope. Mass and density measurements were compared with each other in order to define the most relevant method for voids detection. The hydraulic holding pressure level is the most relevant process parameter. As this parameter increases, we found a twodomain relationship between density and mass. In the first domain, injection-moulded parts include voids, and mass is proportional to density, with the volume of the part as slope. In the second domain, the slope is different from this volume, parts are void free, but residual stresses appear. We defined an optimum hydraulic holding pressure level, leading to voids free parts. This optimum cannot be detected using mass measurements, but it is easily detectable using density measurements.