Preliminary study on surface influence on injection moulding process at micrometer scale

Injection moulding of micro-featured plastic parts is becoming more and more important for applications of micro system technologies in different fields (IT, healthcare, medicine) due to its capacity to produce low-cost and high repeatable micro polymeric parts. However, approaching the micro world, different issues related to the process should be addressed, especially as the depth of the mould cavity becomes very thin. In particular, the characteristics of mould surface could affect not only the surface quality of micro components, but also the filling of injected parts. This work aims to identify the effect of the superficial texture on the filling capability of thin cavity in micro injection moulding process, and to evaluate the influence when the texture is obtained by different machining processes. The results of the experiments, carried out using a polymeric material, are discussed in the paper and show that, when the surface has an isotropic texture, the filling is proportional to the increase of the surface roughness, whereas an oriented direction of the texture longitudinal to the flow front favours the injection process.