OPTIMOULD

The idea for the Optimould project arose from the desire to improve the productivity of companies by using micro-nano texture on plastic injection moulds using laser and EDM technologies.

Optimould identified the optimum surface energy required and the combination of mould surface texture and the appropriate polymer. 

In the context of the Optimould project, the effect of Laser and EDM texturing on the hardness of the treated steel and on the release of plastic parts was studied. Several test moulds of various geometries were made and inserts of different textures were produced. Systematic demoulding tests were carried out in which the ejection force was characterised as a function of the polymer and as a function of the roughness of the textures.

The attached picture shows a result for the case of a "gearwheel" geometry. A reference insert was produced using wire EDM with a roughness Ra<0.1 um. Inserts with a higher roughness between Ra=0.5 um and Ra=2.0 were produced by sinker EDM. 
The results for five polymers showed that the optimum roughness for release from the mould is a compromise between a very smooth surface that promotes adhesion and a very rough surface that promotes friction.

Similar tests were carried out with other geometries which also allowed the potential of laser treatments to be compared with EDM treatments.

The results of this project were validated in a production environment.