A novel texturing of micro injection moulding tools by applying an amorphous hydrogenated carbon coating

This paper investigates the effect that a novel texturing of replication tools by applying amorphous hydrogenated carbon (aC:H) coating has on the processing conditions in micro injection moulding. Texturing usually increases the surface area of tools leading to higher demoulding forces acting on the component during the ejection stage of the process. As a consequence of this the ejection forces can cause stress marks, deformation, fracture and stretching of the polymer micro features. Therefore, this research studies the effect that a textured aC:H coating with nano scale structures has on the resulting demoulding forces in comparison to an untreated tooling surface. The obtained results demonstrate the beneficial effect of the aC:H surface coating on demoulding forces in replicating nano-scale surface structures. Especially, nano bead-like texturing and nano pillars on the tools' surfaces did not increase the demoulding forces to the levels witnessed on uncoated tooling surfaces, and the aC:H coatings remained a dominant factor in determining the tool performance. The carried out proof of concept study showed that the applied surface texturing method can be considered as an alternative to existing techniques for surface structuring and at the same time to reduce demoulding forces.