Mechanical Polishing

Polishing (ESR2, ESR6). ESR 2 – Mechanical Polishing. State-of-the-art
Implementation of the micro forming process requires the realization of dies with high profile accuracy and very fine surfaces (Sa<0.05 μm). Due to the high required material hardness, micro forming dies have been produced in previous investigations mainly by means of micro EDM. 

However, the achieved surface quality is not sufficient and the generation of a heat affected zone on the machined surface is detrimental for the fatigue resistance of the die. Further surface processing is therefore required.

Polishing of micro structured moulds can be done by mechanical polishing using abrasives. While abrasive polishing process using shaped polymer tools with water based diamond slurry yields surface roughness Sa of 4-6 nm and form accuracy of 0.4 μm, its applicability to micro forging dies is hindered by the limited accessibility due to the closed geometry and the high aspect ratio of forging dies. Due to the high aspect ratios and the small dimensions which limit the accessibility to the die surfaces, conventional polishing methods based on the use of fixed or loose abrasives have not been applicable in the micro domain.

Fingerprint concept implementation
An automated polishing process for high profile accuracy though control of the material removal distribution will be developed. A micro polishing set-up including monitoring solutions for micro polishing process fingerprint control will be realized. The product/process μ-polishing fingerprint will establish the correlation between process parameters, material removal, surface roughness and profile accuracy.
Expected progress beyond current state-of-the-art. ESR 2 project aims at filling the gap related to the efficient polishing of micro forging dies by developing a micro mechanical polishing setup for high aspect ratio components and implementation of automatic micro polishing process. The micro mechanical polishing process and fingerprint concept will be implemented and validated for the production of micro forging dies with free form, high aspect ratio, concave micro geometries, targeting surface roughness Sa=20 nm Sa and profile accuracy (max form deviation from specifications) 2 μm.