Improvement on precision grinding process

In the case of the precision grinding processes, the issues to be solved during the project were related to the optical component manufacturing processes from Kaleido technology. As in the case of the micromilling process, the most important deviations on part quality are related to the appearance of tool wear and its effect on the generated part geometry and surface quality, together with the generation of process instabilities. The first development linked to the precision grinding process has been oriented to the accurate on-machine measurement of the actual geometry for the grinding tools. Using a non-contact on-machine laser device from BLUM-Novotest, the University of Bremen has developed an automatic method for the accurate characterisation of the grinding tools. Validated against off-machine optical measurements for the same tools, this method allows for the identification of the shape deviations of the actual tool regarding the theoretical geometry defined for it with an accuracy of 0,1 µm. Next, the evolution of the grinding process state as the tool wears off has been analysed. The University of Bremen has worked on the realisation of cutting tests while monitoring several process signals. When comparing the obtained signal values and their evolution with the processing time, together with the appearance of the tool wear, correlations have been found that could later be used for the in-line analysis of the process state and estimation of the generated process quality. The data generated on tool wearing and process signal evolution has been employed by the University of Leuphana for the development of a statistical analysis tool for the in-line evaluation of the state for the grinding process. Once developed a prognosis engine for the identification of the process state, a software tool with a user friendly human interface has been developed. This tool can help on identifying process instabilities and quality deviations on the machined part. Also, it can provide the machine operator with recommendations for the modification or stopping the process in order to generate the desired part quality and avoid the scraping of parts.