Development of a grindingdrilling technique for holing optical grade glass

This study presents the development of a grindingdrilling technique for an innovative bench-top drill that combines micro-EDM with grinding and drilling to fabricate micro-holes in optical grade glass. Firstly, a novel diamond-tool, made with copper-based sintered alloy, is designed and fabricated on-line into a harbor-shaped structure with a hollow shaft and negative back rake-angles. Constructed reverse co-centric micro-hole EDM-drilling and reverse w-EDM facilitate on-line machining of the diamond-tool, which can then be directly utilized to drill micro-holes in optical glass and quartz. Application of a load-cell that detects the drilling force in real-time, providing feedback for fine tuning the feed-rate of the tool is proposed. Experimental results show that excellent geometric and dimensional accuracy of micro-holes can be achieved. The estimated reasonable tool life is determined at a machining number of 30 times. The proposed grindingdrilling technique is simple, cost effective, and can significantly contribute to the precision micromachining industry.