Study on grinding force modelling and ductile regime propelling technology in micro drill-grinding of hard-brittle materials

This study developed a new micro drill-grinding tool for precision micro-drilling of hard brittle materials, such as alumina ceramic and soda-lime glass, and analyzed the material removal mechanism of micro drill-grinding. A model of the micro drill-grinding force Fz was built using a physical method based on the undeformed chip thickness hm. Experiments examining micro drill-grinding were conducted on a micro-machining desktop for micro drill-grinding. The failure modes and the lifespan of this new tool were investigated compared to the conventional micro-grinding method. The variation of the micro drill-grinding force was investigated, and the effects of rotation speed ng are discussed. The change law of Fz was revealed based on experimental results, which also verified the scientific internal logic relation of the model that this study proposes. The brittle–ductile transition in the micro drill-grinding of hard brittle materials was investigated. A ductile regime propelling technology of a resin coating was proposed and successfully developed in this study. This paper demonstrated that this technology could effectively propel the ductile-regime of soda-lime glass in micro drill-grinding and reduce the fracture size. Experimental machining examples indicate that the average fracture size is reduced from 239.58 μm to 15.11 μm, and the ductile regime is propelled from 50 nm/rev to above 200 nm/rev. The technique and knowledge that this study proposes could provide a significant contribution to the precision micro-machining of hard brittle materials.