Machining of brittle materials: micro milling of glass

The present study investigated the applicability of micro milling method in processing of glass material. Glass material has many fine chemical, physical and mechanical properties. It is widely used in high-technology fields such as aerospace, optics and biomedical. However, glass is known as difficult to machine material because of its tendency to brittle fracture during machining. In order to produce part with a good surface quality, glass is processed in liquid or viscous state. Conventional machining results in poor surface quality and sometimes fracture of the part. This study investigated the applicability of micro milling method in processing of glass material. The effect of cutting parameters, such as cutting speed, feedrate, depth of cut and lead angle on generated surface quality and cutting forces was evaluated via surface examination under an optical microscope and cutting force measurements with dynamometer. Experimental results showed that selection of right cutting parameters is extremely important and it has a direct effect on cutting mechanism, cutting forces and generated surface quality. An evaluation of machined samples showed that the generated surface quality drastically decreased with the increase in the amount of removed material. Lower depth of cut and feedrate resulted in less cracks formed on machined surface. Additionally, it was observed that the increase in cutting speed resulted in better surface quality. The best surface quality of machined soda-lime glass sample was obtained at cutting speed 10 m/min, feed per tooth 1 mu m/tooth and depth of cut 10 mu m cutting parameters, respectively.