Ductile-Regime Machining of Optical Glasses by Means of Single Point Diamond Turning.

This study presents experimental results on machining of optical glasses by using ultra-precision lathe. Four machining types, which are subdivision of ductile and brittle modes, are defined for a minute description of experimental results. The machining experiment for BK7 was tested in several atmospheres. Damage-free cutting mark can be obtained within 1-micrometer tool infeed in methanol and ethanol atmosphere. An evidence for about 0.5 micrometer spring-back in BK7 was obtained from microscopic observation and experimental data. Results of the cutting several materials are presented and discussed. Comparing maximum depth of groove in the ductile mode and the critical depth of tool indentation calculated from previous theoretical analysis, it was revealed that nearly same amounts of depth are confirmed in SiC and vitreous silica, but that in BK7 is different from theoretical one in a figure.