Tool feed influence on the machinability of CO_2 laser optics

Abstract

Influence of tool feed on reflectivity of diamond-machined surfaces was evaluated using materials (gold, silver, and copper) from which CO2 laser optics are primarily produced. Fifteen specimens were machined by holding all machining parameters constant, except tool feed. Tool feed was allowed to vary by controlled amounts from one evaluation zone (or part) to another. Past experience has verified that the quality of a diamond-machined surface is not a function of the cutting velocity; therefore, this experiment was conducted on the basis that a variation in cutting velocity was not an influencing factor on the diamond-turning process. Inspection results of the specimens indicated that tool feeds significantly higher than 5.1 μm/rev (200 μin./rev) produced detrimental effects on the machined surfaces. In some cases, at feeds as high as 13 μm/rev (500 μin./rev), visible scoring was evident. Those surfaces produced with tool feeds less than 5.1 μm/rev had little difference in reflectivity. Measurements indicated that their reflectivity existed in a range from 96.7% to 99.3% at 10.6 μm.