Fig. 1. Schematic diagram of fly-cutting and its arc profile

Fig. 2. Schematic diagram of cutting and its spiral line process path

Fig. 3. Schematic diagram of diamond tool parameters

Fig. 4. Initial surface quality of ZnS crystal element

Fig. 5. Roughness test results of ZnS flat element processed by fly-cutting with different parameters of diamond tools

Fig. 6. Effect of spindle speed on surface roughness

Fig. 7. Effect of cutting depth on surface roughness

Fig. 8. Effect of feedrate on surface roughness

Fig. 9. Roughness test results with the optimal processing parameters of fly-cutting

Fig. 10. Analysis of the cutting parameters with single variable method

Fig. 11. Roughness test results with the optimal processing parameters of cutting