CHARACTERISTICS OF MICROCUTTING FORCE VARIATION IN ULTRAPRECISION DIAMOND TURNING

Abstract

An investigation of the characteristics of microcutting forces in diamond turning of crystalline materials is presented. The characteristics of the cutting forces were extracted and analyzed using statistical and spectrum analysis methods. A series of cutting experiments were done on a copper alloy and copper single crystals with different crystallographic orientations. Experimental results indicate that there exists a dominant frequency component and a periodicity of fluctuation of the cutting forces per workpiece revolution in the diamond turning of a single crystal material. The periodicity is closely related to the crystallographic orientation of the material being cut. As the depth of cut increases, the influence of crystallographic orientation of the single-crystal materials on microcutting forces is found to be more pronounced. Moreover, the cutting force ratio between the mean thrust force and the mean cutting force is found to vary with the depth of cut, and a large ratio was observed at a small depth of cut. These findings help to explain quantitatively the periodic fluctuations of microcutting forces (and hence the materials-induced vibration) in ultraprecision diamond turning, which are not encountered in conventional machining.

Keywords:

• Comparative strength
• Cutting force
• Cutting force ratio
• Crystallographic orientation
• Dominant frequency
• Grain diameter
• Materialsinduced vibration
• Periodicity
• Polycrystalline aggregate
• Single crystal
• Spectral analysis
• Statistical analysis
• Thrust force
• Ultraprecision diamond turning
• Variation

7.0 ACKNOWLEDGMENT

The authors would like to express their sincere thanks to the Research Committee of The Hong Kong Polytechnic University for the financial support of the research.