CUTTING FORCES AND SURFACE ROUGHNESS IN MACHINING Al/SiCp COMPOSITES OF VARYING COMPOSITION

Abstract

Knowing that the machined surface roughness of Al/SiCp composites is linked to its performance, this paper presents an elaborative experimentation using Taguchi methods on four composites to analyze the effects of size (15 μm and 65 μm) and volume fraction (20% and 30%) of reinforcements in the composites on machining forces and machined surface roughness. The independent variables in the experiment were: tool nose radius, cutting edge geometry, feed rate, cutting speed and depth of cut. The results show that, of the three machining force components, only radial force shows significant dependence on composition of composites. The machined surface roughness was found to be more sensitive to a change in size than to volume fraction of reinforcement in composites. However, all the independent variables, except the cutting speed, cause a statistically significant effect on the machined surface roughness for all composites. An analytical model giving a correlation between the machined surface roughness and the ratio of cutting forces was formulated based on the geometry of work-tool contact. The predicted surface roughness using the model was found to agree well with the experimental values, especially when the tool nose radius is less than the depth of cut.

Keywords:

• cutting edge geometry
• cutting forces
• machining
• metal matrix composites
• surface roughness
• Taguchi method

ACKNOWLEDGMENTS

The authors wish to acknowledge the DST-FIST Precision Prototyping Cell sponsored by DST, Government of India, at Machine Tools Laboratory, IIT Bombay, for providing facilities to carry out this experimental work. The first author, Uday A. Dabade, wishes to acknowledge the support of management of Walchand College of Engineering, Sangli, for giving him an opportunity to carry out this work at IIT Bombay under QIP scheme.

Notes

*Dummy level to fulfill the requirement of L ₂₇ orthogonal array and to provide more precise information about the effect of 0.8 mm tool nose radius (Phadke, 1989).

Key to abbreviations: FR=Feed rate; CS=Cutting speed; DOC=Depth of cut; TNR=Tool nose Radius and IG=Insert geometry.

Key to abbreviations: FR=Feed rate; CS=Cutting speed; DOC=Depth of cut; TNR=Tool nose Radius and IG=Insert geometry.

*Bold value indicates the significance at 95% confidence level.