Experimental Investigation on the Influence of Tool Geometry in Minimum Chip Thickness of Microendmilling Using Cutting Force Analysis

Abstract

Minimum uncut (tm) chip thickness is the promising factor of the microendmilling process, which is affected by many factors. The tool geometry is one among them. In this work, the effect of different tool geometries, two flutes and four flutes of microendmill (500 μm diameter), are investigated, during slot milling of copper alloy (BSS 249) by considering the surface roughness (Ra) and cutting forces. The results show that the feed rate has more impact on the Ra. A higher order of Ra value is observed with the two flutes microendmill than that of with four flutes microendmill, due to the closer tool path generation of the subsequent passes of the four flutes. It is also observed that the transition of chip formation from interrupted chips to continuous chips has occurred with two flutes and four flutes. From the cutting forces analysis, it is found that the feed force (Fy) is greater than that of the transverse forces (Fx) irrespective of the tool geometry. The behaviour of cutting forces also helps to identify the minimum uncut chip thickness (tm). The angular shifting of the cutting forces is also observed concerning the tool geometry. The material removal mechanism reveals that the ploughing effect is more dominant than that of the shearing effect with two flutes microendmill. The present investigations have shown that four flutes microendmill is more suitable for tool-based microendmilling in order to achieve better Ra with minimum cutting forces.