Experimental Investigations on Tool Path Strategies in Ball-End Milling

Abstract

AbstractThe selection of the optimal tool path strategy and appropriate cutting conditions, especially in the machining aspects of free form surfaces are important to achieve higher productivity. In this work, optimal tool path selection for machining concave surfaces is carried out to achieve minimum surface roughness (Ra), cutting forces and machining time in ball-end milling of aluminium alloy 6061 (Al 6061). Various tool path strategies including 3D offset, raster, concentric, radial zig-zag, zig, and concentric zig-zag are employed. The cutting parameters considered were feed rate, spindle speed and step over. Design of experiments (DoE) along with the statistical analysis of variance (ANOVA) and mean plots are used to determine the significant parameters and their levels for each tool path strategy. Conflicting results were obtained from the ANOVA and the mean plot analyses, to achieve optimum levels that led to lower surface roughness, cutting forces and machining time. It is observed that lower values of surface roughness and cutting forces are obtained with the low level of feed rate and step over in all six tool path strategies. However, high feed rate and step over the lead to decreased machining time. Hence, grey relational analysis is carried out considering multiple performance characteristics such as minimum surface roughness, cutting forces and machining time, and optimal combinations of the milling process parameters for each tool path strategies are identified.KeywordsBall-end millingTool path strategyAluminium alloy 6061Surface roughnessCutting forcesMachining timeGrey relation analysis