Investigation of burr formation and surface roughness in drilling engineering plastics

Abstract

Engineering plastic components are generally drilled owing to the need for bolted, riveted or screwed structures, but formation of burr induces some difficulties in the assembly stage. The most practical method for deburring is to select proper cutting parameters and tool during drilling. This study investigates the formation of the exit burr height during drilling of ultra-high molecular weight polyethylene under three different cutting speeds (30, 40, 50 m/min) and feeds (0.006, 0.0125, 0.250 mm/rev). Also, three different types of HSS-based tools such as TiN-coated, TiCN-coated and uncoated HSS twist drill tools were used. The effects of cutting parameters and tools were the controllable factors in the experimental study. Experimental design and multiple regression analysis were utilized in determining the optimal parameters. The results showed that highest feed (0.025 mm/rev), lowest cutting speed (30 m/min) and uncoated HSS tool gave lower burr height due to the less deformation of the work material. Surface roughness of the drilled holes was also measured and almost similar effects of the controllable factors on surface roughness and burr height were observed. Finally, a relation between the burr height and type of chip was observed and it has been observed that the process variables increasing burr height gave irregular and highly deformed chips.