RELATION BETWEEN DRILL BIT TEMPERATURE AND CHIP FORMS IN DRILLING OF CARBON BLACK REINFORCED POLYAMIDE

Abstract

Polyamides have many application fields due to their good mechanical strength, high impact strength, good sliding properties etc. Recently, electrically conductive polyamides can be produced by adding carbon black, graphene, metals and carbon nanotubes and their usage have increased. Polyamides are generally manufactured by injection molding and extrusion method but drilling is often needed for the final product. In literature, there are not many studies on the drilling of polyamides and polyamide composites. In this study, drill bit temperature and chip forms were investigated during the drilling of unreinforced polyamide and carbon black reinforced electrically conductive polyamide. Drilling experiments were performed at three different feeds and cutting speeds. Depending on the experimental results, the drill bit temperature increased with increasing the cutting speed and decreasing the feed. Higher drill tip temperatures were measured in the drilling of carbon black reinforced polyamide than that occurred in the drilling of unreinforced polyamide. The chips were more deformed at high cutting speed and low feed. In addition, the chip forms of carbon black reinforced polyamide were observed more regular than that of unreinforced polyamide due to the fact that the chips of carbon black reinforced polyamide could conduct the heat to the drill bit and they were less affected by the heat.