Temperature analysis in fiber metal laminates drilling: Experimental and numerical results

Drilling process of fiber metal laminates (FML) requires a proper design of the processing parameters to prevent the occurrence of several issues and mini mize defects, which can be detrimental for the integrity of the parts. These aspects become more critical in dry machining used in aeronautic field. In this scenario, the monitoring of process temperature is crucial to obtain useful information for machining optimization since many critical factors, such as matrix burnout, fiber pull-out and delamination, depend on the heat generated during the machining. The aim of this work is to monitor the temperature measured on the tool and workpiece during dry drilling of Al/GFRP (GLARE) and Al/CFRP (CARALL) hybrid laminates. The influence of the cutting speed on the temperature trends was analyzed. Two different set-ups were designed to measure the temperature on the tool, near the cutting edge and on the flank, and inside the laminate, in both the metallic and the composite parts. In addition, a numerical model to analyze the process temperature trend during dril ling has been developed. The increasing the spindle speed from 1500 to 8000 rpm resulted in a decreasing of maximum temperatures of approximately 10 C on the tool tip and on the flank for the GLARE, and of almost 20 C in the CARALL lam inates. The numerical simulation also pointed that the temperature fields is dic tated by the thermal properties of carbon and glass fibers: temperature profiles within the CARALL were found smoother than those observed in GLARE.