Precision punching: A new method in hole-making on composite panels

Abstract The strength of an assembly for composite panels depends on quality of the produced holes. In practice, industries produce holes on composite panels by drilling. However, this process is time-consuming, costly, and less flexible in terms of hole geometry. In this chapter, we propose a new method for hole-making using punching. Compared to drilling, punching may not cause peel-up and pull-down edges due to rotational drill bits. However, the applied force during punching may cause severe damage around the holes. Punching is a fast process that is cost-effective and can produce various geometry. The potential of the punching process to replace drilling is determined based on various design parameters. In this chapter, we observe the effect of die clearance and puncher profiles on punched hole quality on composite panels in terms of hole diameter, complete shearing, and delamination or damage area. Six types of puncher profiles with minimum die clearance (1%) were fabricated. Results show that a smaller die clearance increases the accuracy of the punched hole size, while incomplete shearing decreased as the die clearance decreased. Regarding puncher profile, the conical-shaped puncher produced the least defects in terms of delamination and yielded an acceptable amount of incomplete shearing compared with the other punchers.