Increase Hole Flangeability by Improvement of Pierced Surface Quality with Shaving Process

In hole flanging process, one of serious problems encountered is crack generated on the hole edge leading to poor hole flangeability. This is because the pierced surface of punched hole, consisting of rollover, burnish, fracture, and burr, is not of good quality. This research is to improve the quality of pierced surface by shaving process. The tool is designed to have the step taper shaped punch with taper angle of 6°. The tested sheet material is SPCC with a thickness of 1 mm. The studied parameters include shaving allowances varied at 2%, 5%, and 15% and clearances varied at 0.5%, 1%, and 2% of material thickness. The experimental results from the shaving process show that using the small percentage of clearance (≤0.5%T) and the small percentage of shaving allowance gives better pierced surface quality. Experimental conditions of larger percentage of shaving allowance give poor quality of pierced surface. The experimental results from the hole flanging process show that good quality of pierced surface (with larger burnish height) results in better hole flangeability. The pierced part with burr-down position (burr on the punch side in hole flanging process) results in better hole flangeability than the burr-up position (burr on the die side).