Application of small-hole dry drilling in bimetal part

In dry drilling, the drill tip will encounter a very severe condition in the cutting zone, especially in deep- and small-hole cases, causing the drill to fail at a high rate. This paper describes an experimental study of small-hole dry drilling in a bimetal material (powder metal steel and aluminum alloy). The study consists of failure mode analysis, coating, tip geometry and cutting parameter impact on the dry drilling process. The results show that suppressing aluminum buildup on the drill surface, caused by the heat generated during machining, is a critical strategy to make dry drilling a success. The experiments suggest that air cooling and cutting speed are the most important process parameters to be considered in dry drilling. Through a better understanding of the impact of process parameters, an optimized drilling strategy was developed and validated. It could reach 600 bimetal holes drill life target, which is more than three times of the initial baseline process.