Core drilling versus chisel drilling with an eye on sustainability

Drilling constitutes about 40% of all machining operations performed. In this perceptive paper, we take a fresh look at the process of drilling with an eye on sustainability. We first explore the cutting regimes along the classical, chisel-type drill's cutting tip and look for the pressure coefficient distributions along the length of the lip. We then focus our attention on the outermost regions where mostly 2-D cutting takes place and leading to efficient machining. These regimes are those that core (periphery) drills cut through creating the hole by slicing through the hole perimeter while leaving the hole's internal regions untouched. Several experiments and calculations were conducted with the results confirming that generated forces are smaller for periphery drilling as compared with chisel-type drilling. With the considerable energy savings either directly through cutting power or indirectly through reuse, it is proposed that traditional drilling are replaced by periphery drilling whenever feasible, e.g., drilling of through holes with relatively large diameters. This can be performed by tools that resemble the 'core drill' after being redesigned to address several potential processing drawbacks. Tremendous savings in power can be realized (including corresponding reduction in heat generation and tooling temperature) while yielding longer lasting tools as well as more durable products. Several other potential sustainability-related benefits are also realized.