Effect of EDMed rake face grooves on the chip breaking capability of twist drills during deep hole drilling of Al 6061 aluminum alloy

ABSTRACT

Deep hole drilling of ductile materials like Al6061 with conventional twist drills is challenging due to premature tool failure caused by chip clogging. Chip breakers, in the form of grooves of varying angles (0°, 5° & 10°) and depth (0.4 & 0.5 mm), created using EDM on the rake face, are proposed to overcome chip clogging. Tool wear, hole roughness, and diameter deviation were measured and analyzed along with chip morphology study for the six grooved tools and compared with plain drill. The grooved tools were successful in breaking the chips which allows for easy evacuation without any clogging. Grooved drills produced desired spiral chips compared to string chips produced by plain drill thus resulting in lesser tool wear rate. While the grooved tools showed stable but slightly higher roughness values, the conventional tools exhibited a linear increasing trend as the drilling progressed. The machined hole surfaces had defects such as feed marks, pitting, grooves, and burnished surfaces. The grooved tools produced comparatively more diameter deviation probably because the well broken chips entered into the drill land/hole surface space. From the results it is clear that groove angle and depth have significant effect on the drill machinability characteristics.

KEYWORDS:

• Deep hole drilling
• edmedgroove
• rake face
• chip breaking
• clogging
• spiral chips
• surface finish
• hole diameter deviation

Acknowledgments

The authors thank The Department of Science and Technology, Government of India for funding this work under the DST - Early Career Research award (File Number: ECR/2017/000893).

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by the Science and Engineering Research Board [ECR/2017/000893].