National Research Council trying to improve drills, bits

The National Research Council has been involved in studies which it hopes will prove useful to the diamond drilling industry. The current status of research seeks to refine testing devices for the assessment of the performance of diamond drill bits, and to optimize drill bit composition and drilling conditions. A recent study undertook a series of tests with the objective of improving the service life, and particularly the rock cutting performance, of diamond tools. The rationale for the study was the fact that no private research is done in Canada since most diamond tools are imported. The Council sees a great incentive to improve the performance of these tools.

Earlier work tested for improved adhesion of the diamond to the matrix and for the development of testing apparatus which could characterize the penetration speed of diamond tools. The test machine can reach drilling RPMs of up to 2,000 and pressures of up to 17 MPa.

More than 400 tests were done under different conditions, varying the diamond size and volume, the matrix hardness, the drilling medium, and the drill pressure and RPMs.

Diamond size varied from 60 to 20 mesh, while volumes varied from 5% to 40%. Matrix hardness varied from 69 to 89 HRB. The tests were done in three types of granite, varying from relatively soft to relatively hard. Drilling parameters included a pressure range of 3,000 to 12,500 KPa, while the RPM varied from 500 to 2,000.

Ultimately, the data base should be able to identify the optimum operating parameters under a given set of conditions which will allow for maximum drill penetration and minimum bit wear.