Torque and Thrust Parameters in Drilling Using Dimensional Analysis

Abstract

The application of dimensional analysis to the drilling process has provided relevant dimensionless groups for the prediction of torques and thrust and evaluating the influences of several operating variables. Drill design, operating conditions and various materials properties are considered. The applicable experimental procedures are thereby indicated to identify possible strain rate and/or speed effects. Similarity laws are established for large drills (over 1/2 inch diameter), although the same general forms are found for smaller drills. In conjunction with a mathematical analysis, strain rate and speed effects are found to be equivalent, but do not influence torque and thrust, other things being equal. The effects of pilot holes and point angle parameters are also investigated experimentally. The dimensional analysis-similarity approach allows hypothesizing various independent parameters and establishing their influences, if any. Experimental results here are compared with others’ data in terms of the dimensionless groups and are in general agreement.