Impact of Cleaning Efficiency on Disc Cutter Drilling Performance

Abstract

Large diameter drilling operations, including tunnel boring and raise boring, are capital-intensive projects. As such, proper estimation of time and cost is critical to the planning of the drilling project. To arrive at the correct estimation of the drilling time during the drilling phase, accurate prediction of the drilling performance is needed. In large diameter applications, disc cutters are the primary cutting tools, hence, several investigations have focused on developing accurate estimation of disc cutter forces. Other studies have also sought to understand the impact of rotary speed and cutter geometry on drilling performance. This study seeks to contribute to existing body of knowledge by evaluating the impact of cuttings cleaning efficiency on disc cutter drilling performance. This technical paper presents the results of two sets of drilling experiments. Both experiments were conducted under atmospheric condition on the same granite block using same rotary cutting machine and tri-disc disc cutter with tungsten carbide inserts. Same drilling parameters were applied during each of these experiments. However, the difference lay in the adopted cuttings evacuation method. One drilling procedure adopted the dry method wherein the cuttings were evacuated with vacuum while in the second procedure, the cuttings were cleaned using the jetting action of a high spray nozzle. The results of these experiments show how much influence the cleaning efficiency has on the disc cutter drilling performance.