Analysis of drill bit penetration states in the process of stepwise bone drilling

Drilling is a solid material removal process that makes use of a spinning cutting tool to create a circular crosssectional hole.During drilling, it is important that states of drill bit penetration be observed so that drilling action can be adjusted or terminated to prevent failures.This paper presents the measurements and analysis of the drilling states in stepwise bone drilling process (pre-drilling, scraping, main drilling, and breakthrough states).Drilling tool interaction signals acquired from the drilling process were used for identifying each state of drilling.Experimental results show that different drilling states can be distinguished by considering patterns of peaks in the motor current measurement signal.The state of drilling breakthrough, which is usually the most important state, can also be recognized, providing the benefit of preventing excessive drilling, if needed, especially in case of critical bone surgery.