<title>Abstract</title>
In the automated machining processes, tool damage should be managed to assure product qualities, promote machine tool performance and reduce production time and cost. In drilling process, the cutting process changes along the cutting edge; and the tool wear is not uniform. This paper presents a monitoring of the tool wear distribution with measuring the cutting force in drilling with a twist drill. The cutting force increases with the cutting area in the edge penetration into workpiece in drilling. In the proposed approach, the cutting edges are divided into small discrete segments. The increasing rate of the cutting force at a segment is associated with the normal forces loaded at the cutting area. The normal force distributions, then, are estimated for the cutting edge damage. The widths of flank wear lands along the cutting edge is monitored based on the increase of the normal force distribution. The cutting tests were conducted to validate the presented approach with measuring the cutting force in drilling of carbon steel. The presented approach estimates the tool wear distribution on the edge with the cutting time. The average stress distribution loaded on the flank wear land is also estimated in the regression analysis.