Study of the Relationship between Cutting Speed, Tool Wear and Machining Forces in Turning with Carbide Tool

Abstract

The understanding of machining processes comprises the study of phenomena such as: chip formation, cutting forces, tool wear mechanisms and the influence of the cutting parameters and machined materials on them. The aim of this work is to analyze the tool wear effects on machining forces during machining of AISI 1040 and 1045 carbon steels with carbide tool. Long-term machinability tests were performed, in which cutting force, feed force and tool wear were measured. Tool life results were analyzed, with best tool lives found for the AISI 1040 steel for all tested speeds. The other variables were analyzed as function of both time and tool wear. On the time domain, strong dependencies were found for both materials for tool wear, cutting force and feed force. The relationship between cutting force and tool wear showed good correlation for both materials, and the same was observed for feed force and tool wear relationship. Weak influence of cutting speed was observed on the relationship between tool wear and machining forces, which suggest that a single equation can describe them for all studied conditions with reasonable accuracy. The regression results are able to predict cutting forces as a function of tool wear with an average error of about 2.6 % during machining of AISI 1040 and 5.2 % for AISI 1045 steel. For the prediction of feed force as a function of tool wear, the average error is about 5.6 % for AISI 1040 and 7.0 % for the AISI 1045 steel, since a restricted domain is established. Data analysis showed a discontinuity in the behavior of feed force as a function of tool wear near the end of the life of the tools for most tests performed with AISI 1045 and some tests with AISI 1040 that suggest backwall wear, which was further evidenced by sudden change of chip form near the end of tool life in AISI 1040 steel.