Abstract
The cutting edges of micro-milling tool undergo degradation with time, in the form of continuous abrasion and intermittent chipping. As a result, the cutting tool looses its original profile and consequently affects the quality of molds and dies manufactured using micro-milling process. This work therefore focuses on understanding the physics and mechanism of tool wear in micro-milling as function of tool life, and to model the transient degradation of cutting tool, which was not investigated in-depth in the literature. Extensive micro-milling experiments were done till the end of tool life, to investigate cutting edge degradation. Further, analytical as well as empirical models were developed to predict continuous abrasion interrupted by chipping, and to determine cutting edge profiles as a function of tool life. The abrasion wear model involved modifying Archard’s equation and evaluating tool wear coefficient empirically using a novel pin-on-disk device. The interrupted chipping wear phenomenon during micro-milling was identified by locating sudden drop in resultant forces on the tool. The chipping wear was then modeled using the dimensions of the chipped portions, extracted from the tool images captured in-situ. It was observed from the experiments that the length (C) of the chipped portions of the cutting edges was between 15.76 to 96 μm, whereas, their width (H) was between 7 to 29 μm, and they were found to have a positive correlation. The chipping load estimated from the resultant force, and the load inclination angle evaluated from the chipping model were found to have an inverse correlation, and varied between 1.23 to 3.75 N, and 69 to 25° respectively. The proposed abrasion and chipping wear model jointly gave transient progression of total volumetric tool wear area, and consequent cutting edge profiles over the tool-life cycle. The proposed tool wear model predicted the total wear within 9.3% of the experimental values.
Published Version
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