Milling of Superhard Materials at an Ensured Rational State of the Technological Cutting System. Part 2

Abstract—Materials with hardness gradients are in high demand in the aerospace and military industries, and the demand is expected to grow. There is experience in producing parts with a base material hardness of about HRC 40 and a surface hardness of HRC 65 or more. These hardened surfaces are called high hardness coatings. Machining these high-hardness coatings encounters significant challenges and requires the use of cutting tools such as end mills and face mills. Currently, there are no systematic guidelines available for this machining process, and there are no recommendations for maintaining optimal cutting system conditions. The milling characteristics of these high-hardness coatings are considered. The aim of the work. The aim of the work is to determine how to maintain optimal performance of the machine–fixture–tool–workpiece cutting system on milling high-hardness parts to extend tool life. Research objectives. (1) To enhance the cutting tool performance. (2) To develop the criteria for assessing and controlling the current condition of the cutting system. (3) To predict the cutting system state and maintain its optimal performance. Research techniques. Experimental analysis, computational modeling, and acoustic emission monitoring are used. Novelty. The scientific novelty lies in (1) the establishment of criteria for real-time monitoring of the current state of the cutting system, and (2) a predictive methodology that allows both predicting the state of the cutting system and controlling its operating parameters. Results. The study confirmed that high-efficiency milling of high-hardness materials is possible when all critical requirements, namely, machining productivity, surface finish quality, and tool life of carbide inserts, are met. Conclusions. The criteria developed for the estimation of the cutting system state provide real-time process control on maintaining the required workpiece surface quality, machining productivity, and tool life.