Sustainability and tool wear of titanium alloy thread cutting in dry and cryogenic conditions

Abstract

The article is devoted to the study of the effect of cryogenic cooling on the tool wear in thread turning tests. The tool wear and its influence on the thread accuracy were investigated. Two different grades of titanium alloys were used for comparative purposes. The excellent performance characteristics of titanium alloys pose machining problems, causing high unit forces at the edge of the tool leading to chipping and premature tool failure. In turn, the low thermal conductivity of pure titanium affects the heat distribution in the cutting zone. The heat is not absorbed by the material being machined but accumulates in the tool, causing an increase in diffusion and chemical wear. The results of cutting tests using liquid nitrogen showed lower values of wear on the major and minor tool flank. The edge reduction of the tool was also significantly less during cryogenic machining. The analysis of the formation of wear marks and the blade wear mechanisms was carried out for the tool rake face. The tests were carried out using the SEM method and confirmed by EDS analyses. In order to compare the course of tool wear over time, a mathematical model was developed, which results from the course of phenomena during cutting. It consists of two complementary equations. The first equation is characteristic for the first cutting phase and results from the loads imposed on the blade and aims at thermodynamic equilibrium. It is a period of stable tool operation and constant wear intensity. The second equation concerns crossing the equilibrium point followed by the process of accumulation of elementary wear phenomena. These phenomena accumulate until the blade is completely worn-out. The use of blade wear development models to determine the expected blade life allowed to confirm the beneficial effect of cryogenic cooling on the course of the blade wear process when cutting threads for two different titanium alloys.

A study on the temperature of cutting fluid in the micro-cutting of commercially pure titanium

“…Zawada-Tomkiewicz et al [6], titanium and its alloys can be considered difficult-to-cut materials due to the low thermal conductivity and their chemical reactivity at high temperatures. The titanium and its alloys are widely used in aerospace, medical science, and automobiles due to the low weight-tostrength ratio and high corrosive resistance, for example.…”

Influence of different cutting edges caused by tool wear on cutting process of titanium alloy TC21 based on finite element model

“…With tool wear becoming the most serious problem of titanium alloy cutting, numerous studies have been conducted to analyze the wear mechanism and find methods to decrease the tool wear for extending the tool life. 5,[13][14][15][16][17][18][19][20][21][22] Pramanik et al 13 analyzed the causes of chip formation and tool wear in the cutting of titanium alloy and confirmed that the main factors of tool wear include plastic deformation, thermal cracking, abrasion and diffusion. Biermann et al 14 surveyed the cryogenic cutting process of two different titanium alloys and analyzed the different behavior and tool life in cutting processes under cryogenic conditions.…”