Influence of Workpiece Hardness on Tool Wear in Profile Micro-milling of Hardened Tool Steel (original) (raw)
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The International Journal of Advanced Manufacturing Technology, 2019
Micro components have been demanded increasingly due to the global trend of miniaturization of products and devices. Micro milling is one of the most promising processes for micro-scale production and differs from conventional milling due to the size effect introducing phenomena like the minimum chip thickness, making the prediction of micro milling process hard. Among challenges in micro milling, tool life and tool wear can be highlighted. Understanding tool wear and modelling in micro milling is challenging and essential to maintaining the quality and geometric tolerances of workpieces. This work investigates how to model the diameter reduction of a tool caused by tool wear for micro milling of H13 tool steel. Machining experiments were carried out in order to obtain cutting parameters affecting tool wear by considering the diameter reduction. Dry full slot milling with TiAlN (titanium aluminium nitride)-coated micro tools of diameter d = 400 μm was performed. Three levels of feed per tooth (f z = 2 μm, 4 μm and 5 μm) and two spindle speed levels (n = 30,000 rpm and 46,000 rpm) were used and evaluated over a cutting length of l c = 1182 mm. The results show that lower levels of feed per tooth and spindle speed lead to higher tool wear with a total diameter reduction over 22%. The magnitude of the cutting parameters affecting tool wear was determined by ANOVA (analysis of variance), and the model validation meets the statistical requirements with a coefficient of determination R 2 = 83.5% showing the feasibility of the approach to predict tool wear using diameter reduction modelling in micro milling.
Tool Wear in Micro-Endmilling: Material Microstructure Effects, Modeling and Experimental Validation
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Investigation on tool wear and tool life prediction in micro-milling of Ti-6Al-4V
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a b s t r a c t a r t i c l e i n f o Short tool life and rapid tool wear in micromachining of hard-to-machine materials remain a barrier to the process being economically viable. In this study, standard procedures and conditions set by the ISO for tool life testing in milling were used to analyze the wear of tungsten carbide micro-end-milling tools through slot milling conducted on titanium alloy Ti-6Al-4V. Tool wear was characterized by flank wear rate, cutting-edge radius change, and tool volumetric change. The effect of machining parameters, such as cutting speed and feedrate, on tool wear was investigated with reference to surface roughness and geometric accuracy of the finished workpiece. Experimental data indicate different modes of tool wear throughout machining, where nonuniform flank wear and abrasive wear are the dominant wear modes. High cutting speed and low feedrate can reduce the tool wear rate and improve the tool life during micromachining. However, the low feedrate enhances the plowing effect on the cutting zone, resulting in reduced surface quality and leading to burr formation and premature tool failure. This study concludes with a proposal of tool rejection criteria for micro-milling of Ti-6Al-4V.
Proper setting of cutting conditions is critical for the performance of micro endmills in micro milling of hardened tool steels. In this paper, the influence of the cutting parameters on the wear behaviour of micro square endmills is presented. The selected parameters are cutting speed, depth of cut, and feed per tooth; Central Composite experimental Design (CCD) was used for a statistical analysis of the influence of these parameters. A quadratic model was fitted to describe the performance of the tool wear; the ANOVA analysis shows that the quadratic model gives a good prediction of the experimental results. On considering the magnitudes of the coefficients it is seen that the feed per tooth has a greater influence on the tool wear than cutting speed and depth of cut within the tested process window. By applying this method, the micromilling process can be planned to achieve an optimum tool wear performance for a tool-workpiece combination.
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In this study, it is aimed to investigate the surface roughness of cutting tools during the machining of AISI 304 stainless steels, the life of cutting tools and the cutting forces that occur during cutting and machining. The main features of stainless steels are: high corrosion resistance, ductility and high tensile strength. Stainless steels contain elements such as chromium, nickel and molybdenum which affect the machinability in the negative direction; therefore it is very difficult to process stainless steels. This work was carried out using covered cutting tools. The work was carried out at different cutting depths and different feed rates without the use of cooling liquid. The life and wear mechanisms of cutting tools, cutting forces and surface roughness were investigated in relation to cutting parameters.