Tool Wear In High-speed Milling Research Articles

Investigation on cutting forces and tool wear in high-speed milling of Ti-6Al-4V assisted by longitudinal torsional ultrasonic vibrations

Investigation on cutting forces and tool wear in high-speed milling of Ti-6Al-4V assisted by longitudinal torsional ultrasonic vibrations

Multiobjective Optimization of Surface Roughness and Tool Wear in High-Speed Milling of AA6061 by Machine Learning and NSGA-II

This work addresses the prediction and optimization of average surface roughness (Ra) and maximum flank wear (Vbmax) of 6061 aluminum alloy during high-speed milling. The investigation was done using a DMU 50 CNC 5-axis machine with Ultracut FX 6090 fluid. Four factors were examined: the table feed rate, cutting speed, depth of cut, and cutting length. Three levels of each factor were examined to conduct 81 experiment runs. The response parameters in these experiments were measurements of Ra and Vbmax. We applied a two-pronged approach that combines machine learning (ML) and a Nondominated Sorting Genetic Algorithm (NSGA-II) to model and optimize Ra and Vbmax. Four ML models were used to predict Ra and Vbmax: linear regression (LIN), support vector machine regression (SVR), a gradient boosting tree (GBR), and an artificial neural network (ANN). The input variables were the significant factors that affect the surface quality and tool wear: the feed rate, depth of cut, cutting speed, and cutting time. Several quality metrics were employed to quantify the performance of the models, such as the root mean squared error (RMSE), mean absolute error (MAE), and coefficient of determination (R2). As a result, SVR and ANN were found to have the best predictive performance for Ra and Vbmax. These models and the NSGA-II-based approach were then employed for multiobjective optimization of cutting parameters during high-speed milling of aluminum 6061. Fifty Pareto solutions were found with Ra in the range of 0.257 to 0.308 µm and Vbmax in the range of 136.198 to 137.133 μm. Experimental validations were then conducted to confirm that the optimum solution was within an acceptable error range. More precisely, the absolute percentage errors for Ra and Vbmax were 2.5% and 1.5%, respectively. This work proposes an effective strategy for efficiently combining machine learning techniques and the NSGA-II multiobjective optimization algorithm. The experimental validations have reflected the potential for applying this strategy in various machining-optimization problems.

PCD coating polishing effect on the tool wear in high-speed milling of graphite

The manufacture of molds with increasingly shorter deadlines and costs requires tool manufacturers to improve their manufacturing processes. One of the ways is improving their electrode machining, because this process will affect directly in the result of the dimensional precision and production time of the mold. The usage of graphite as raw material for electrodes is known to be highly satisfactory since the graphite has the advantage of machining faster and allowing a great variety of geometrical forms; however, its main disadvantage is that the graphite also has a high level of wearing during the machining process. The cutting-edge preparations are used in order to reduce the effects of this problem, increasing the durability of the tools. In that interest, this paper has researched the effect of edge preparations, through the polishing of the PCD coating, on the wear of tools, in milling of graphite electrodes. Therefore, experimental tests were performed with untreated and polished tools, with abrasive brushes, and by drag finishing. The tests consisted in machining electrodes with analysis of tool wear, roughness, and characterization of the tools. The findings indicate that the edge preparation results in modifications on the coating surface, reducing the roughness value by a mean of 23%, and in the case of drag finishing process, a variation of the values reduction, since this process is more reliable and reproducible. With regard to the tools’ wear, gains such as reduction of flank wear and a cutting length increase of up to 63% were noticed, in comparison with the original tools.

Investigations on surface microstructure in high-speed milling of Zr-based bulk metallic glass

Bulk metallic glasses (BMGs) are a relatively new group of metallic alloys with amorphous microstructure. BMGs have been increasingly used in industrial applications due to their high strength and high corrosion resistance. The microstructural evolution and the surface generation mechanisms in machining of BMGs and crystalline metal alloys are substantially different. This paper presents the investigations on surface microstructure and progressive tool wear in high-speed milling of Zr-based BMG. The crystallization of originally amorphous BMG material caused by the milling process was examined. The microstructure properties of BMG at amorphous and crystalline phases were determined. The effect of coolant on the progressive tool wear and the constituent element changes of BMG was investigated. The results provide new and comprehensive information on surface microstructure property in response to high-speed milling of Zr-BMG, and can guide the process planning in achieving desired surface property in milling of Zr-BMG components.

Influence of cutting tool geometrical parameters on tool wear in high-speed milling of Inconel 718 curved surface

High-speed machining provides an efficient approach for machining Inconel 718 with high quality and high efficiency. For high-speed milling of Inconel 718 curved surface, the geometrical characteristics are changing continuously leading to a sharp fluctuation of cutting force, which will aggravate the tool wear. As the wear mechanism of coated cutting tool is seriously affected by the cutting tool geometrical parameters, suitable geometrical parameters of cutting tool should be selected to avoid the cutting tool from being worn out very quickly. In this study, the influence of cutting tool geometrical parameters on tool wear in high-speed milling of Inconel 718 curved surface is investigated with coated cutting tool, and the cutting force in milling process is also analyzed. The results show that the cutting force variation can manifest the tool wear degree, and the failure type of coated cutting tool in plane milling and curved surface milling after the same cutting length is different. Furthermore, the cutting tool geometrical parameters seriously affect the tool wear and the tool life in high-speed milling of Inconel 718 curved surface. Concretely, the small rake angle has greater strength and has superiority, the relief angle increasing can enhance the tool life, and the tool life is decreased with the increasing of helix angle for the cutting tool, whose helix angle is larger than 30°. This study provides a theoretical basis for cutting tool wear mechanism and cutting tool geometrical parameter selection in high-speed milling of Inconel 718 curved surface, so as to guarantee the machining efficiency in high-speed milling of Inconel 718 curved surface.

Influence of spindle speed on tool wear in high-speed milling of Inconel 718 curved surface parts

High-speed milling, which provides an efficient approach for high-quality machining, is widely adopted for machining difficult-to-machine materials such as Inconel 718. For high-speed milling of Inconel 718 curved surface parts, the spindle speed which determines cutting speed directly is regarded as an important cutting parameter related to tool wear and machining efficiency. Meanwhile, because of the changing geometric features of curved surface, cutting force is changing all the time with the variation of geometric features, which influences not only tool wear but also machining quality significantly. In this study, the influence of spindle speed on coated tool wear in high-speed milling of Inconel 718 curved surface parts is studied through a series of experiments on considering tool life, cutting force, cutting force fluctuation, and machining efficiency. According to the experimental results, the appropriate spindle speed that can balance both the tool life and the machining efficiency is selected as 10,000 r/min for high-speed milling of Inconel 718 curved surface parts. In addition, the coated tool wear mechanism is investigated through scanning electron microscopy–energy dispersive x-ray spectroscopy analysis. The results show that at the beginning wear stage and the stable wear stage, the coated tool wear is mainly caused by mechanical wear. Then, with the increasing cutting temperature due to the blunt tool edge, the tool wear becomes compound wear which contains more than one wear form so as to cause a severe tool wear.

Cutting forces and tool failure in high-speed milling of titanium alloy TC21 with coated carbide tools

TC21 alloy is a new alpha–beta damage tolerance titanium alloy with high strength and high toughness. Little work has been done in the field of machinability analysis since this alloy was developed. The cutting forces and tool wear in high-speed milling of TC21 alloy with physical vapor deposition ((Ti, Al)N-TiN)-coated carbide tools under different cutting conditions were investigated in this article. The results showed that the cutting force component Fx was more dominant of the three components, and the cutting forces presented an increasing trend with the tool wear progress, which in turn deteriorated the cutting condition and accelerated the tool failure progress. The major tool wear modes in high-speed side-milling TC21 alloy with coated carbide were adhesion and chipping on the rake face along with chipping and transverse crack on the flank face. Moreover, there was obvious nose depression from both the rake face and the flank face. Chipping along the flank and rake faces was identified as the main factor responsible for the failure of the coated carbide tools during the milling of titanium alloy TC21.

Characterization of Tool Wear in High-Speed Milling of Hardened Powder Metallurgical Steels

In this experimental study, the cutting performance of ball-end mills in high-speed dry-hard milling of powder metallurgical steels was investigated. The cutting performance of the milling tools was mainly evaluated in terms of cutting length, tool wear, and cutting forces. Two different types of hardened steels were machined, the cold working steel HS 4-2-4 PM (K490 Microclean/66 HRC) and the high speed steel HS 6-5-3 PM (S790 Microclean/64 HRC). The milling tests were performed at effective cutting speeds of 225, 300, and 400 m/min with a four fluted solid carbide ball-end mill ( = 6, TiAlN coating). It was observed that by means of analytically optimised chipping parameters and increased cutting speed, the tool life can be drastically enhanced. Further, in machining the harder material HS 4-2-4 PM, the tool life is up to three times in regard to the less harder material HS 6-5-3 PM. Thus, it can be assumed that not only the hardness of the material to be machined plays a vital role for the high-speed dry-hard cutting performance, but also the microstructure and thermal characteristics of the investigated powder metallurgical steels in their hardened state.

Tool Wear in High-Speed Milling of Ti-6Al-4V Alloy

Titanium alloys are widely used in the aerospace industry for applications requiring high strength at elevated temperature and high mechanical resistance. However, titanium alloys are classified as extremely difficult-to-cut materials owing to their physical, chemical, and mechanical properties, which result in the low material removal rate and the short tool life. This paper presents an experimental research of the tool wear patterns and relevant wear mechanisms during high-speed milling of Ti-6Al-4V with cemented carbide inserts. SEM-EDX analysis showed that nose wear and edge wear were the main tool failure modes during high-speed milling process, which were different from the wear patterns under traditional cutting conditions. Adhesion, attrition and diffusion wear mechanisms, as well as the cracks were responsible for the tool wear.

An investigation of the influence of sulphide inclusions on tool-wear in high speed milling of tool steels

Experimental results have shown that the machinability of tool steels, in term of tool-life, is increased with sulphides addition. It seems that this increase depends on cutting speed, probably due to the existence of an adherent layer of manganese sulphides (MnS) frequently observed in turning. Previous studies on the same materials have shown that at high cutting speeds, the action of sulphur disappears. The choice of the best cutting parameters is presented in detail according to the tool-work material pair method. Experimental design has been used to determine the tool-wear rate and to discuss the effect of each influencing factor and interaction. During the progressive tool-wear, rake face investigations to study the influence of sulphide inclusions have been performed using scanning electron microscopy (SEM) techniques.