Tool Wear Influence on Surface Integrity and Fatigue Life of Hard Milled Surfaces

Author(s):  
W. Li ◽  
Y. B. Guo ◽  
M. E. Barkey

In machining, the interfacial friction between cutting tool and work material leads to tool wear which is considered a critical factor for surface quality of machined components. Surface integrity and fatigue life of machined components will deteriorate when tool flank wear progresses in machining. Hard milling experiments on AISI H13 tool steel (50 ± 1 HRC) using PVD coated tools with different levels of flank wear were conducted in this study. Surface integrity of the machined components with flank wear VB = 0 mm, 0.1 mm and 0.2 mm was characterized. The effects of cutting speed, feed, and radial depth-of-cut on surface integrity were investigated respectively at the three levels of tool flank wear. In addition, four-point bending fatigue tests were performed on the milled samples at five levels of different flank wear (VB = 0, 0.05, 0.10, 0.15, 0.20 mm) to evaluate the trend of fatigue life evolution with the increased tool flank wear.

Author(s):  
W. Li ◽  
Y. B. Guo ◽  
M. E. Barkey ◽  
C. Guo ◽  
Z. Q. Liu

Tool flank wear during hard milling adversely affects surface integrity and, therefore, fatigue strength of machined components. Surface integrity and machining accuracy deteriorate when tool wear progresses. In this paper, surface integrity and its impact on endurance limit of AISI H13 tool steel (50 ± 1 HRC) by milling using PVD coated tools are studied. The evolutions of surface integrity including surface roughness, microhardness and microstructure were characterized at three levels of tool flank wear (VB = 0, 0.1mm, 0.2mm). At each level of tool flank wear, the effects of cutting speed, feed, and radial depth-of-cut on surface integrity were investigated respectively. Fatigue endurance limits of the machined surfaces at different reliability levels were calculated and correlated with the experimentally determined fatigue life. The good surface finish and significant strain-hardening on the machined surfaces enhance endurance limit, which enables machined components have a fatigue life over 106 cycles.


Author(s):  
W. Li ◽  
Y. B. Guo

Interfacial friction between cutting tool and work material leads to tool wear during machining, which adversely affects surface integrity of machined components. In addition, more energy is expected to be consumed to accommodate higher loading during machining. Dimensional accuracy and repeatability of the workpiece is also hard to guarantee when machining with worn tools. In this paper, surface integrity of AISI H13 samples milled using the PVD coated inserts is studied. Three levels of tool flank wear (VB = 0, 0.1mm, 0.2mm) were used to cut H13 tool steel in the experiment. At each level of flank wear, the effects of cutting speed, feed, and radial depth-of-cut on surface integrity were investigated respectively. Under a diverse combination of milling parameters, the evolution of surface integrity with tool flank wear was analyzed. A novel on-line optical tool inspection system integrated with CNC machining center was used to inspect the evolution of flank wear with milling time in order to monitor tool wear conditions.


2017 ◽  
Vol 882 ◽  
pp. 36-40
Author(s):  
Salah Gariani ◽  
Islam Shyha ◽  
Connor Jackson ◽  
Fawad Inam

This paper details experimental results when turning Ti-6Al-4V using water-miscible vegetable oil-based cutting fluid. The effects of coolant concentration and working conditions on tool flank wear and tool life were evaluated. L27 fractional factorial Taguchi array was employed. Tool wear (VBB) ranged between 28.8 and 110 µm. The study concluded that a combination of VOs based cutting fluid concentration (10%), low cutting speed (58 m/min), feed rate (0.1mm/rev) and depth of cut (0.75mm) is necessary to minimise VBB. Additionally, it is noted that tool wear was significantly affected by cutting speeds. ANOVA results showed that the cutting fluid concentration is statistically insignificant on tool flank wear. A notable increase in tool life (TL) was recorded when a lower cutting speed was used.


2011 ◽  
Vol 188 ◽  
pp. 410-415 ◽  
Author(s):  
Yuan Wei Wang ◽  
Jian Feng Li ◽  
Z.M. Li ◽  
Tong Chao Ding ◽  
Song Zhang

In this paper, some experiments were conducted to investigate tool wear when end-milling Inconel 718 with the TiAlN-TiN PVD coated carbide inserts. The worn tools were examined thoroughly under scanning electron microscope (SEM) with Energy Dispersive X-ray Spectroscopy and 3D digital microscope to expatiate tool wear morphologies and relevant mechanisms. The flank wear was uniformity in finishing milling process, and the average flank wear were selected as the criterion to study the effects of cutting parameters (cutting speed, feed per tooth, radial depth of cut, and axial depth of cut) on tool wear. Finally, the optimal combination of the cutting parameters for the desired tool life is obtained.


2006 ◽  
Vol 315-316 ◽  
pp. 588-592 ◽  
Author(s):  
Wei Zhao ◽  
Ning He ◽  
Liang Li ◽  
Z.L. Man

High speed milling experiments using nitrogen-oil-mist as cutting medium were undertaken to investigate the characteristics of tool wear for Ti-6Al-4V Alloy, a kind of important and commonly used titanium alloy in the aerospace and automobile industries. Uncoated carbide tools have been applied in the experiments. The cutting speed was 300 m/min. The axial depth of cut and the radial depth of cut were kept constant at 5.0 mm and 1.0 mm, respectively. The feed per tooth was 0.1 mm/z. Optical and scanning electron microscopes have been utilized to determine the wear mechanisms of the cutting tools, and energy spectrum analysis has been carried out to measure the elements distribution at the worn areas. Meanwhile, comparisons were made to discuss the influence of different cutting media such as nitrogen-oil-mist and air-oil–mist upon the tool wear. The results of this investigation indicate that the tool life in nitrogen-oil-mist is significantly longer than that in air-oil-mist, and nitrogen-oil-mist is more suitable for high speed milling of Ti-6Al-4V alloy than air-oil-mist.


2010 ◽  
Vol 26-28 ◽  
pp. 1052-1055
Author(s):  
Li Fa Han ◽  
Sheng Guan Qu

The wear characteristics and life of Al2O3/(W,Ti)C ceramic tool in turning NbCp-reinforced iron-based P/M composites was investigated. Experimental results indicate that cutting parameters have an influence on tool wear, among which cutting speed and depth of cut seem to be more prominent. The maximum flank wear rapidly increases as the increase in cutting speed and depth of cut. While, it increases gradually as the decrease in feed rate. Meanwhile, an empirical model of tool life is established, from which the influence of cutting speed and depth of cut on tool life is far greater than that of feed rate. Also from the empirical model, the preferable range of cutting parameters was obtained.


2014 ◽  
Vol 699 ◽  
pp. 64-69 ◽  
Author(s):  
A.B. Mohd Hadzley ◽  
A. Siti Sarah ◽  
R. Izamshah ◽  
M.R. Nurul Fatin

The increasing productivity demand in machining industry has lead for fast material removal machining technique of pocket milling using different tool path strategies. This project aims to study about the effect of different tool path strategies on tool wear when machining aluminium alloy 7076. Five milling strategies were evaluated outward helical, inward helical, back and forth, offset on part one-way and offset on part zigzag. CATIA V5R19 was used to setup milling path and the machining experiments were carried out on a HAAS’ 3 axis CNC milling machine. The machining was held under wet condition with 2500 rpm cutting speed, 800 mm/min feed rate, 2 mm radial depth of cut and 2 mm axial depth of cut. The results showed that the best tool path strategies are inward helical and offset on part one-way, while the worst tool path strategy is outward helical. Failure to evacuate chip during pocket milling is the main reason to cause rapid tool wear due to temperature rise and higher contact time and area of cutting tool with the chip. Results from this experiment help to guide the machinist to perform pocket milling effectively.


Author(s):  
Y. B. Guo ◽  
Jie Sun

End milling titanium Ti-6Al-4V has wide applications in aerospace, biomedical, and chemical industries. However, milling induced surface integrity has received little attention. In this study, a series of end milling experiment were conducted to comprehensively characterize surface integrity at various milling conditions. The experimental results have shown that the milled surface shows the anisotropic nature with a surface roughness range in 0.6 μm–1.2 μm. Surface roughness increases with feed and radial depth-of-cut (DoC), but varies with the cutting speed range. Compressive residual normal stress occurs in both cutting and feed directions, while the influences of cutting speed and feed on residual stress trend are quit different. The microstructure analysis shows that β phase becomes much smaller and severely deformed in the very near surface with the cutting speed. The milled surfaces are at least 60% harder than the bulk material in the subsurface.


2015 ◽  
Vol 1115 ◽  
pp. 100-103
Author(s):  
A.K.M. Nurul Amin ◽  
Muammer Din Arif ◽  
Siti Aminatuzzuhriyah B. Haji Subir ◽  
Fawaz Mohsen Abdullah

Chatter is a type of intensive self-excited vibration commonly encountered in machining. It reduces productivity and precision, and is more noticeable in the machining of difficult-to-cut alloys like hardened steel. In such cases chatter causes excessive tool wear, especially flank wear, which in turn affects the stability of the cutting edge leading to premature tool failure, poor surface finish, and unsatisfactory machining performance. Nowadays, however, the demand is for fine finish, high accuracy, and low operation costs. Therefore, any technique which significantly reduces chatter is profitable for the industry. This paper demonstrates the viability and effectiveness of a novel chatter control strategy in the turning of (AISI 304) stainless steel by using permanent bar magnets. Reduction in chatter and corresponding tool flank wear are compared from results for both undamped and magnetically damped turning using coated carbide inserts. Special fixtures and keyway were made from mild steel in order to affix the magnets on the lathe’s carriage. The two ferrite magnets (1500 Gauss each) were placed below and beside the tool shank for damping from Z and X directions, respectively. Response surface methodology (RSM) was used to design the experimental runs in terms of the three primary cutting parameters: cutting speed, feed, and depth of cut. A Kistler 50g accelerometer measured the vibrations. The data was subsequently processed using DasyLab (version 6) software. The tool wear was measured using scanning electron microscope (SEM). Results indicate that this damping setup can reduce vibration amplitude by 47.36% and tool wear by 63.85%, on average. Thus, this technique is a simple and economical way of lowering vibration and tool wear in the turning of stainless steel.


2011 ◽  
Vol 188 ◽  
pp. 78-83
Author(s):  
Xin Qiang Zhuang ◽  
Chuan Zhen Huang ◽  
Zi Ye Liu ◽  
Bin Zou ◽  
H.L. Liu ◽  
...  

The milling experiments of the annealed T10A steel were carried out in the various cutting conditions using the coated cemented carbide tool. The cutting parameters were designed by the multi-factor orthogonal experiment method, and the effects of cutting speed, feed, axial depth of cut and radial depth of cut on the cutting force and tool wear were investigated. The tool wear mechanisms were also discussed. Adhesion, abrasion, diffusion and oxidation were the main tool wear mechanisms. According to these investigations, the optimizing cutting parameter was recommended.


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