Papers by Keyword: Tool Life

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Authors: Jian Bing Cheng, Si Qin Pang, Xi Bin Wang, Qi Xun Yu
Abstract: Ultrafine WC-Co cemented carbide cutting inserts were prepared by direct low pressure sintering and low pressure sintering after the powder pretreatment, tool life tests of continuous cutting superalloy GH2132 were carried out, respectively. ZEISS continuous zoom stereo microscope and microphotograph system were used to observe flank surface wear morphology of the cutting inserts, and analysis the topography and elements of central wear region of flank surface by X-ray energy dispersive spectrometry and scanning electron microscope. The results show that the main wear mechanism of ultrafine cemented carbide cutting inserts is adhesive wear, and the wear resistance of ultrafine cemented carbide cutting inserts that low pressure sintering after powder pretreatment is superior to direct sintering, powder pretreatment helps increase the resistance of abrasive wear, adhesive wear and oxidative wear as well as diffusive wear of cutting inserts.
Authors: Akihiro Minami, Yoshihiro Tabaru, Yasuo Marumo, Li Qun Ruan, Hiroyuki Saiki
Abstract: Tool damages including plastic deformation and wear are affected by forging load, thermal load and frictional slide applied to tool surface. Plastic deformation of forging tools proceeds in the tool corer owing to elevated temperature, high contact pressure and severe frictional slide. Hard layers on the tool surface increase plastic deformation resistance and thermal resistance. The optimal design of hard layer structure reduces the tool damage and improves tool life. Temperature and equivalent strain of forging tools are influenced by friction shear factor, contact thermal conductance and contact time between the tool and the workpiece. At the friction shear factor of less than 0.4, equivalent strain of the tool is reduced. At the friction shear factor of approximately 0.4 or greater, equivalent strain increases sharply and concentrates in the vicinity of the surface hard layer. This tendency becomes more significant when the contact time between the tool and the workpiece increases. Equivalent strain is reduced by low workpiece temperature.
Authors: Ali Davoudinejad, Sina Alizadeh Ashrafi, Abdolkarim Niazi
Abstract: Aluminum 6061 is a common alloy which is widely used in aerospace and yacht construction industry. Generally machining of aluminum alloys inherently generates high chip sticking on tool face and changes the tool edge geometry, which not only reduces tool life but also impairs the product surface quality. This study investigated the tool life and tool wear mechanisms besides evaluating surface roughness in various cutting conditions to attain finest possible surface with minimum tool wear. Turning experiments performed under dry orthogonal cutting of Al6061 using carbide CVD tri-phase coated inserts with constant depth of cut, various cutting speeds and feed rates. Insert’s flank and rake faces analyzed to assess wear mechanisms. Additionally Scanning electron microscope (SEM) employed to clarify different types of wear. Surface integrity and effect of built up edge in deviating surface roughness were studied in each cutting condition. Additionally results of experiments demonstrated that built up edge took over cutting edge and with sacrificing surface roughness, tool life increased by decreasing pace of abrasive wear propagation on flank face. According to these experiments the main reasons of flank wear were abrasive and adhesion of aluminum on tool face.
Authors: Michio Uneda, Naoki Takahashi, Yutaro Arai, Takashi Fujita
Abstract: Chemical mechanical polishing/ planarization (CMP) is a key technology for fabricating high-efficient semiconductor devices, and the CMP characteristics (removal rate and accuracy, etc.) is depended on the various consumables represented by slurry, polishing pad and dresser used in the CMP process. Currently, in the pad, there are many studies that have pointed the evaluation methodology and the correlation between the pad surface asperity and the CMP characteristics. On the other hand, the dresser is one of the most important consumables because the dresser can control the pad surface asperity, and the diamond grains electrodeposited dresser (diamond dresser) is frequently used. One drawback point of the diamond dresser is that the dressing performance declines owing to the deterioration of the diamond grains. Previously, we have developed a novel flexible fiber dresser that would ensure high performance and longer life of tools, and we have reported the fundamental characteristics by the flexible fiber dresser compared with that of the diamond dresser. In this paper, we will show the results of tool life evaluation of the flexible fiber dresser using a contact image analysis method. As a result, the flexible fiber dresser can be continuously used over 35 hours. Furthermore, the result of having examined the stability of the removal rate of a silicon wafer is reported. Therefore, we found that the flexible fiber dresser is one of the most effective dressing methods for the polishing pad.
Authors: AKM Nurul Amin, Mohammad Ishtiyaq Hossain, Anayet Ullah Patwari
Abstract: Abstract. This paper presents the outcome of a study on heat assisted end milling of Inconel 718 using inducting heating technique conducted to enhance the machinability of the material. The heating temperature maintained below the phase transformation temperature was aimed at softening the top removable material layers. The experimental results of both conventional and heat assisted machining were compared. The machinability of Inconel 718 under these conditions was evaluated in terms of tool life, tool wear morphology and chatter. The advantages of Induction heating is demonstrated by an longer tool life and lower chatter. The study showed that preheated machining facilitates up to 80% increase of tool life over conventional machining conducted using TiAlN coated carbide inserts.
Authors: Claudiu Ioan Jugrestan, Marcel Sabin Popa, Stefan Sattel, Dan Preja, Ovidiu Virgil Vereș, Elena Adina Cotargă
Abstract: In this paper are presented and analyzed a series of problems that are appearing during the CFRP machining. Due to their properties, the composite materials began to replace traditional materials (ferrous and non-ferrous) in a lot of industries leading out the development of new methods of machining or adaptation of the classic. Unlike traditional material, drilling in CFRP is more difficult due to inhomogeneity of the material, its high hardness but also due to lack of knowledge relating to how these materials behave. This paper investigates different types of tool wears as corner wear, welding, crater wear that are appearing in drilling operation due to the highly abrasive nature of the carbon fibers. Also, here is presented an evaluation that refers to the machined hole quality and describe defects as delamination, pull outs, fibers projections, pyrolysis and shape errors. The main goal of this paper is to verify the current status of technique in CFRP drilling in order to develop and produce a new drill geometry in a cooperation between the Technical University of Cluj-Napoca and the cutting tool company Gühring KG.
Authors: Qi Shi, Yin Fei Yang, Ning He, Liang Li, Wei Zhao
Abstract: TC4-DT is a new damage-tolerant titanium alloy. In the paper, a series of experiments on tool wear and surface integrity in high speed milling of the alloy were carried out. The tool lives of different tool materials were studied and the wear mechanism of cutting tools was also investigated. Then surface integrity, including surface roughness, microhardness and metallurgical structure was studied and analyzed in high speed milling at different tool wear status. Results showed that K10 is the most suitable cutting tool after considering a combination of factors. And good surface integrity could be obtained in high speed milling of TC4-DT under all cutting situations. In addition, even with acutely worn stages, there has been no so-called serious hardening layer (or white layer) according to the study of microhardness and metallurgical structure beneath the machined surface.
Authors: Fei Hu Zhang, J.C. Gui, Yi Zhi Liu, Hua Li Zhang
Abstract: Nano cemented carbide is a new style cutter material. Because its grain size is very small, it is superior to common cemented carbide in properties, such as high hardness, fracture toughness, flexural strength and higher abrasion resistance. As a cutter material, nano cemented carbide has wide use. In this paper, nano cemented carbide tool was ground with ELID technology, and the cutting properties of nano cemented carbide were studied, and the difference in cutting properties among the ultra-fine grain, common cemented carbide and nano cemented carbide was analyzed under the same condition. Results imply that the ground surface roughness of nano cemented carbide is obviously lower than that of common cemented carbide, and the tool life of nano cemented carbide is 5-7 times longer than that of common cemented carbide at low cutting speed.
Authors: Xin Liu, Wen Ji Xu, Jing Sun
Abstract: Dry electrostatic cooling (DESC) assisted machining is one of the green machining technologies that uses ionized air flow as lubricating and cooling medium in the machining process. The influence of discharge parameters on the efficiency of ion transport and ozone concentration in the DESC is experimentally researched. The results show that the efficiency of ion transport increases with the rising of the discharge current and air pressure, but decreases with the rising of the distance from the nozzle and the nozzle diameter. The tungsten electrode is used to obtain high ozone concentration with the nozzle diameter of 2-4mm, air pressure of 0.2-0.4MPa, and the distance from the nozzle within 0.5mm. Experimental research on the DESC assisted machining for hardened steel GCr15 shows that cutting force decreases by 7%-28%, tool wear reduces by 30-50%, and tool life is 1.5-3.3 times more than dry cutting. Better results are achieved when increasing the cutting speed.
Authors: Shu Bao Yang, Jiu Hua Xu, Yu Can Fu, Guo Hui Zhu
Abstract: Milling tests were undertaken to analyze and compare the machinability of hydrogenated titanium alloy Ti6Al4V. Uncoated WC-Co tool inserts were used in the study. The feed and the depth of milling were maintained constant, and only the milling speed was varied because it is the most affecting parameter. Results showed that cutting force and tool life were greatly influenced by the contents of hydrogen. Tool life decreased at first and then increased gradually with the increase of hydrogen content, and the maximum magnitude decrease of tool life is about 0.2%H, meanwhile, the maximum tool life is about 0.5%H. However, with the increase of cutting speed, the favorable effect of hydrogen on the titanium alloy machinability would be weakened even disappear, therefore, 50-100m/min would be a suitable choice of cutting speed.
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