Papers by Keyword: Cemented Carbide

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Authors: Jian Wu Yu, M. Cheng, Shao Hui Yin, G.Z. Xie, X.L. Zhou
Abstract: The machining characteristics of cemented carbide YG8 under high speed grinding conditions are reported in this paper. The experimental investigation focused on the grinding force, surface roughness and surface characteristics influenced by various wheel speeds, feed rates and depths of cut. Surface roughness was slightly improved by increasing of wheel speed, and the increase in hmax generated bigger grinding force and decreased specific energy, which could be explained by material removal mode and SEM micrographs of surface. The results revealed that high machining efficiency was achieved and relatively good surface roughness was obtained simultaneously.
Authors: Hoo Soon Im, Jah Mahn Hur, Wan Jae Lee
Abstract: The dry-milling technique was used for mixing and crushing oxides and graphite powder to get homogeneous mixed powders. The weight ratio of ball-to-powder was 30:1 and argon gas was filled in jar. The carbon content was more 10~ 20wt% than the stoichiometric amount. The drymilling was carried for 20 hours. After milling, the mixed powders were reduced and carburized at 900~980°C for 3 hours flowing Ar gas in tube furnace. The dry-milled powders showed wide diffraction patterns of X-ray. The reactions of reduction and carburization were completed in 3 hours at 980°C. After the reactions, the mean size of WC particles was about 200 nm. The content of free carbon in WC/Co mixed powders decreased as the reaction temperature increased.
Authors: Lin Zhu, Jiang Ping Wang
Abstract: Focusing on the difficult-to-cut characteristic of titanium alloy, this paper selects several cemented carbide tool materials in the tests of machining the titanium alloy workpieces. Different sets of geometrical parameters of the drilling bits are grouped, chosen and optimized, and then deep-hole drilling tests are carried out. The suitable cutter materials and the optimum geometrical parameters of the cutter for drilling deep holes in titanium alloy have been determined through the analysis of tested results.
Authors: Rosemar Batista da Silva, Márcio Bacci da Silva, Wisley Falco Sales, Emanuel Okechukwu Ezugwu, Álisson Rocha Machado
Abstract: Machining efficiency of titanium alloys is crucial to the aerospace industry especially in the manufacture of bladed discs (blisks) where over 80% of titanium alloy material is roughed out to generate the complex shapes and contours of components. The choice of the right tool materials for machining titanium alloys contributes enormously to reducing the overall machining time by significantly lowering the cycle time and indexing of the cutting edges. These improvements lead to a reduction of the manufacturing cost by up to 30%. Uncoated and coated carbide tools have demonstrated encouraging performances when turning Ti-6Al-4V alloy, especially under roughing operations complemented by high pressure cooling technology, at high cutting speed and depth of cut conditions that increase the metal removal rate. Under such cutting conditions there is no significant difference in performance between coated or uncoated carbide tools when turning Ti-6Al-4V alloy. Super abrasives like ceramics and cubic boron nitride (CBN) tools are not suitable for machining titanium alloys as low tool life with no economic benefit is achieved because of severe chipping and fracture of the cutting edge. Machined surfaces produced with ceramic tools have very low surface integrity status because of loss of form as a result of accelerated tool wear and the consequent chipping and fracture encountered during machining. Polycrystalline diamond (PCD) tools are suitable for finish turning Ti-6Al-4V alloy at cutting speeds up to 250 m/min.
Authors: Xiong Yang, Xiao Ming Li, Jian Tong
Abstract: This paper researches the influences of different peak currents, gap voltages, pulse widths and duty cycles on the electrode relative depletion rate about EDM of YG11. It also makes the comparison graphs of different electrodes for analyzing and provides the experimental basis for electrode material optimization of cemented carbide EDM.
Authors: A. Ottlik, Volker Schulze, L. Pintschovius, Hermann Müller, Detlef Löhe
Abstract: Brazing of cemented carbides to steel bodies gives rise to the development of complex stress states and distortions which influence the fatigue behaviour of the parts. It is quite important to estimate the residual stresses with numerical methods whose agreement is to be guaranteed with experimental characterization of the brazed parts. In this work FEM simulations and X-ray as well as neutron stress analysis were used to examine the residual stresses of brazed samples. Joints with different geometries and dimensions made of cemented carbide and different steels showing different phase transformation behaviours were investigated.
Authors: Marcelo Bertolete, Izabel Fernanda Machado, Daniel Rodrigues
Abstract: The aim is to analyze the influence of two sintering process parameters concerning the compact densification of WC-Co. The input variables studied were uniaxial pressure (40 and 60 MPa) and holding time (1 and 3 minutes). The output variables monitored were relative density, microstructural features, besides online monitoring of dynamics of sintering. The samples were sintered in a Dr. Sinter-Syntex machine of Spark Plasma Sintering (SPS), which allows heating rate greater than conventional sintering techniques, with the advantage of lower temperature, time and energy consumption. The powder used was a compaction residue of grade K (with content between 3 and 12%Co). The results showed significant influence of pressure on the density and percentage of the porous area; however, the process parameters did not affect the grain size.
Authors: Li Liu, Yao Nan Cheng, Jun Qian, Ya Nan Gong, Ming Yang Wu, Fu Gang Yan
Abstract: In the machining process of large parts, the dynamic alternating loading suffered by heavy carbide insert is very large, so the fatigue failure of the insert is serious. Through the analysis the effect of dynamic alternating force - thermal load on insert’s crack, and the fatigue crack experiment of inserts under dynamic alternating loading will be done, the formation conditions and distribution law of fatigue cracks can be researched under the effect of dynamic mechanical shock and thermal shock. And the fatigue crack will be theoretical analysis through the fatigue curve in the range of test cutting parameters. It can provide effective basis for the optimizing the heavy-duty cutting parameters and reducing the fatigue crack failure of heavy-duty cutting insert.
Authors: Qiu Lin Niu, Qing Long An, Ming Chen, Gang Liu, Cheng Yong Wang
Abstract: The cryogenic treatment is an extension of the cold processing technology by which the material properties could be changed. This provides a new method for people to improving the performance of the cutting tools and prolonging the tool life. The micro-structure of two unknown types of carbide reamers after different cryogenic treatment was introduced in this paper. From the metallographic microstructure, SEM microstructure, EDS spectrum analysis and the hardness measurement, the detailed analysis on the microstructure of the reamers (1# and 2#) was provided in this paper. The results show that the matrix materials of the two reamers were the WC-Co cemented carbide, and they were the ultra-fine grain carbide (<500nm); 2# reamer belonged to the high Co cemented carbide reamer. By the cryogenic treatment, the hardness of two reamers has increased. And the value of the hardness for 1# reamer was higher than that for 2#.
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