Papers by Keyword: Hard Material

Abstract: Engineering ceramics have received significant attention in the recent years owing to their exceptional mechanical properties, which are expected to be beneficial for engineering applications. However, it has always been a great challenge to realize ductile-mode grinding in engineering ceramics, with one of the critical obstacles being the heat generation that limits the removal rate. As a result, thermal damages are often observed on the ground surfaces. This paper presents the ductile-mode grinding. In the process the grinding wheel is excited along the radial direction by applying an ultrasonic vibration of frequency is 38.5 kHz and amplitude of 0-2 μm. The wheel comes in contact with the Al₂O₃ ceramic at constant forces 18-24 N. Experimental results indicate that the ground surface is devoid of thermal damages, when removal rate of the vibration-assisted process is approximately 1.5 times higher than without vibration.Keywords: ductile-mode grinding, radial directional vibration, hard and brittle material, engineering ceramic, thermal damage

Abstract: In this study, two different arrangement lapping disks fixed with brazed diamond pellets were used to lap silicon wafer and alumina ceramic. The effects of the surface morphology, roughness, and removal rate of workpiece caused by lapping pressure, lapping time, workpiece velocity, and disc arrangement were operated with serials experiments. The results of the researches provided guidance for fixed abrasive lapping of hard and brittle materials with the brazed micro powder diamond disk.

Abstract: Rotary ultrasonic machining(RUM) as a precise and efficient processing method for hard and brittle materials can be used for significantly improving processing efficiency, reducing the cutting force and cutting heat, improving the surface quality. Development of high performance RUM machine tools and equipments has been caused on widespread attention from the worldwide scholars. In this paper, the development of the RUM machine tools has been reviewed about the accessory RUM head and load matching system.

Abstract: Recently, in accordance with the technical development and miniaturization of the information equipments, the demand of optic elements with high precision and miniaturization is increased. The mold is used in the manufacture of the optic elements. Thus, it is needed to machine the mold with high efficiency and high precision. As the material of mold, hard material including cemented carbide and ceramics is used. However, it is a problem of the occurrence of severe tool wear when hard material is machined. To solve this problem, the cutting point swivel machining by using the diamond tool with special chamfer was proposed, which has the ability to suppress tool wear and to realize ultraprecise machining. It is confirmed that the cutting point swivel machining has the ability to suppress tool wear by the microgrooving experiment of SiC. This study aims at investigating the effect of the cutting point swivel machining, and making clear the relationship between tool rotation speed and tool wear. As a result, it is known that the actual cutting direction can be changed by using the cutting point swivel machining, and that the chipping of tool becomes conspicuous with increasing tool rotation speed.

Abstract: Hard materials based on Alumina (AN), Silicon Carbide (SC), Boron Carbide/Nitride (BC/N), Zirconia (ZN), and alike are often used to produce abrasive grains and coat cutting tools. These materials improve the performance of grinding/machining operations by providing an enhanced productivity, a longer grinder/tool life, and a better surface finish. On the other hand, they might leave some burdens on the environment. Therefore, eco-attributes (i.e., energy consumption, CO₂ emission, NO_X/SO_X emission, water usage, recycle fraction, etc.) of these hard materials should be used to make an informed decision. This study deals with this issue and provides an evaluation of AN, SC, BC/N, and ZN based hard materials in terms of CO₂ emission, NO_X emission, SO_X emission, and water usage. The outcomes of this study are useful for analyzing grinding and other abrasive processes for achieving eco-manufacturing.

Abstract: A novel adaptive force control table for rotary ultrasonic machine tool was developed for processing micro holes. The adaptive force control table, a mechanical balancing device by which the load can be adaptively adjusted without numerical control was adopted as an attachment in an ultrasonic machine tool. To verify the performance, micro holes were drilled on SiC workpiece. The drilling force, tool wear and profiles of these machined micro holes were investigated. According to the experimental results, it is confirmed that the newly developed table attached on the ultrasonic machine tool is an economical and efficient approach for machining micro holes on hard and brittle materials.

Abstract: In order to deeply study the influence of ultrasonic assistance on material removal characteristics of hard and brittle materials, a series of ultrasonic assisted single-point scratch experiments have been carried out in this paper. Experimental results show that the assisted ultrasonic vibration is benefit to increase the critical cutting depth and enlarge the ductile regime of material removal. The main reason can be explained as the influences of blank cutting phenomenon, the decrease of the normal cutting force under the same depth of cut, the decrease of the material hardness under ultrasonic excitation and the shielding effect of lateral crack.

Abstract: In this work a factorial planning had been used to evaluate the CBN tool life during cut-ting SAE 8620 steel. Part U2222 of a TPGW 160408 insert of TX-LS TB650 and 2NU-SHMA6942 S7182BN300 classes from two manufacturers were used in this experiment. A 23 factorial design was used In cutting process to evaluate the behavior of the tool life and reason of the exchange of the part on influences of the chamfer (in S and T+S), the advancing speeds (0.09, 0.10 and 0.11 mm/rpm) at a cutting speed of 91.2 m/min. Model have been fit by variance analysis (ANOVA) and the processing optimization was done by response surface methodology (RSM). Results showed that a hyperbolic model had more adjusting than other models and the optimization showed a high life time for the TX-LS TB650 tool from A manufacturer on 0.09 mm/rpm of advancing speed, where it was observed that the pre-cranking was the reason of the exchange.

Abstract: For machining of hard and brittle materials, iron electrodeposit is a kind of matrix material with potential advantages for manufacture of diamond tools. Aiming at the problem of difficult codeposition of diamond in iron deposit, this paper adopts orthogonal design of experiment to study the effects of solution pH value, cathodic current density, alkylphenol polyoxyethylene (10) ether (OP-10) concentration and ammonium chloride concentration on codeposition of diamond, and then Fe-based diamond bits were fabricated and drilling tests in granite were carried out. The results show that pH value, cathodic current density, OP-10 concentration and ammonium chloride concentration all have statistically significant effect on codeposition of diamond in iron deposit, whose contributions to the variance of the weight of codeposited diamond are 37.45%, 32.05%, 13.13% and 12.38%, respectively. The result of drilling test indicates that Fe-based diamond bit can achieve much higher penetration rate than common Ni-based diamond bit.

Abstract: Recently, in accordance with the technical development and miniaturization of the information equipments, the demand of optic elements with high precision and miniaturization is increased. The die is used for manufacturing the optic elements. Thus, it is needed to machine the die with high efficiency and high precision. As the material of die, hard material including cemented carbide and ceramics is used. However, when hard material is machined, there is a problem that severe tool wear occurs, and worn tool shape is transferred into the surface so that precision machining cannot be realized. In this study, a method, called cutting point swivel machining, is proposed to suppress tool wear by using the tool with special chamfer and all parts of tool tip. The effect of tool wear suppression is verified by the machining of SiC. Then, the relation between the suppression of tool wear and tool rotation period is verified.