Papers by Keyword: Lapping

Abstract: The water soluble grinding fluids (coolants) with 3M^TM Trizact^TM Diamond Tile（TDT）used in thinning process of the flat glass contains lubricants, extreme pressure antiwear agents, surfactants and anti-rust additives, which are expected to provide the functions of lubricating, cooling, cleaning, anti-rust. The results showed that the water soluble grinding fluids can improve the processing performance of 3M TDT effectively, keep excellent self-sharpening, increase processing efficiency, extend the service life of the abrasive pads and reduce surface roughness of the glass .

Abstract: An ultra-precision lapping machine is developed, with precision turning technology to condition lapping plate in situ, pressurizating by cylinder pressure, and cooling frictional heat with inner cooling system, the lapping machine is used for ultra-precision lapping of brittle materials. The design concept and the structure of the key components of the utra-precision sngle-plane lpping mchine are discussed. After precision turning, the flatness of lapping plate is down to 0.002 mm/400 mm, and experimental results show that the flatness of circular grating glass has been greatly improved after ultra-precison lapping.

Abstract: Optimisation of technological processes is an important field of research of machining processes. Honing process, its aim and results are affected more factors. Effectiveness is expressed by the following parameters: accuracy, surface roughness, complex surface quality (integrity),material removal rate, costs and productivity of the process. Developed method helps the technology planning and with the introduced new goodness indicator, investigates and corrects it. Optimization and minimization of costs can be ensured at given technological circumstances and technological parameters. With adjustment of the pressure (p) and the cutting speed (v_c) economy of the process can be increased in the factory. Developed method can be applied for machining by other abrasive cutting tools. The paper summarizes new results of this theoretical and experimental research.

Abstract: The machining methods such as waterjet cutting, milling, grinding, lapping, etc. are usually used to manufacture glass fiber reinforced composites (GFRCs) parts. Damages will be produced unavoidably in the machining process, no matter which machining method is employed. Subsurface damage is one of the important parameters to evaluate the surface layer damages. The detection method for the subsurface damages of glass fiber reinforced glass matrix (glass/glass) composite after machining is researched. The characteristics of subsurface damages of glass/glass composite after waterjet cutting, milling, grinding and lapping are investigated mainly, when the fiber direction is either perpendicular or parallel to the cutting surface.

Abstract: This paper is to design and developing a friction sensor system (FSS) for prediction of endpoint detection (EPD) on diamond lapping of sapphire or mono-crystalline aluminum oxide wafers. The endpoint detection usually includes start region, lapping region, transient region and endpoint region to control the planarization procedure by diamond lapping with variant plate of copper, resin copper, or tin materials. Experiments have been performed with 9 tests composed by three kinds of viscosity of slurry lapping with three kinds of lap plates. The coefficient of friction (CoF) has been obtained by the designed FSS and then compared with different test parameters. The as-lapped sapphire wafers have also measured by coherence surface interferometer, CCI-Lite (Taylor Hobson, UK). Experimental results show that the hardness of plate and viscosity of slurry are critical factors for as-lapped wafer quality. The EPD of diamond lapping with resin copper plate can be determined by the CoF data and that can be used for justifying the appropriate lapping time of sapphire wafers. Future study can focus on the relationship of sub-surface crack caused by the diamond lapping process.

Abstract: In order to remove the cutting marks on the cutting surface of 6H-SiC single crystal wafer, experiments were conducted to investigate the effect of the abrasive characteristics (types, grain size, concentration and mixed abrasives) on the lapping performance of 6H-SiC single crystal wafer, then the removal mechanism of the abrasive grains in the lapping process was studied. Results indicate that the abrasives with larger grain size and higher hardness can result in a higher material removal rate while the abrasives with smaller grain size and lower hardness can achieve a lower surface roughness value. When the concentration of the abrasives is 7.69 wt%, a good lapping effect was obtained. Lower surface roughness value Ra can be obtained with a high material removal rate by using certain proportion mixed abrasives. Selecting appropriate abrasives can obtain a high surface quality of 6H-SiC wafer with a high efficiency.

Abstract: This paper will present the results of research on single-disc lapping of flat surfaces of small ceramic elements. Machining with the use of different tools such as metallic, two-metallic and abrasive-metallic will be analyzed. The basics and techniques of reinforcement of laps will be discussed. The results of the influence of parameters on the surface quality of ceramic conponents (sealing0 for three treatments on lapping machines will be presented on the paper.

Abstract: Lapping leads to a surface with low roughness and high precision. Because of required parts accuracy tool flatness is the key to the successful machining. To avoid its excessive thermal expansion, plate temperature research was taken. The goal was to determine the correlation between the basic lapping conditions and wheel temperature. In work [1] authors developed model to estimate the maximum and average temperature rise of the work surface in lapping. According those models temperature rise depends also on workpiece and plate hardness. Because the second is constant during process, this part of research refer only to the influence of workpieces hardness. They were conducted during lapping the samples made of steel 45. To vary the hardness, samples were divide into three groups each with different Knoop hardness value: 175, 471 and 687. The different hardness values were a result of different heat treatment methods used. Every group after grinding were lapped with the same lapping conditions. In the next step the statistical analysis was conducted. It was verified if the plate temperature is influenced by the workpieces hardness. A hypotheses testing method was use. Results were calculated for temperature rise values measured after 300 minutes of machine working. According to them the influence of workpiece hardness on plate temperature is statistically insignificant.

Abstract: Commonly used as a finishing operation, lapping has been used for achieving ultra-high finishes and close tolerances between mating pieces. Its carried out by applying loose abrasive grains between work and lap surfaces, and causing a relative motion between them resulting in a finish of multi-directional lay. The grains activity (sliding and rolling) in the working gap causes not only the material removal but also the temperature rise of lap plate. This work presents the results of lapping plate temperature rise research. The investigation has been conducted to check the influence of grains size on. It was made during flat lapping with use of ABRALAP 380 lapping machine and infrared camera Thermo Gear G100. The lapping machine executory system consisted of three working conditioning rings. Plate temperature was measured during ceramic (Al2O3) elements lapping. The elements were valve sealing parts. After grinding they were processing with three abrasive grains sizes: F400/17, F800/6.5 and F1200/3. The abrasive mixture was boron carbide powder mixed with kerosene and machine oil with grain concentration 0.25. Other lapping parameters remained constant during process. The wheel speed was 60 rev/min and lapping pressure 0.04 MPa. In the next step the statistical analysis was conducted. It was analysed if the plate temperature is influenced by the grains size. A hypotheses testing method was use. Results were calculated for temperature rise values measured after 300 minutes of machine working. According to them the influence of abrasive grains size on plate temperature rise is statistically insignificant, what is not consisted with the model.

Abstract: By means of finite element method this paper analyzes a new support method used in lapping with solid abrasive and reearches lapping pressure distribution between workpiece machining surface and solid abrasive in lapping process with lapping tool pressed by three support points.From results we can find that by means of the new method the lapping pressure distribution between workpiece machining surface and solid abrasive is improved obviously in lapping process,which is favorable to increase cylindricity of machined hole.Through actual machining process, new method is demonstrated increasing cylindricity accuracy of machined holes of main cylinder significantly.