Abstract: A process for grinding deep profiled slots in a nickel-based alloy with electroplated cubic boron nitride (CBN) wheels and straight oil is presented. These slots were prepared by this process for further grinding with electroplated CBN quills to generate the final fir-tree slots in gas turbine disks. Fir-tree slots are usually machined using broaching. The application of broaching, however, is limited in the case of nickel-based powder metal alloys due to short life of broaching tools and the effect on machined surface integrity. Grinding tests were first conducted on rectangular blocks to grind slots without inclinations at a fixed wheel speed vs = 60 m/s to identify the combinations of depths of cut, workspeed, and up/down grinding satisfying the requirements of ground surface quality and material removal rate. Inclined slots were then ground with the identified condition on a block representing a segment of an actual turbine disk to validate the condition. The wheel life was finally tested by grinding all the slots on the actual disk. Grinding power was measured, and the ground surfaces were inspected for any sign of burning. Preset target material removal rate and wheel life were obtained. It was found that electroplated CBN wheels are capable of grinding deep profiled slots on the difficult-to-cut nickel-based alloy.
Abstract: This paper uses micro-grinding tool with 500# grains and 0.9 mm diameter to grind nickel-based superalloy Inconel600 through three factors(grinding depth, feed rate, spindle speed ) at three levels orthogonal grinding experiment in mesoscopic scale. Then according to the range analysis of surface roughness, the primary and secondary influencial factors are found; the micro grinding parameters are optimized ,the results show: the influence of the feed rate(vf)is the biggest, followed by the spindle speed(n), the grinding depth(ap) is minimal, when n=50kr/min, vf=100μm/s, ap=6μm, the grinding surface roughness is minimum: Ra=579nm; finally , the regression mathematical model of micro grinding surface roughness is established, the relative error of the calculated value and experimental measurements is low, showing that this regression mathematical model is accurate and effective. This study provides a theoretical basis for the micro grinding parameters and surface quality control of nickel-based superally.
Abstract: In recent development of dental restoration, zirconia has been used as a prosthetic material due to their enhanced properties of fracture strength and toughness compared to other ceramic materials. Zirconia based ceramic materials are used in structural application in engineering, such as in the manufacture of cutting tools, gas sensors, refractories. Grinding was used as the efficient technique to finish ceramic materials. Due to the hard and brittle nature of a ceramic material, the grounded components were left with surface and subsurface damages. In this paper, the influence of the grinding parameters on the grindability of yttrium partially stabilized zirconia was carried out using a diamond grinding wheel. The resin bonded grinding wheel was used to analyze the grinding behavior of the material. The grinding force and surface roughness were measured during the grinding process and the experiments were conducted under conventional flooded conditions. The relationship between the surface finish and grinding parameters such as depth of cut, wheel speed were analyzed.
Abstract: Micro-grinding is an important processing method in micro-manufacturing field. The influence factors of surface quality in micro-grinding are discussed in the article. The models of finite element analysis (FEA) in micro-grinding H62 with electroplated CBN micro-grinding tool were established. The influence of different grinding factors on the surface quality of the work-piece was discussed by FEA. Different grains sizes were considered to reveal the influence rules on surface roughness in grinding experiments. The results show that the surface roughness decreases with the decreasing of the feed speed and the increasing of the grinding speed. A better surface quality can be achieved with smaller grains sizes. The minimum surface roughness can reach 481nm in side grinding H62.
Abstract: The zirconia parts are limited by machined surface quality. The grinding force is one of the most important parameters of grinding and has effects on surface quality. The MK2710 grinder and resin bond diamond wheels were used in zirconia grinding. The grinding force was obtained by Kistler dynamometer. The paper focused on wheel speed and grain size on grinding force, and examined the surface by SEM. The research results indicated that decreasing the grain size, the grinding force increased and the surface quality improved, and increasing wheel speed could decrease grinding force to improve grinding surface quality. The results can improve zirconia ceramic parts surface quality and promote application.
Abstract: Oral adjusting of ceramic prostheses involving abrasive machining using dental high-speed rotary cutting instruments is a central process in restorative dentistry, because this process affects not only restorative quality but also patients’ comfort. However, the dental grinding process, especially dental grinding of high-strength ceramic prostheses, is less understood in clinical dentistry. This paper presents dental grinding of an innovative high-strength lithium disilicate ceramic in in vitro oral adjusting regime using a dental high-speed electric handpiece and diamond burs. The dental abrasive machining characteristics were quantitatively evaluated in terms of normal and tangential forces, force ratio, and specific grinding energy as functions of clinically relevant dental grinding variables including depth of cut and feed rate and feed direction of burs. The results showed that the dental tangential and normal forces and specific grinding energy exhibited significant dependences on depth of cut, feed rate and direction of burs, but revealed significantly small scales compared to engineering machining regime. Clinical implication was given that down grinding undoubtedly reduced the abrasive adjusting forces to relieve patients’ discomfort in oral regime. Moreover, dentists must be cautious in dental abrasive adjusting of the lithium disilicate ceramic prostheses at or beyond the specific material removal rate of 2.4 mm3/min due to significantly large forces and vibrations.
Abstract: In abrasive belt grinding, abrasive belt granularity, abrasive belt speed,feeding speed and grinding force have a great influence on the surface roughness. In order to predicate the surface roughness of Ti-6Al-4V,a response surface methodology are used to build the model to predict surface roughness,and the influence of various parameters on surface roughness was analysed. The research shows that with the abrasive belt granularity and abrasive belt speed increasing,the work piece surface roughness decreases;with the grinding force and feeding speed increasing,the work piece surface roughness increases. Through the test,the response surface methodology with high prediction accuracy,provides a theoretical basis for the reasonable selection of abrasive belt grinding parameters.
Abstract: Structural textural surfaces are those surfaces that have designed feature intended to give specific functional performance. In the last few decades, the understanding of structured surface texture, particularly at a micro and nanometre scale, has played a fundamental role in the development of many advanced applications. After a brief review of current manufacturing methods for textural surface, this paper examines the surface creation during grinding by analysing the kinematics of grinding and associated wheel dressing processes. It has been demonstrated that the features of structural surface can be determined by carefully selected dressing and grinding conditions. The grinding speed ratio between workpiece and wheel is an important factor in determine the layout of the structural pattern generated on the workpiece. The grinding depth not only affects the structural feature depth but also the length and width of the surface structure. The uniformity and repeatability of actual ground feature shape is influenced by the arbitrary nature of distribution of grinding abrasives.
Abstract: Cylindrical parts with a protrusion are expected to be used in the components of consumer electronics and automotive products. The machining efficiency of these parts is very low, making them difficult to be mass-produced. The aim of our present work is to develop a highly accurate and highly efficient grinding process for a cylindrical surface with a protrusion. This paper describes the results of experiments using a straight cup-shaped grinding wheel. The following conclusions can be drawn. (1) To prevent uneven wear of the grinding wheel, an oscillation operation is necessary during the grinding process. (2) By employing the straight cup-shaped grinding wheel, the grinding process is realized with the aim of achieving the following: high machining accuracy, roundness below 3 μm, straightness below 2 μm, and surface roughness below 2 μmRzjis.