International Journal of Abrasive Technology (6 papers in press)
Decision Support System for Principal Factors of Grinding Wheel Using Data-Mining Methodology
by Hiroyuki Kodama, Itaru Uotani, Kazuhito Ohashi
Abstract: The recommended grinding conditions are described in five factors (abrasive grain, grain size, grade, structure, and bonding material) of the three main elements (abrasive grain, bonding material, and pore) in the grinding wheel catalog data-set. As systematic arrangement is not made, grinding conditions (cutting speed, table feed, depth of cut) have to be decided on the basis of an experienced engineers information or experience. Moreover, although the setting of the five factors of the three elements of a grinding wheel is important parameter that affects the surface quality and grinding efficiency, it is difficult to determine the optimal combination of workpiece materials and grinding conditions. In this research, a support system for effectively deciding the desired grinding wheel was built by using a decision tree technique, which is one of the data-mining techniques. This system extracts a significant tendency of grinding wheel conditions from catalog data. As a result, a visualization process was proposed in correspondence to the action of the grinding wheel elements and their factors to the material characteristics of the workpiece material. In this report, we produced patterns to support selection of grinding wheels by visualizing the surface grinding wheel selection decision tendency from more amount of data, based on data mixed with JIS standard and maker's catalog data.
Keywords: Data-mining; Decision tree; Grinding wheel; surface grinding.
In-process grinding wheel wear evaluation using digital image processing
by Bahman Azarhoushang, Sebastian Ludwig
Abstract: The microtopography of the grinding tool surface is essential for the result of the grinding process. Micro wear (the flattening of the abrasive grits) and loading (the adhesion of chips between or on the grits), lead to an increase in process forces and temperatures. Subsequently, poor surface qualities, dimensional and profile errors and thermal damage to the workpiece, such as grinding burn, could be induced by the grinding process. Hence, cleaning (dressing) of the grinding wheel is necessary to restore the grinding ability of the tool. Industrial processes usually have short dressing intervals to avoid scrap parts. However, short dressing intervals cause a high loss of the valuable abrasive layer of both grinding and dressing tools. A novel process-oriented measuring method is developed in this study to evaluate quickly and efficiently the surface topography of grinding tools. Images of the tool surface, after being recorded via a camera system, are evaluated by an innovative image processing software for characterizing grit flattening and loading. This article describes the developed technique and the results of the application during grinding processes. The results show a direct proportionality between the output values of the proposed method and the measured grinding forces. Hence, the developed measurement method can be used for the evaluation of the grinding ability and for an assessment of the tool life.
Keywords: grinding; dressing; wheel wear; tool loading; tool life; image processing.
Statistical characteristics and logarithmic EWMA control method of bearing raceways surface roughness by superfinishing
by Shuangjiao Fan, Wangcheng Qiu, Wenxu Chen, Jing Du, Qiang Liu, Guibing Pang
Abstract: The bearing raceway is the main working surface of the bearing and good surface integrity is required. Since superfinishing is an important method for achieving high surface quality, it is usually used as the last processing to play a very essential part in improving the surface integrity of bearing raceway. In this paper, we proposed a superfinishing surface quality control method, by which we could determine whether there were systematic factors that caused surface quality anomalies by measuring and analyzing the roughness data without directly measuring process parameters and environmental indicators. Firstly, we verified through experiment that the surface roughness by superfinishing did not obey the normal distribution but obeyed the logarithmic normal distribution. We interpreted this statistic characteristics by the mechanism of the relationship between roughness and random factors in the superfinishing. Then, according to above findings, and considering the possible trend of surface roughness during continuous processing, we designed a logarithmic Exponentially Weighted Moving Average (EWMA) method to test the surface roughness and judge whether it was under control. Finally, the effectiveness of this surface quality control method in superfinishing was verified by applying it to the actual bearing raceway outer ring machining.
Keywords: Superfinishing; Surface roughness; Lognormal distribution; Quality control; EWMA.
Study on magnetic abrasive finishing combined with electrolytic process
by Xu Sun, Yanhua Zou
Abstract: In order to improve polishing efficiency of magnetic abrasive finishing (MAF) for polishing metal material, we proposed an effective plane magnetic abrasive finishing which combined with electrolytic process. The hardness of workpiece surface can be reduced since passive films generate on the machined surface by electrolytic process. Simultaneously, the generated passive films can be easily removed through the mechanical machining force which generated by friction between magnetic particles and workpiece. Therefore, electrolytic magnetic abrasive finishing (EMAF) can significantly minimize the surface roughness of metal material in a shorter finishing time. EMAF process includes two different finishing steps which are 1st finishing step (EMAF step) and 2nd finishing step (MAF step). The optimal finishing time of two different finishing steps is essential to improve polishing efficiency. In this study, we focused on researching the combinations of EMAF step time and MAF step time for EMAF process. The optimal experimental results of EMAF process showed that the surface roughness Ra can be reduced to less than 30 nm at 4 min first finishing step, the surface roughness Ra can be reduced to 20 nm at 10 min second finishing step. Furthermore, we also analyzed experimental results through observing the change in size of mixed magnetic abrasive after EMAF process experiments.
Keywords: polishing efficiency; magnetic abrasive finishing; electrolytic magnetic abrasive finishing; electrolytic process; passive films.
TheoreticalExperimental Study of Silicon Carbide Grinding
by Mohammed Tharwan
Abstract: The application of hard and brittle materials, commonly exhibited by materials that are produced by burning of minerals at high pressure, has attracted attention with the goal of heightened performance. Traditional grinding generates large cracks and damages surfaces. However, we anticipated that when using a high-precision controlled micro-grinding machine, the improved process of material removal will reduce the surface roughness enhance the surface of brittle materials via increased plastic deformation (ductility). In this experiment, a unique sloped bracket was created to obtain a set of comparison results in one grinding process. Analyses of surface morphology, including scanning electron microscope images of subsurface side cross-sections are shown in this paper. The results show the importance of keeping the depth of cut as small as possible in order to prevent subsurface damage. unique sloped bracket to obtain a set of comparison results in one grinding process. Analyses of surface morphology, includingrnscanning electron microscope images of subsurface side cross-sections are shown in thisrnpaper. The results show the importance of keeping the depth of cut as small as possible inrnorder to prevent subsurface damage.
Keywords: Advanced ceramics; brittle materials; grinding process; grinding force; plastic deformation; fracture damage; SEM; subsurface fracture; critical depth of cut; Silicon carbide and cross-section.
Design and validation of a kinematic numerical dressing model of conventional grinding wheels
by Aitzol Galletebeitia, Jorge Alvarez, Iñigo Pombo, David Barrenetxea, Jose Antonio Sanchez
Abstract: Dressing is one of the most critical parameters that determine the efficiency of subsequent grinding processes. In this study, the analysis and validation of the proposal of a kinematic dressing model for the case of conventional corundum wheels have been done. In this initial analysis, the accuracy of the model will be evaluated by predicting the abrasive surface after the dressing operation for the case of a single point dresser, observing the deviations made between simulations and experimental results. The results obtained show deviations of 19.2%, 7.57% and 19.69% for the roughness parameters root mean square height (Sq), density of peaks (Spd), and reduced peak height (Spk) respectively, which will be indicators of the cutting ability of the grinding wheel and will have influence on the subsequent grinding processes in terms of the surface finish obtained on the finished parts. These results will show the way of future research work, giving useful information for optimizing this numerical model and extending the analysis for different types of dressing tools.
Keywords: dressing, grinding, topography, abrasive surface, grinding wheel.