Papers by Keyword: Micro Grinding

Abstract: The miniaturization of components and the functionalization via micro structures demands for flexible and economic manufacturing processes. Micro machining, i.e. micro milling and micro grinding can meet these requirements. In this paper, desktop-sized machine tools and their components that were developed at our institute are presented. With those machine tools, micro tools can be machined and used in one clamping, allowing for increased machining quality. Grooves milled with such machine tools achieve a bottom surface roughness below 10 nanometer.

Abstract: This paper presents a micro-grinding experiment on soda-lime glass to study the surface quality effective factors during micro grinding on hard brittle materials. The process of micro-grinding on soda-lime glass is showed in this paper and micro-grinding equipments are designed, fz(feed rate), ap (grinding depth), vg(Grinding speed) in micro-grinding brittle materials and their effects to surface quality have been discussed by experiments which were carried out on a desktop micro machine developed by NEU. Results proved that fz is the most important factor to the surface quality, and low surface roughness could be achieved by high vg and low fz in micro-grinding soda-lime glass.

Abstract: The process of micro-grinding on hard brittle glass is shown in this paper, micro-grinding equipments are designed by tools of electroplated diamond, fz(feed rate), ap (grinding depth), vg(Grinding speed) in micro-grinding brittle materials and their effects to surface quality have been discussed. It has been demonstrated that low surface roughness could be achieved by high vg and low fz. The roughness of Soda-lime glass accomplished by fz:100μm/s, ap:30μm, vg:120000rpm in the experiment is about 78nm.

Abstract: This paper aims to develop a laser assisted grinding process capable of manufacturing micro features in high strength materials. A diode laser with wavelength 808 nm was set on a precision grinding machine. Micro grooves were fabricated on high strength materials including silicon nitride and aluminium oxide by using the laser assisted grinding process, i.e. laser pre-heat workpiece flowed by micro grinding. The experimental results showed that the laser assisted grinding process resulted in deeper grooves due to thermal expansion of workpiece materials caused by laser heating. However, the machined surface roughness was more consistently better than that obtained using solo grinding process and applying coolant. No subsurface damage was observed in the SEM images of cross sections of the machined workpieces when laser assisted grinding process was used.

Abstract: This paper presents a novel micro shaft grinding tool is fabricated by cold sprayed with CBN grains, and a micro-grinding experiment is carried out to study micro grinding principle of the fabricated tools. The manufacturing is carried out on a desktop micro machine developed by NEU. Influences caused by particle size on surface quality has been discussed, it has been tested that low surface roughness could be achieved on 3000 particle size of micro shaft grinding tool, the roughness accomplished in the experiment is about 0.086μm.

Abstract: This paper presents a micro-grinding experiment on AISI 1020 steel to study micro grinding principle. A novel micro shaft grinding tool is fabricated by cold sprayed with CBN grains, the manufacturing is carried out on a desktop micro machine developed by NEU. Influences caused by particle size on surface quality has been discussed, it has been tested that low surface roughness could be achieved on 3000 particle size of micro shaft grinding tool, the roughness of AISI 1020 steel accomplished in the experiment is about 0.086 μm.

Abstract: Brittle and hard materials are problematic to mechanically micro machine due to damage resulting from material removal by brittle fracture, cutting force-induced tool deflection or breakage and tool wear. As a result, the forces arising from the cutting process are important parameter for material removal. This study was undertaken to investigate the effect of cutting conditions on cutting forces and the machined surface during the glass micro grinding using on-machine fabricated (Poly Crystalline Diamond) PCD tool. Experimental results showed that an increase in depth of cut and feed rate can result in increase of cutting forces and surface roughness as well. Among the forces in 3 axes, force along feed direction is found to be larger, which played a major role in material removal. Finally, it is observed that PCD tool exhibits promising behaviour to machine brittle material like BK-7 glass for producing micro molds and micro fluidic devices, since it has better wear resistance, experiences less cutting forces and generates smooth surfaces with Ra value of as low as 12.79 nm.

Abstract: CVD-diamond microgrinding wheels can be used in the microsystems technology, e.g. to produce microarrays consisting of glass. These novel tools have the same advantages as CVD-diamond microgrinding pins, but they can even be used with higher cutting velocities and higher material removal rates. Furthermore, micro cracks and chipping could be minimized and better surface qualities could be achieved. The tool body consists of cemented carbide. After designing a suitable geometry for these novel micro grinding tools, they had to be produced with cup wheels. The design, which has already been tested, is a grinding wheel of the type “1A1”. The CVD-diamond microgrinding wheels were analyzed with a scanning electron microscope (SEM) due to their topography and crystallite size. The microgrinding wheels were tested with regard to their grinding behavior. During the investigations, cutting forces were measured and afterwards analyzed. In addition, surface roughnesses were measured, so that the materials could be compared with regard to their grindability. The tool wear was evaluated by means of SEM-pictures. They showed the wear resisting behavior of the CVD-diamond microgrinding wheels. Even after grinding a high material removal rate in the hard ceramic aluminum nitride, only a small clogging of the microgrinding wheel was monitored. The slight increase of the cutting force is another indicator for the clogging. It can be summarized that novel grinding tools could be successfully developed and tested with hard and brittle materials. During these tests, the cutting forces and surface roughnesses as well as wear behavior and end of tool life were determined and will be shown in this publication.

Abstract: A novel grinding approach of micro pyramid-structured surface is proposed by using a 60º V-tip of #600 diamond grinding wheel in CNC system. The research objective is to understand the micro grindability of various hard and brittle materials including quartz glass, silicon, SiC ceramics and WC alloy. First, a CNC mutual-wear truing approach was developed to sharpen the wheel V-tip; then, the wheel V-tip was employed to pattern the micro pyramidal array on workpiece surface along CNC tool paths; finally, the machined micro-structured surface and its form accuracy and aspect ratio were investigated. It is shown that this CNC mutual-wear truing approach can not only produce a V-shaped diamond grinding wheel, but also sharpen the diamond grain edges on the wheel V-tip. This wheel V-tip may be used to machine the micron-scale pyramid arrays on silicon, SiC ceramics and WC alloy surfaces with CNC level reticulated cross tool paths, the depth of cut of 1 m and on-machine V-tip form-truing process. Although the average form error of machined micro-structured surface is very small, its pyramidal tops and groove bottoms appear very large form errors, which are dominated by the wheel V-tip sharpness and the grinding conditions, respectively. This leads to a decrease in the aspect ratio by about 38%, 30% and 14% in contrast to the ideal one of 0.87 for silicon, SiC ceramics and WC alloy, respectively.

Abstract: A truing technique that can be used to shape the tip of an electroformed diamond tool into a hemisphere and flatten diamond grains on the tool working surface at the same level as the bond face was developed. A polycrystalline diamond disk whose top surface roughened by electrical discharge machining was partially flattened by grinding was used as a truer. Diamond grains on the tool working surface were successfully flattened along the hemispherical tool profile when the grains mesh size of #1000 was employed. In addition, a grinding test using glasslike carbon as a work material revealed that a surface roughness of less than 50 nm Rz could be obtained in both cases when moving the tool on contour and scanning paths.