A grinding wheel with fine abrasives is conventionally applied for precision grinding. In particular the precision grinding of brittle materials in the region of ductile mode chip removal is based on the fine abrasive with grain size of a few micron to sub-micron. This paper shows possibility of ultraprecision grinding with coarse abrasive wheel of grain size of over ten microns and also the precision grinding technology with coarse abrasive wheel can realize high productivity in precision riding of brittle materials. The key of the technology is dressing/truing of superabrasive wheel or control of height distribution of grain tops. The strategies on truing/dressing technique of superabrasive wheel is proposed and a example to be applied to technique is shown. The surface finish of 0.9 nm Ra is achieved for borosilicate glass ground with the metal bonded diamond wheel with number 800.
A profile grinding equipped with a new mode of NC command is characteristic of being provided with a feedback sensor for detecting a displacement of table to control plunge feed and a sensor for detecting grinding load to decide selectively a sparkout time or a traverse feed rate. The new model gives a plunge feed command for motion copying and also a selective size reduction or sparkout time command similar to pressure copying. As a result, profile area with large error can be fast removed under high grinding load and for the other area, profile feed rate can be increased by shortening sparkout time selectively. Applying the new mode NC command, a high profile accuracy and also high productivity in grinding can be expected.
Ductile mode grinding (DMG) process, which can provide geometric accuracy of 0. 1 tm without cracks on the surface, is highly expected as a next stage machining process of brittle materials. DMG can be achieved when grain depth of cut in uncut chipthickness is controlled to under the ductile-brittle transition value, dc, dc 0. 1 pm for Si wafer'. It is required to develop both ultraprecision grinding machine (2) and truing technology of diamond wheels. In particular ,for realizing ductile mode grinding of brittle materials, the absolute requirement is that the grain depth of cut dg of all active cutting edges has to be smaller than the ductile-brittle transition value, do.. An extruded cutting edge (ECE) from the envelope of adjacent cutting edges causes a serious problem of scratch generation. The present paper deals with observation and analysis of grinding scratch generation around central part of 5, wafers ground with diamond wheels on rotary work-spindle machines.
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