Masakazu Miyashita

Observation and analysis of grinding scratch generation around the central part of a component

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.

Positioning of a 200 kg carriage on plain bearing guideways to nanometer accuracy with a force-operated linear actuator

The design specifications for ultraprecision grinding machines require the realization of high resolution, of nanometer order, and high stiffness, of more than 10 N nm-1. A new hydraulic actuator, a force-operated hydraulic actuator, and a composite bearing guideway, which defines the bearing pressure distribution, are proposed to meet these requirements. By application of these proposals to the feed mechanism of a carriage on plain bearing guideways, the authors have tried to achieve simultaneously a high damping effect on bearing friction and also a high feed resolution for ultraprecision turning machines in spite of bearing friction. The test rig of the positioning servo control system of the force-operated actuator could respond up to 0.05 nm/step and achieved a high stiffness of up to 66 N nm-1 and frequency range of 500 rad s-1. The test rig of the positioning servo control of a 200 kg carriage on plain bearing guideways with the force-operated hydraulic actuator achieved a feed resolution of 1 nm/step.

Ductile mode grinding of brittle materials with newly designed centerless grinding machine

other for coarse abrasive grinding wheels with coarsen grains in size of more than the dc value. Thegrinding criterion for the former case is Type 1 and for the latter is Type 2 of ductile mode criterion.Here, Type 1 is separat1 into Type 1A for the principle of motion copying and Type lB for pressure

Review of carriage feed mechanism with nanometer resolution

A carriage feed is a mechanism composed of a guide and a feed. The four parameters of carriage feed accuracy are: feed reference accuracy, feed resolution, guide reference accuracy and guide component constraint accuracy. Each parameter can be improved through the use of servo techniques. This paper discusses, on the basis of kinematic principles, a carriage feed mechanism with no lost motion and a fine feed resolution with high reliability and accuracy in the nanometer range. For nanometer positioning of carriage feed mechanisms, both ball and roller bearing and hydrostatic support mechanisms controlled by force-operated position control can be used. Capacitive transducers and feedback sensors of optical linear scale are also applicable in consideration of S/N ratio.

Strategies for truing/dressing technique and precision grinding performance of superabrasive wheel for brittle-material components

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.

Proposal of a new mode of NC command for implementation of profile accuracy and productivity in grinding

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.

Development of an Ultraprecision Grinding Equipment for Ductile Node Surface Finishing of Brittle Materials

Ductile mode ultraprecision grinding technology Is highly expected as a next-stage machining process of semiconductor materials. For industrially realizing this technology, We have developed an ultraprecision surface grinding equipment. This equipment is composed of ultraprecision systems such as force-operated linear actuator, composite bearing guideway mechanism, load compensation unit, spindle fixed wheel driving unit and so on. By these systems, inching resolusion of the grinding wheel head reached lOnm, and the loop stiffness between the grinding wheel and the working table was 150 N/μm. SAM observations revealed that no cracks were remaining under ground surface. The thickness of dislocation layer remained on the ground silicon wafers is not more than 0.5/μm. The flatness TTV of 6″ silicon plate ground by this equipment was under 0.6μm.

Way to nanogrinding technology

Precision finishing process of hard and brittle material components such as single crystal silicon wafer and magnetic head consists of lapping and polishing which depend too much on skilled labor. This process is based on the traditional optical production technology and entirely different from the automated mass production technique in automobile production. Instead of traditional lapping and polishing, the nanogrinding is proposed as a new stock removal machining to generate optical surface on brittle materials. By this new technology, the damage free surface which is the same one produced by lapping and polishing can be obtained on brittle materials, and the free carvature can also be generated on brittle materials. This technology is based on the motion copying principle which is the same as in case of metal parts machining. The new nanogrinding technology is anticipated to be adapted as the machining technique suitable for automated mass production, because the stable machining on the level of optical production technique is expected to be obtained by the traditional lapping and polishing.

Vibration Control For Ultraprecision Motion Machineries

Development of ultraprecision machines requires motion mechanisms with dynamic characteristics being sufficiently resistive to environmental disturbances as well as vibration control devices isolating from them. In the paper active application of frictional forces to the machines are proposed in viewpoint of this point. Further, new strategies for various problems resulting from application of frictional forces are also proposed for linear feed mechanism and the test results are shown. They are load compensation unit, composite bearing guideway and force operation feed mechanism.