• Journal of Technologic Dentistry
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• v.33 no.4
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• pp.263-270
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• 2011

Purpose: The grindability of binary Ti-X%Zr(X=10,20,40) alloys in order to develop a Ti alloy with better machinability than unalloyed titanium has been evaluated. Methods: Experimental Ti-Zr alloys were made in an argon-arc melting furnace. Slabs of experimental alloys were ground using a SiC abrasive wheel on an electric handpiece at circumferential speeds(12000,18000,25000 or 30000rpm) by applying a force(200gr). Grinding rate was evaluated by measuring the amount of metal volume removed after grinding for 1 minute and the volume ratio of metal removed compared to the wheel material lost, which was calculated from the diameter loss (grinding ratio). Experimental datas were compared to those for cp Ti(commercially pure titanium) and Ti-6%Al-4%V alloy were used controls. Results: It was observed that the grindability of Ti-Zr alloys increased with an increase in the Zr concentration. More, they are higher than cp Ti, particularly the Ti-20%Zr alloy exhibited the highest grindability at all circumferential speeds. There was significant difference in the grinding rate and grinding ratio between Ti-20%Zr alloy and cp Ti at any speed(p<0.05). Conclusion: By alloying with Zr, the Ti exhibited better grindability at all circumferential speeds. the Ti-20%Zr alloy has a great potential for use as a dental machining alloy.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.11 no.4
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• pp.75-81
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• 2002

In this study, experiments were carried out to investigate the characteristics of grinding and wear process of diamond wheel during grinding ceramic materials. Normal component of grinding resistance was decreasing while increase of spindle speed. The resistance of vitrified bond wheel was less then that of resinoid bond wheel because of imbedded large holes on the surface of cutting edge. Surface roughness was decreasing while increase of spindle speed. The surface roughness using vitrified bond wheel was less than that of resinoid bond wheel because of small elastic deformation. After continuous finding of ceramics, cutting edge ratio of resinoid bond wheel decreased. For the case of vitrified bond wheel, cutting edge ratio did not change.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2001.10a
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• pp.344-348
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• 2001

In this study, experiments were carried out to investigate the characteristics of grinding and wear process of diamond wheel grinding ceramic materials. Normal component of grinding resistance was decreasing while increase of spindle speed. The resistance of vitrified bond wheel was less then that of resinoid bond wheel because of imbedded large holes on the surface of cutting edge. Surface roughness was decreasing while increase of spindle speed. The surface roughness after using vitrified bond wheel was less than that of resinoid bond wheel because of small elastic deformation. After continuous grinding of ceramics, cutting edge ratio of resinoid bond wheel decreases. For the case of vitrified bond wheel, cutting edge ratio does not change.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.05a
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• pp.952-955
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• 2002

$WC-3%(Cr_3C_2)-2%(Mo_2C)-12%Ni$ carbides were ground with three different types of electroplated diamond wheels with respect to grain friability. The grinding ratio in the case of the highest toughness grains, A becomes the highest at the workpiece speeds of 40 and 70mm/min exhibiting larger effect with smaller workpiece speed. The grinding ratio with the medium toughness grain is higher than that of grain A at higher workpiece speeds than 100mm/min. The surface roughness becomes smaller with increasing the grain friability The increasing rate on surface roughness with the increase of workpiece speed becomes higher with using the grain of lower friability.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.04b
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• pp.118-123
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• 1995

A new grindignwheel was developed for the high performance gfinding of difficult-to-grind materials. Te grinding performance (such as grinding forces, grinding ratio, and surface roughness of ground surface) of the newly developed wheel was evaluated through experiments. Experimental results show that the performance of the newly developed wheel is superior to conventional alumina wheel and comparable to the S-G wheel.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.7
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• pp.106-111
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• 2001

This study reports the grinding characteristics of quartz. Grinding experiments were performed at various grinding conditions including wheel mesh, table speed and depth of cut. The grinding forces and specific grinding energies were measured. Surface roughness was also measured with tracer and the ground surfaces were observed with SEM. A new parameter SDR(Surface roughness Direction Ratio) is proposed to characterize the grinding mechanisms of quartz. A set of experiments was performed to verify the effectiveness of the suggested parameter. The experimental results indicate that the ductile mode is the dominant material removal mode at the grinding conditions which show the higher value of SDR whereas the material is removed by brittle fracture in a lower value of SDR value increases with wheel mesh size.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.12 no.5
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• pp.36-41
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• 2013

One of the problems in grinding process using a machining center(MC) with a small diametric wheels is machining error due to decrease of the quill diameter. In this study, side-cut grinding is performed with a vitrified bonded CBN wheel on the machining center. Grinding experiments are performed at various grinding conditions including quill length, quill diameter and depth of cut. The effect on the grinding force, machining error and surface roughness due to the change of the quill rigidity are investigated experimentally. The slenderness ratio of the quill is significant factor to analyse the change of the grinding force and machining error.

• Journal of the Korean Society for Precision Engineering
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• v.10 no.2
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• pp.190-196
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• 1993

Internal high speed grinding under several high grinding wheel speed condition has been performed in this study for the effects have analyzed and compared with the grinding power, grinding tangential force and accuracy of surface with the carbon tool steel(SK3). The following results have been obtained: (1) Under the workpiece speed constant condition, increasing the grinding speed, the tangential force is decreased, and on the contrary, accuracy of surface is improved. (2) Under the speed ratio (V$_{w}$/V$_{s}$) contant condition it is possible to increase the high machining efficiency constraint to tangential grinding force constant.ant.

• Journal of Technologic Dentistry
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• v.35 no.4
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• pp.295-302
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• 2013

Purpose: The grindability of Ti-10%Zr-X%Cr(X=0,1,3) alloys in order to develop Ti alloys for dental applications with better machinability than unalloyed titanium has been evaluated. Methods: Experimental Ti-10%Zr-X%Cr(X=0,1,3) alloys were made in an argon-arc melting furnace. Slabs of experimental alloys were ground using a SiC abrasive wheel on an electric handpiece at one of the four rotational speeds of the wheel (12000, 18000, 25000 or 30000rpm) by applying a force(100gf). Grindability was evaluated by measuring the amount of metal volume removed per minute(grinding rate) and the volume ratio of metal removed compared to the wheel material lost, which was calculated from the diameter loss (grinding ratio). Experimental datas were compared the results with those of cp-Ti(commercially pure titanium) Results: It was observed that the grindability of Ti-10%Zr-X%Cr(X=0,1,3) alloys increased with an increase in the Cr concentration. More, they are higher than cp-Ti, particularly the Ti-10%Zr-3%Cr alloy exhibited the highest grindability at all rotational speeds except 12000rpm. There was significant difference in the grinding rate and grinding ratio between Ti-10%Zr-3%Cr alloy and cp-Ti at all rotational speeds(p<0.05). Conclusion: The Ti-10%Zr-3%Cr alloy exhibited better grindability at high rotational speeds, great potential for use as a dental machining alloy.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.1 s.94
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• pp.167-173
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• 1999

This paper presents results of monitoring grinding processes with on-the-machine measurement of surface roughness by using nux ratios of scattered lights. A compact, on-the-machine surface roughness sensor. which consists of a diodelaser and several optic units. is developed. The control unit is also developed. The developed sensor together with the controller is applied for monitoring grinding processes of two different grinding machines. Experimental results show that the nux ratios and their standard deviations measured by the developed sensor over the entire ground surface are useful for monitoring grinding conditions. In particular, the sensor and the control unit are proved to be useful for monitoring grinding processes in order to detect abnormal grinding conditions and dressing time.