Resinoid-bonded Wheels Research Articles

High-Efficiency Mirror Grinding of AlN by Ultra-Precision Plane Honing

Plane honing machining of aluminum nitride (AlN) was investigated in this study. AlN has advantageous thermal and dielectric characteristics and is in great demand as a semiconductor mounting board or packaging parts material. However, as AlN is a sintered material, the AlN grains readily detach during machining making it difficult to obtain fine surface roughness at high efficiency. In previous studies, we have developed a new plane honing method that makes it possible to grind hard and brittle materials. In this paper, plane honing experiments of AlN were carried out using a resinoid or vitrified bond wheel. Fine surface roughness could be obtained using the resinoid bond wheel but there was low-machining efficiency due to burying and detachment of abrasives. The vitrified bond wheel, however, enabled high efficiency grinding but resulted in traces of detached AlN grains forming at the machined surface. Highly efficient mirror grinding of AlN could be achieved by using a vitrified bond wheel for semi-finishing and a resinoid bond wheel for finishing.

Improving Process of Surface Roughness with Super-soft Grade Resinoid Bond Wheel (2nd Report)

The surface roughness decreases down to the minimum just after start of plunge grinding with a super-soft grade resinoid bond wheel, of which bonding material is prepared by the interaction of polyvinyl alcohol and thermosetting plastics. In this paper, the grinding method with the resinoid bond wheel is investigated for the finest surface finish of workpiece, based on such minimizing phenomenon of surface roughness. Main conclusions obtained in this paper are as follows : (1) The finest surface finish is obtained by spark-out grinding operation starting just at the moment on which the surface roughness of workpiece decreases down to the minimum. (2) The surface finish by this grinding operation decreases with decreasing the initial surface roughness, but the decrease in surface roughness during the spark-out grinding process increases with increasing initial surface roughness. (3) The repetition of this grinding operation without dressing makes the surface finish smaller than that by a general grinding operation with larger depth of cut before spark-out grinding.

極軟質レジノイド砥石による表面あらさ改善過程の研究（第１報）―研削開始後の表面あらさ最小化現象―

In this paper, an improving process of surface roughness in cylindrical plunge grinding with a super-soft grade resinoid bond wheel, whose bonding material is prepared by the interaction of polyvinyl alcohol and thermosetting plastics, is discussed, analyzing the ground surface profile, the topography of acting wheel surface and so on. Main conclusions obtained in this paper are as follows: (1) Minimizing phenomenon of surface roughness in which surface roughness decreases down to the minimum after start of grinding is remarkably occurred in plunge grinding process with a super-soft grade resinoid bond wheel. And the phenomenon is useful for improving surface roughness by grinding. (2) Decrease of number of simultaneously acting cutting edge by a rapid increase of wheel wear leads to worsen the surface finish just after the point of minimizing surface roughness. (3) The number of simultaneously acting cutting edge is obtained by ground surface profile, topography of acting wheel surface and interference wheel arc length.

移動熱源によるレジノイド砥石のドレッシングに関する研究 （第４報） ＹＡＧレーザの総形ドレッシングへの適用

Form dressing of V-formed resinoid bond wheel by scanning a Q-switched YAG laser beam on the wheel surface is carried out and the form dressing mechanism is experimentally investigated by analyzing initial profile of dressed wheel, variation of wheel tip profile in form grinding process, density and height of cutting edge and so on, comparing with those by a traditional dressing with PVA wheel. Main conclusions obtained in this paper are as follows; (1) Scanning YAG laser beam on V-formed resinoid bond wheel surface results in the better form dressing effect concerning form accuracy or projecting height of cutting edge than a traditional dressing with PVA wheel. (2) Radius of wheel tip decreases with increasing peripheral wheel speed in form dressing because a heat effect on wheel surface by laser beam decreases with an increase of peripheral wheel speed. (3) Laser dressing of V-formed wheel at higher peripheral wheel speed represses a reduction of form accuracy in form grinding process. (4) Radius of dressed wheel tip increases with increasing formed angle and is much affected at larger formed angle by peripheral wheel speed in laser dressing.

PRECISION SURFACE GRINDING CHARACTERISTICS OF CERAMIC MATRIX COMPOSITES AND STRUCTURAL CERAMICS WITH ELECTROLYTIC IN-PROCESS DRESSING

A novel grinding technology that incorporates in-process dressing of metal-bonded superabrasive wheels, known as Electrolytic In-Process Dressing (ELID) has been used for surface grinding of ceramic matrix composites ( CMC) and structural ceramics. The grinding operation was performed with CBN and diamond wheels using various grit sizes and bonds. The ELID grinding was performed with metal-bonded wheels, and the conventional ( non-ELID) grinding was performed with resinoid-bonded wheels. Compared with conventional grinding, ELID grinding with a cast-iron-bonded diamond wheel produced an average peak-to-valley roughness about 100 nm smaller during finish grinding. The scanning electron microscopy ( SEM) also showed improvement of the ground surface with respect to the shape of the grinding marks. ELID grinding showed increased stability in grinding force for high stock removal ( rough grinding) and also produced a significantly lower dulled area at the edge compared with conventional grinding.

移動熱源によるレジノイド砥石のドレッシングに関する研究 (第3報)

The purpose of this study is to establish a new dressing technique of resinoid bond wheel by scanning the point of heat source on wheel surface. Dressing effect with CW YAG laser is testified in previous report. In this paper, Q-switched YAG laser is selected as a dressing tool for making more improvement of dressing effect with YAG laser, and dressing mechanism and grinding characteristics of dressed resinoid bond wheel with Q-switched YAG laser are experimentally discussed by observing the acting wheel surface and analyzing some grinding results with dressed wheel. Furthermore, dressing effect with Q-switched laser is verified by comparing with that with CW laser. Main conclusions obtained in this paper are as follows : (1) Scanning Q-switched YAG laser beam on resinoid bond wheel surface results in better dressing effect than that with CW laser beam. (2) Dressing with Q-switched laser of 2kHz in Q-switch frequency brings out best grinding characteristics of resinoid bond wheel in those of all Q-switch frequency. (3) In lower Q-switch frequency, heat affected structure generated on dressed wheel surface is completely removed as soon as laser beam is irradiated because of radical and frequent variation of heat energy supplied with laser beam.

移動熱源によるレジノイド砥石のドレッシングに関する研究(第2報)

There is a possibility that resinoid bond wheel may thermally be dressed by scanning the heat source on the wheel surface, because bonding material is lower heat resistance than other ones. In this paper, the dressing effect on resinoid bond wheel with YAG laser beam is discussed, observing the acting wheel surface and investigating the grinding characteristics of the wheel dressed by scanning YAG laser beam. Main conclusions obtained in this paper are as follows: (1) Irradiation of YAG laser on resinoid bond wheel surface results in the dressing effect. (2) The effective dressing conditions concerning the peripheral wheel speed and the feed rate of laser beam are determined by the heat energy provided on wheel surface, the transitional characteristic of heating and the width of affected region by scanning of laser beam during one revolution of wheel. (3) Resinoid bonding material become brittle and weak and/or abrasive grains are damaged by irradiation of YAG laser on the wheel surface. (4) Under the same heat energy provided on wheel surface, surface finish increases with a decrease of the peripheral wheel speed in dressing and an increase of the feed rate of laser beam.

移動熱源によるレジノイド砥石のドレッシングに関する研究 (第1報)

移動熱源によるレジノイド砥石のドレッシングに関する研究 (第1報)

硬ぜい材料のシェアモード研削と表面性状

In order to clarify pragmatic aspects of shear-mode grinding, grinding processes and characteristics of ground surfaces were investigated. First, grinding experiments were carried out, using metal bond diamond wheels, resinoid bond diamond wheels and BK7 specimen. Corresponding to the number of infeed, in shear-mode grinding with metal bond wheels, the normal grinding force increases linearly and later reaches a stable state which shows a constant grinding force and no further residual stock removal. But with resinoid bond wheel no stable state can be found. Next, a set of surfaces of BK7 was fabricated by shear-mode grinding, another set by polishing and then the sets were compared. Two techniques were used to evaluate ground glass surfaces : rate of etch and super microindentation. As the results, Etching rate of ground surfaces is “higher” than that of plolished surfaces for the first 0.2 μm. And it is found by super microindentation tests that the ground specimen appears “softer” than the plolished one for the first 0.1 μm.