Stock Removal Rate Research Articles

A lapping and polishing process to achieve high quality alumina surfaces for applications in device fabrication

A lapping process for achieving high quality alumina (Al 2O 3) surfaces was investigated. Alumina films were sputter deposited on thick TiCAl 2O 3 ceramic wafers. Polishing of these films was carried out on pitch plates (organic resin melted and set on the circular disk of a lapping machine). Abrasives with different grit sizes, 0.05–1.0 μm, were tried together with different lapping process parameters. Qualitu of the lapped surface was studied in terms of roughness and flatness. Stock removal rates were also measured. Correlation of surface quality with lapping parameters was established to achieve process optimization. Scratch-free polished alumina surfaces were obtained by using this technique. Specific applications of the process in the fabrication of magnetic recording devices are indicated.

Improvement of EDM Efficiency by Supplying Oxygen Gas into Gap

This paper describes a new method of EDM which is supplied with oxygen gas into the discharge gap, when a water based dielectric is used. It is found that the stock removal rate is increased due to the enlarged volume of discharged crater and more frequent occurence of discharge. During the analysis and discussions, attentions are paid on the heat and force caused by the activated chemical reactions of oxygen.

金型磨き作業の知識獲得と自動化に関する研究 （第１報） 金型熟練工の手磨き特性

The purpose of this paper is to acquire the knowledge of a skilled machinist in respect to polishing operations of injection mold cavities, in order to develop a high performance polishing machine. Polishing experiments with different kinds of polishing tools are carried out not only by a skilled machinist's handwork, but also by mechanical method. The polishing properties of a skilled machinist in respect to surface roughness, stock removal and scratch are obtained and analyzed quantitatively. The surface roughness decreases exponentially with the increase of polishing times. The surface roughness (Ra) depends on the following threeactors : roughness before polishing (Ro), final surface roughness (Re) and exponential coefficient (a). The stock removal curve can be represented approximately by two lines and the polishing times corresponding to the intersection of the two lines coincide with the critical polishing times in which the surface becomes better by a degree of 90%. Differences of surface roughnesses between hand polishing and mechanical polishing are small being only 10%. However, the rate of stock removal to polishing times in hand polishing is large being about twice that in mechanical polishing, and the rate of scratch to roughness in hand polishing is kept constant with 4 for different kinds of tools and smaller than that in mechanical polishing.

エマルション型研削油剤での添加剤が研削性能に及ぼす影響

We study here the effects on grinding ratio, tangential grinding force and surface roughness of emulsion grinding fluid supplied by a MAKITSUKE NOZZLE. As the distribution of the size of oil particles grows, the grinding ability increases. Effects of chlorinated or sulfurized additives are examined. An emulsion grinding fluid containing effective chlorinated and sulfurized additives (MGF-3) is developed. It is clarified that MGF-3 has a high grinding ability and high stock removal rates.

シリコンウエハの鏡面仕上 (第2報)

This paper explains how the temperature of Si wafers during polishing affects their flatness after polishing. During the polishing operation, the temperature distribution of the wafer was measured using thermistor sensors (0.1 K accuracy) attached to the wafer opposite the surface being polished. It is made clear that this distribution is affected by the pouring method and temperature of the polishing reagent. The temperature near the center of the Si wafer during polishing is about 1.0 K higher than that of the surrounding area. As a result, chemical action is activated, increasing the stock removal rate at the center, and the polishing wafer is out of flat by 0.6-1.2μm in a concave direction.

Improvement of Straightness in Precision Cut-Off Grinding Using Thin Diamond Wheels

Summary This paper deals with straightness in precision cut—off grinding of alumina ceramics with such thin diamond wheels as 0.25mm. It was made clear that the straightness of the sliced surface strongly correlates with the axial deflection of a thin grinding wheel, which is caused by the side forces acting on the side surfaces of the grinding wheel. As a result, the straightness can be improved remarkably according to decreasing the side force both by decreasing the depth of cut with retaining a stock removal rate, and by improving the flatness on the side surfaces of the grinding wheel.

プランジ研削の最適化に関する研究

In this paper, a new method is proposed to minimize the grinding cycle time of cylindrical plunge grinding operations. The proposed method is based on the changing of the velocity ratio (the peripheral speed of workpiece/the peripheral speed of grinding wheel) in a grinding cycle although the conventional plunge grinding has been done with a constant velocity ratio in one cycle. The proposed plunge grinding cycle consists of three stages ; that is, (1) the rough grinding with high velocity ratio, (2) the fine grinding with low velocity ratio and (3) the spark-out grinding with low velocity ratio. At the first stage (the rough grinding), the reduction in grinding time is planed by high stock removal rate based on high velocity ratio. On the other hand, the main role at the second stage (the fine grinding) and the third stage (the spark-out grinding) is improving the surface quality of the workpiece, especially the decrease of the surface roughness and the damaged surface layer by relatively low velocity ratio. The validity of this method has been examined by computer simulations and some experiments. As a result of this, it has been cleared that the cylindrical plunge grinding with a high efficiency can be realized without the deterioration of the workpiece surface quality by using the proposed grinding method.

Superpolishing sapphire: A method to produce atomically flat and damage free surfaces

Superpolishing of sapphire is done in direct contact to a rotating tin lap using silica aquasol as a polishing liquid. The roughness is studied with a Talystep profiler, and the crystallinity of the upper atomic layers is investigated by RHEED technique. The extremely small stock-removal rates are determined as a function of each important working parameter with all other parameters unchanged. These results are discussed in terms of the hydrothermal wear model.

シリコンウエハの鏡面仕上 Ｉ ポリシャ表面温度の変化過程について

This paper deals with the effect of the factors governing polisher surface temperature, which is strongly correlated with stock removal rate, on the mirror polishing of Si wafers. The factors investigated here are the coefficient of friction between the polisher and the Si wafer, the temperature of the polishing reagent, and the polishing area ratio, which is defined as the ratio of the total wafer polishing area on a polisher relative to the effective area of the polisher. The increase of these parameters promotes the chemical reaction between the Si wafers and either the polishing reagent or the polisher, and results in improving the stock removal rate. The polisher surface temperature, indicative of the chemical activity, can be easily controlled by the temperature of the polishing reagent, and as a result a stock removal rate more than 4 times higher can be achieved without deterioration in quality of Si wafers.

有気孔メタルボンドダイヤモンドホイールの開発とその研削特性

This paper describes the results of developmental research on the new porous diamond wheels based on the aluminium alloys. Structual features of the new wheel include various aluminide compounds (Ti/Al or Fe/Al phase) as a part of bond matrix and soluble-type compounds (Na2SO4, MgSO4) as a pore formative substance. The results obtained are as follows : (1) The porous aluminium wheel containing a Ti/Al phase and Na2SO4-compound showed the intermediate performance between the usual metal bonded wheel and resin bonded wheel. (2) In comparison with the consumed power or the tangential grinding force, the porous wheel showed superior performance compared with the poreless diamond wheel. (3) Wear loss of the porous Ti/Al-wheel with MgSO4 compound is smaller than the Na2SO4-wheel, but it has no recognizable effect in the Fe/Al-wheel. (4) Wear loss of the Ti/Al-wheel containing the tough-particles belongs to the G 5-group is very smaller, and the stock removal rate is doubled comparing with the G 2-wheel.

フェライト材のメカノケミカルポリシング ＩＩ 加工能率，加工変質層に及ぼす加工条件の影響

The purpose of this paper is to discuss the method for improving the stock removal rate without growing the damaged layer in the mechano-chemical polishing. Polishing plates made of either tin or lead are used with a polishing fluid chemically active to ferrite such as hydrochloric acid. The stock removal rate can be increased by more than two times and the damaged layer of the ferrite can be reduced to less than one fourth as compared with those in the mechanical polishing process, when a tin plate and crystalline alumina mixed with 5% hydrochloric acid are used in the new polishing process. It is comprehensible that these good effects are obtained by electro-chemical action which is added to the mechanical polishing for the cause of composing the local cell between a polishing plate and a ferrite.

フラクチャマシニングによるセラミックスの高能率研削に関する研究

The grinding of ceramics with diamond wheels has disadvantages such as low stock removal rates or reduction of the strength of workpieces. This paper describes scratch tests with single point diamond tools and grinding experiments with diamond wheels in order to analyze the grinding mechanism of ceramics and overcome these disadvantages. The following results were obtained. (1) Specific grinding energy of ceramics is strongly correlated with fracture toughness and hardness. (2) Chips are removed as a result of the generation and growth of cracks, so called “fracture machining”. (3) Fracture machining is achieved at a high depth of cut, and improves both the stock removal rate and the grinding ratio. (4) The crack layer induced by fracture machining at a 40 μm depth of cut and 20m/min table speed can be removed by the finished grinding using a # 800 diamond wheel and the bending strength of SiC results in recovering up to that of the base material.

ＣＢＮ砥石によるクリープフィード研削に関する研究 砥石摩耗特性

This paper presents the experimental investigation on the wear characteristics of CBN wheels in creep feed grinding. The obtained results are as follows : (1) As the wheel depth of cut decreases at a constant stock removal rate, the grinding force per a grain cutting edge fts increases almost power functionally and the mechanism of wheel wear changes rapidly from the attrition type to the micro-fracture type when the fts value exceeds a critical value fts (c). (2) The volumetric wheel wear rate takes a minimum value at the critical condition.

Effects of static stiffness of surface grinding machine and grinding conditions upon the surface characteristics of advanced ceramic

Effects of the grinding conditions and the static stiffness of surface grinding machine on surface characteristics of an advanced ceramic are described. There exists a critical point on the relations between table feed rate and grinding force under the conditions of constant stock removal rate. Surface characteristics of ceramics ground in higher table feed rate differ from that of lower table feed rate. And the grinding force obtained was smaller by using surface grinding machine with lower static stiffness.

磁性流体利用の作用砥粒数制御研磨

Need for the controllable finishing of materials such as semiconductors and ceramics, has remarkably increased in the fields of electronics and precision machinary. A new lapping method has been developed by utilizing functional magnetic fluid which has the ability to move in the magnetic field. The magnetic fluid is a suspension of fine magnetite Fe3O4(smaller than 150A) in liquid. This lapping method is based on the floatation of nonmagnetic grains suspended into the magnetic fluid in the magnetic field. Lapping experiments were conducted on soda lime glass. It was found from the experiments that the new lapping method is able to control the stock removal rate through varying the current to the electromagnet. The present method may be usefully employed in finishing such parts as aspherical lenses.

フェライト材のメカノケミカルポリシング Ｉ 加工液，定盤材質及び加工機構について

This paper presents some experimental results on mechano-chemical polishing of ferrite, and suggestion on the mechanism of mechano-chemical polishing. Such elastic polishing plates as synthetic leather is popularly used with an alkaline polishing fluid in the mechano-chemical polishing of semiconductive materials. In this paper, however, polishing plates made by either tin or lead are used with chemically active polishing fluid to ferrite. Electro-chemical action is added to mechanical polishing for the sake of composing the local cell between a polishing plate and a workpiece. Electro-chemical action not only increases stock removal rate twice or more, but also reduces the surface damaged layer of workpieces a quarter or less in comparison with those in mechanical polishing process.

フェライト材の電圧印加複合研磨法 電圧印加による能率向上

This paper presents some experimental results on mechano-electrochemical polishing with applied voltage and suggestion on the mechanism of this polishing. In polishing of ferrite with stannum plate and diamond-slurry-mixed hydrochloric acid to build up the inner cell, electrochemical action adds to mechanical action. This electrochemical action is accelerated by applied voltage between stannum plate and ferrite. In this case, stock removal rate of ferrite is increased to four times that without applied voltage or to tweentieth times that of mechanical polishing. Morever, surface damaged layer of ferrite is reduced to one tenth that of mechanical polishing.

Hydro-magnetic grinding properties of magnetic fluid containing grains at high speeds

The acrylic resin bar was ground at 10000–60000 rpm with magnetic fluid containing abrasive grains. The stock removal rate was observed as a function of grain size, grain concentration, material of carrier liquid and grain. Optimum conditions of grinding speed, magnetic fluid, grain and a grain concentration were shown.

トラバース研削における形状生成過程

The purpose of the paper is to theoretically calculate infeed of grinding wheel for forming a cambered workpiece such as roll in traverse grinding. The infeed of grinding wheel has been analyzed considering various residual stock removals, wheel wear, the profile change of cutting surface of wheel caused by wheel wear. Then it is made clear that cambered workpiece can be ground with NC-grinding machine. The distributions of stock removal rate, grinding force and wheel wear rate on cutting surface of wheel are calculated.

超音波研削装置の試作とその加工特性 硬ぜい材料の高能率研削に関する研究 Ｉ

As a basic study to establish high efficient machining processes of brittle materials such as fine ceramics, the trial construction of an ultrasonic grinding machine is done and the machining characteristics of this equipment is considered with soda glass. Because of high stock removal rate in ultrasonic grinding, this method proved to be efficient for brittle materials. The stock removal rate becomes higher in accordance with the increase of loading weight, amplitude of ultrasonic, wheel speed and so on.