Yoji Umezaki

Study on the Development of Resource-Saving High Performance Slurry - Polishing/CMP for Glass Substrates in a Radical Polishing Environment, Using Manganese Oxide Slurry as an Alternative for Ceria Slurry

While investigating polishing mechanism of glass substrates with ceria abrasives (CeO2), we found its oxidizing properties worked effectively for the polishing. This finding has inspired us to speculate about the possibility of the manganese oxide abrasives as an alternative for ceria as they also have oxidizing properties. Therefore, focusing on the valence of the manganese, we have experimentally manufactured MnO, MnO2, Mn2O3 and Mn3O4 abrasives, and conducted a comparison study of the characteristics obtained with ceria slurry and manganese oxide slurries. As a result, the surface roughness of below Ra 0.8nm obtained with Mn2O3 slurry was found better than that with the conventional ceria slurry, on top of which, its removal rate was as good as or equal to that of ceria. Using a novel, closed type CMP (Chemical Mechanical Polishing) machine, we conducted another glass polishing experiment with ceria and manganese oxide slurries. The inside of the CMP machine was filled with high-pressure gases such as oxygen, air and nitrogen and kept at 500kPa to make the polishing environment radical. Through this experiment, we found an effective polishing method for high-quality surface. The removal rates were several times better than that of the conventional polishing performed in an open CMP machine.

Polishing Mechanism of Glass Substrates with its Processing Characteristics by Cerium Oxide and Manganese Oxide Slurries

With an aim to reduce the consumption of cerium oxide (CeO2) used in large quantity for the polishing of glass substrates applied for HDD and display, we have attempted to obtain the processing characteristics of glass substrates by CeO2 slurry. We also paid attention to manganese oxide abrasives to replace cerium oxide abrasives. As a result, we have found Mn2O3 abrasives potential to replace disappearing CeO2 for the polishing of glass substrates.

Basic Characteristics of a Simultaneous Double-Side CMP Machine, Housed in a Sealed, Pressure-Resistant Container

We designed and manufactured a prototype of a unique CMP machine, which can perform double-side CMP simultaneously in a sealed and pressure container as regarding effective action of the processing atmosphere around workpieces as important. Polishing experiments with single crystal silicon (Si) wafers (100) are performed by charging the container with various gases. As a result, the removal rates increased by up to 25% under high pressure oxygen gas atmosphere.

Impact of High-Speed Image Recognition of Transition Phenomenon of Chip Formation and Chip Flow in Gear Hobbing Process

The transient phenomenon of chip generations and behavior in the gear hobbing process are investigated by using a high-speed video camera. The chip behavior generated in gear finish hobbing process is very complicated and one can not identify each chip from specified cutting edges. The authors have built up a new simulation method of the hobbing process using a flying tool and a special-shaped workpiece, which consists of one tooth space. Visual evidences of the chip interference on the rake face and some conditions of contact between generated chips and the work surface were visually obtained. In the case of dry cutting conditon with a high-speed steel (HSS) flytool without coating on the rake face, the flytool cuts the workpiece frequently with the stuck chip generated in the previous revolution on the rake face. The newly generated chip pushes out the previous stuck chip, which flies away eventually. The chip flow on the rake face interferes strongly at the corner of the cutting edge when both top and side cutting edges produce different chips at the same time, and the chips flow out in changing the shape. The moving speed of the chip was also measured.

Application of mems technique for micro gear metrology

We try to measure direct transmission of rotational motion between a gear pair, which is called transmission error, without knowing the tooth flank accuracy of each gear. In transmission error measurement, the rotational angle of the shaft of each gear is measured with a pair of rotary encoders. For micro gear engagement, the center distance between a pair of gears is very small, so the rotary encoders have to be small as well as micro gears. A grating disk with a small diameter for a micro rotary encoder must be designed and manufactured. In machining process, one of the MEMS technique is applied. Patterning accuracy is examined in detail.

Transient Phenomenon of Chip Generation and Its Movement in Hobbing : 4th Report, The Relationship Between the Jamming of Chips on the Finished Surface and the Chip Form in Generating in Flytool Simulation Tests(Machine Elements and Manufacturing)

The degradation of tooth surfaces and the abnormal tool wear sometimes occurs in dry hobbing. This paper investigates the transient phenomenon of chip formation and behavior in simulation tests of hobbing by using a high-speed video camera. The jamming of the chip between the tooth surface and the cutting edge causes scratches on the tooth surface and the chipping of a cutting edge so on. The figures of chips produced by hobbing are classified roughly into the “U”, “J” and “I” types. This paper presents findings of the “J” and “I” type-chip movements in flytool simulation tests. The “J” type-chip is removed with the two cutting edges both top and a side edge. In the “J” type-chip, a part of end side of the chip produced by the top cutting edge is often jammed into the finished surface by pushing from the chip at the side cutting edge. The “I” type-chip flows from the root to the tip side of the cutting tooth, and the pointed end of the chip is jammed into the space between the finished surface and the relief face of the cutting tooth, in down cut. In up cut, the chip flows to the root side of the rake face, and possibility of jamming is shown as well as the case of down cut.

Transient Phenomenon of Chip Generation and its Movement in Hobbing (3rd Report, The Relation of the Ending Point of Cut of Chip Movements)

The degradation of tooth surfaces and the unusual tool wear sometimes occurs in dry hobbing. This paper investigates the transient phenomenon of chip generations and behavior in hobbing by using high-speed video camera. The location of the ending point of cut on a cutting edge influences chip movements at the take-off from the tooth flank. Many chips rotate around the fulcrum of the ending point of cut. Some chips produced with the regular cutting tooth flow to the opposite side frequently when the ending point of cut exists at the trailing side in the conventional hobbing. When the chips flow to the opposite side flank, though the chips do not jam into the space between tooth surface and cutter relief surface, the chips strike against the tooth surface. This phenomenon gives suggestions to the degradation of tooth surfaces. In the climb hobbing, the chip movements are similar to the case of the conventional hobbing. However, many chips flow away to the direction of the tool revolution because the both flanks facing each other guide chips at the root just after the end of cut.

A Study on Cutting Forces in Gear Cutting. A Theory of Cutting with Two Continuous Symmetrical Cutting Edges.

In hobbing the cutter has many cutting teeth. Each hob tooth has two or three cutting edges. When a hob cuts a gear, each chip is simultaneously produced with two or three cutting edges of one tooth. Then the interference occurs among the parts produced by those butting edges, and the specific cutting forces become larger than those in orthogonal cutting. In this paper, the interference of chips is theoretically investigated. The simplest model of the interference of chips is the cutting of full-depth or non-full-depth triangular cuts. So the specific cutting forces in non-full-depth triangular cuts with a point nose straight tool are theoretically investigated with various included angles. The result shows that the specific cutting forces become large when the included angle is small. The specific cutting forces with an included angle of 90 degrees are about 1.3∼1.35 times as large as those with a flat tool.