Research on Ultra-high Precision High Speed Machining of Steel

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The objectives of the research are to prove the feasibility of ultra-high precision machining of the steels including the stainless steel and to contribute for further development of the relevant technologies. Experimental investigations were carried out on the ultra-precision fly cutting of the steels with CBN tools from the viewpoints of the chip formation, the surface integrity, the cutting forces and the wear and failure of the tool etc.. The major results obtained are as follows;1. Chip formation and surface integrity in ultra-high precision micro machining of steel The Ultra-high precision micro machining of stainless steel (JIS: SUS303Se) and carbon steels (JIS: S45C and S25C) were carried out with specially ground CBN tools and the chips were formed at small depth of cut down to 1 to 2 <mu> m. The surface roughness of less than 0.1 <mu> m in Rmax was obtained in the case of the stainless steel.2. Cutting forces in ultra-high precision micro machining of steel The thrust force was found to be maximum among the three force components within the range of experiments carried out. The second largest component was the main cutting force and the feed force was smallest. The ratio of the thrust force over the main cutting force was 1.6 to 2. The cutting forces do not depend much on the cutting conditions. The nominal specific cutting force calculated based on the theoretical cross sectional area of cut was found to be increased extremely at reduced feed rate.3. CBN tool and ultra-high precision machine tool It was found that the contents of CBN in the CBN tool much affect the failure resistance of the tool in fly cutting of the steel. The binder of the CBN tool also plays an important role. The rigidity of the main spindle of the ultra-high precision machine tool influences the tool life.