Masashi Yamaguchi

Influence of Coolant Application Direction on the Cutting Performance of Ceramic Tool in High-Speed Air-Jet-Assisted Machining of Inconel 718

This paper describes the high speed air-jet-assisted machining of nickel-base superalloy with a SiC whisker reinforced alumina insert. This machining method showed already good performance in high speed machining of Inconel 718. In this paper, the influence of the application direction of coolant on the tool wear and tool life was investigated for obtaining much better cutting performance of the ceramic tool. The coolant was applied from the side of flank face with three different directions: two oblique directions from the end and side flank faces and the perpendicular direction to the cutting edges. In contrast, the application direction of the air jet was always perpendicular to the cutting edges. The experimental results showed that the best performance in the air-jet-assisted machining was obtained by applying coolant from the side of side flank at a cutting speed of 420 m/min and from the side of end flank at a cutting speed of 780 m/min. The necessary condition found for the best performance was that the size of notch wear was a little larger than that of flank wear.

Wear Characteristics of Cutting Tools in Turning of Sintered Steel under Different Lubrication Conditions

Finish machining of sintered steel is increasingly important for near net shape technology. However, the life of a cutting tool for machining sintered steel is generally much shorter than for carbon steel and thus, finish machining increases the manufacturing cost of sintered products. For this reason, wear characteristics of several grades of cutting tools in turning sintered steel were investigated under different lubrication conditions. As a result, it is found that a P10 grade of cermet and an S01 grade of AlTiN coated carbide are recommended for dry machining. When cutting fluid is necessary for chip control and disposal, air jet assisted wet machining with a K10 uncoated cemented carbide and wet machining with a P10 cermet are recommended. It is also found that a small amount of cutting fluid remained in the workpiece during wet machining caused an intense thermal impact to a P10 uncoated cemented carbide leading to short tool life.