The control of the coolant flow has a direct influence on the tool life or cutting performance in high speed machining of difficult-to-machine materials. In this paper, the coolant jet was applied to the tool tip from a small size nozzle on the side of flank face during turning and coolant flow was changed by making a groove on the tool flank face. Triangular types of grooves with different groove depths were made on the tool flank face. These groove were designed for reducing the flank wear near the depth-of-cut line. The work material was type 304 stainless steel and the tool used was a cemented carbide insert of M35 grade with a single coating layer of titanium composite. A high cutting speed of 300 m/min was selected and the coolant pressure was 0.3 MPa. It was found that coolant jet was much better in reducing tool wear than flood coolant. Combination of a triangular groove and coolant jet was very effective in reducing tool wear. There was the optimum distance from the depth-of-cut line to a groove. However, groove depth had neither positive nor negative effects in wear reduction. The computational fluid dynamic analysis of coolant flow was conducted for five inserts with triangular type grooves. Particleworks, one of codes for smoothed particle hydrodynamics was used for the analyses. Although it was not easy to indicate a definite relationship between the flank wear and parameters of flow of coolant using a small number of calculation and experimental results, coolant flow analysis could contribute to the improvement of tool face topographies, which are very effective in reducing tool wear under the jet cooling conditions. [ABSTRACT FROM AUTHOR]
incremental microforming, ultrasonic spindle, shin shell micropyramid, metallic foil, forming limit, shape accuracy, Mechanical engineering and machinery, and TJ1-1570
Single point incremental forming is used for rapid prototyping of sheet metal parts. This forming technology was applied to the fabrication of thin shell micropyramids of aluminum, stainless steel, and titanium foils. A single point tool used had a tip radius of 0.1 mm or 0.01 mm. An ultrasonic spindle with axial vibration was implemented for improving the shape accuracy of micropyramids formed on 5–12 micrometers-thick aluminum, stainless steel, and titanium foils. The formability was also investigated by comparing the forming limits of micropyramids of aluminum foil formed with and without ultrasonic vibration. The shapes of pyramids incrementally formed were truncated pyramids, twisted pyramids, stepwise pyramids, and star pyramids about 1 mm in size. A much smaller truncated pyramid was formed only for titanium foil for qualitative investigation of the size reduction on forming accuracy. It was found that the ultrasonic vibration improved the shape accuracy of the formed pyramids. In addition, laser heating increased the forming limit of aluminum foil and it is more effective when both the ultrasonic vibration and laser heating are applied.
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. [ABSTRACT FROM AUTHOR]