Kazuki Takafuji

Experimental Study of Cutting Performance and Tool Wear in Dry Side Milling of Aluminum Alloy with DLC-Coated HSS-Co Cutter

This paper presents the experimental results of cutting performance and tool wear of a milling cutter in dry side milling of aluminum alloy A2017. The milling cutter consists of Co-bonded High-Speed-Steel matrix with Diamond-Like-Carbon coating (abbrev. DLC-coated HSS-Co cutter). The machining experiments were carried out under cutting speed of 63 to 189 [m•min-1] and feed of 0.08 [mm/tooth/rev], and the criterion of tool life was the generation of gauge and/or scratch on a machined surface. The experimental results support that the DLC-coated cutter in up cutting has good performance among four types of combination by the presence or absence of coating and the up/down cutting manner. They also showed that the tool life of DLC-coated cutter in up cutting under cutting speed of 157 [m•min-1] was corresponding to the cutting distance of 80 [m] with average width of flank wear 102 [μm] and that in down cutting was 60 [m] with 85 [μm]. In the range of cutting distance up to 100 [m], the resultant cutting force with the DLC-coated cutter was smaller than that with a non-coating cutter. In case of the DLC-coated cutter in up cutting under the cutting speed of 189 [m•min-1], a chatter vibration occurred during the initial cutting distance. In case of the radial depth of cut of 1.5 [mm], it lasted up to the cutting distance of 10 [m] and more.

Experimental Characteristics of Aluminum Alloys in Dry End Milling

This paper describes the cutting characteristics of aluminum alloys in dry end milling experimentally. The tested materials are A1050, A2017, A2024, A5025 and A7075. The cutter is a flat end mill of Co-cemented High Speed Steel with the diameter of 20 mm. Through the experimental results of side milling, the following three aspects have been found out. Firstly, as to the machining error, A1050 showed smaller machining error than 15 μm in the cutting speed rage from 62.8 m/min to 251.3 m/min. Other Aluminum alloys showed greater values. Secondly, as to the cutting force, those of aluminum alloys except A2017 were generally proportional to their material hardness. The cutting forces of A1050 and A5052 were constant over the whole range of cutting speed. Thirdly, as to the machined surface roughness, A7075 showed the smallest surface roughness among the all materials with its arithmetical mean roughness Ra under 0. 2 µm and with its maximum height of profile Rz under 1 μm. The machined surface roughness of A2017 varied widely. Through the visual inspection of machined surface, A2017 and A2024 showed picked surface as generated by a built-up edge. This document explains and demonstrates how to prepare your camera-ready manuscript for Trans Tech Publications. The best is to read these instructions and follow the outline of this text. The text area for your manuscript must be 17 cm wide and 25 cm high (6.7 and 9.8 inches, resp.). Do not place any text outside this area. Use good quality, white paper of approximately 21 x 29 cm or 8 x 11 inches (please do not change the document setting from A4 to letter). Your manuscript will be reduced by approximately 20% by the publisher. Please keep this in mind when designing your figures and tables etc.

Static and Dynamic Performance of High Stiffness Hydrostatic Thrust Bearing by Movable Land

In the high stiffness hydrostatic thrust bearing in which the land supported elastically could displace instead of shaft movement against load fluctuation, a new elastic supporting construction without friction while land displacement is proposed. With regard to the static performance, this bearing shows infinite stiffness within the load carrying capacity of 0.4 to 0.9 under the optimum condition and this agrees well with the calculated results. Meanwhile, the self-excited vibration takes place sometimes in this bearing for the lowering of damping capacity. The stable region for the vibration is examined and the factors which influence it are clarified. Then in order to suppress the self-excited vibration, a squeeze film damper which does not affect the static performance is installed inside the bearing body. By this damper, stable operation under the optimum condition becomes possible with the proper matching of the squeeze clearance and oil viscosity or oil temperature. The effect of the damper is also confirmed by the stability analysis.