This study represents some characteristics of the path interval formula proposed previously in multi-axis filleted end milling. The path interval is known as a machining condition to consider a suitable balance between manufacturing efficiency and machined surface quality. However, the practical formula has not necessarily been provided for multi-axis filleted end milling. With reference to the formula proposed in our previous report, the some characteristics were numerically investigated only when the tool inclination was set along feed direction. In addition, the revealed characteristics were further elaboratively compared with those of several end mills. As a result, the novel formula was more effective for path interval determination in filleted end milling.

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Carbon fiber reinforced thermoplastics (CFRTP) have superior material properties, including light weight and high strength. In addition, CFRTP can be easily recycled and shows high molding speed. However, CFRTP is known as difficult to cut material. The problems of machining CFRTP are short tool life and burrs. In this study, side milling tests are carried out with changing of the coolant (Dry/LCO₂). Cutting force, surface integrity, tool wear, and cutting temperature are examined. The elastic module of matrix resin (PA66) under cryogenic conditions is higher than that under dry conditions. The results indicated no significant difference in tool wear between dry and cryogenic conditions. However, the use of cryogenic machining improves the surface integrity and suppresses burrs.

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When processing microshafts by turning, the thrust force causes flexural deformation of the workpiece and adversely affects machining accuracy. A method for minimizing the thrust force was proposed. The aim of this study is to predict the thrust force-free cutting conditions theoretically. When the feed rate is comparable to the cutting edge radius, the cutting edge radius has a marked effect on the cutting mechanism and the minimum uncut chip thickness (MUCT) is not negligible. By considering the MUCT, the accuracy of the cutting force prediction was improved.

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