This paper presents application of the candlestick drill with a convex cutting edge at the drill corner for drilling unidirectional carbon fiber-reinforced thermoplastic (CFRTP). The influence of the angle between the cutting direction of the continuously changing convex cutting edge and the fiber direction on the cutting characteristics was considered in terms of cutting force, hole quality, and cutting temperature. The cutting characteristics of the candlestick drill were compared with those of a conventional drill with the convex cutting edge removed. The thrust force of the candlestick drill was higher than that of the conventional drill at all drill rotation angles. The point of the convex cutting edge was thin and sharp in the axial direction and was involved in the cutting process before the corner of the main cutting edge, such that chips flowed independently of the main cutting edge. The quality of the drilled hole obtained with the candlestick drill was better than that obtained by the conventional drill.

Hobbing is the most frequently used method for gear production. A simple fly cutting experiment was conducted by simulating hobbing on a milling machine to examine the relation between cutting mechanism and tool life. However, this method differs in some respects from actual hobbing. A new method of tool wear testing similar to hobbing was proposed. This new method was also useful for measurement of cutting forces and cutting temperature. Experiments were performed with TiN-coated and non-coated tools. The results showed that cutting forces and cutting temperature were smaller for the TiN-coated tool than the non-coated tool. In addition, the TiN-coated tool showed less adhesion of chips than the non-coated too