Papers by Author: Takeshi Akamatsu

Abstract: The results of an investigation on the effects of surface roughness on adhesion to the coating using the assumed tungsten carbide end mill tip with various degrees of rake surface roughness are reported here. The grindstones with varying in grit between #230 and #1500 were used to grind tungsten carbide tips and then coated the tips with TiAlN film, CrSiN film, and TiSiN film. The state of adhesion on the films on the rake surface as well as the surface roughness and cutting resistance were measured in the continuous lathe turning. The results show that, in generating the cutting cutoff, the optimum grinding roughness differs between the near vicinity of the cutting-edge ridgeline and the part of the rake surface that is further away from the cutting-edge ridgeline. From that fact, it can be understood that the cutting characteristics of the work material and the surface area of the rake surface that is in contact with the cutting cutoff exert their respective influences during the cutting.

Abstract: This study investigated adhesion of coatings on a grinding surface. This was carried out using scratch testing as a function of surface roughness. Three types of coatings were explored: TiAlN, CrSiN and TiSiN. With smaller surface roughness, the coating adhesion showed a tendency to become stronger. In particular, in the case of surface roughness under 2 micrometers for a coating, the coating adhesion was good. Specifically, the CrSiN coating yielded a very smooth surface.

Abstract: The machining of metal dies involves a variety of processes that include grinding, polishing and electrical discharge machining in addition to various cutting processes such as turning, boring, and milling. The precise machining of complex dies, particularly in deep machining, has largely been done by electrical discharge machining in the past, because the use of end mills and other cutting tools for such work has been difficult. In recent years, however, problems such as low machining efficiency and the creation of an affected layer have made the use of end mill cutting tools the general approach to this task. In the research reported here, our objective was to establish guidelines for the optimum design of small radius ball end mills for the deep machining of dies by systematic investigation of the cutting tool characteristics, which is to say the rotational behavior, cutting resistance, actual rate of depth of cut and machining accuracy of small radius ball end mills. Here, the guidelines obtained for ultra-deep, highly-accurate machining that is applicable to machining programs and is based on quantitative results for amounts of tool wear and tool deflection that obtained using the optimum tool shape reported earlier are presented.

Abstract: Machining of complex shape and deep micro cavity in die and mold is mostly carried out by electrical discharge machining process. However, it may not be able to sufficiently meet delivery deadline minimization and cost reduction of die and mold. Therefore, precision machining method using small radius ball end mill capable of machining deep cavities in miniature die and mold is proposed as a substitute for electrical discharge machining. This report presents such a result supported by experiment in which it has been proved that long tool life of ball end mill can be maintained by changing coating material and edge profile of small radius ball end mill experiencing form accuracy and get needed surface finish in workpiece. Therefore, for precision machining of die and mold as substitute for electrical discharge machining, it is proposed to perform deep precision machining using small radius ball end mill. This paper shows effect proved by experiment how cutting characteristics which occur by changing of coating material and edge profile of small radius ball end mill influence form accuracy and finishing surface of workpiece.