Hidehiko Takeyama

Machining Standards for Turning Normalized Plain Carbon Steels (S55C, S45C, S35C, 525C, 515C)

This report is for the project to establish the machining standards for various important metals specified by the Japanese Standard. The major items of the test are selection of carbide grades, tool shapes, speeds, and feeds for turning typical five grades of normalized plain carbon steels, and close investigation of the tool life from the viewpoint of both flank wear and crater.According to the test result, crater wear is the most serious problem in turning the carbon steels. Therefore, every effort should be made to control crater wear in selecting the best carbide grade, tool shape, cutting conditions, etc.

Velocity Distribution of Chip Flow

The conventional macroscopic treatments of machining theories seem to have reached a deadlock, because many contradictions or discrepancies encountered are considered to be due to the rather rough assumptions in the conventional machining theories. Typical examples are the so-called shear plane and chip-flow velocity. According to the experiment, shearing slips in metal machining would not occur in a simple shear plane, but does in a rather wide zone ahead of the tool. As to chip-flow velocity, it is not uniform along the rake face, but it is very slow near the cutting edge and it increases gradually to reach a definite constant velocity. This paper describes the results of the close investigations of chip flow or chip deformation by means of a special technique.

Machining Performance of Home Made Ceramic Tool (No. 2)

In the foregoing paper, the machining performance, the tool wear process, the economical machining conditions, etc., when machining Meehanite cast iron, with a home made ceramic tool were studied. The conclusion was that the ceramic tool can be successfully applied for machining cast iron from a practical point of view.Here in this paper, the same items have been analysed when machining an alloy steel, while being compared with a carbide tool of a steel-cutting grade. The conclusion is that the home made ceramic tool is not reliable enough to be applied for machining steels. The reason for this seems to lie in its inconsistency due to chipping or brittleness of the cutltng edge.

Cutting Speed Effect in Metal Machining

The conventional machining equations such as 2 φ + μ - α = C cannot tell us which factor is the cause and which is the result in machining characteristic, because the equations were mostly derived by the least energy principle, which is not proper to apply to such a non-conservative system as metal cutting. Furthermore, in these equations the coefficient of friction which has been proved to be meaningless in metal cutting by this report is involved.Another defect of the convetional equations is that they do not represent the effect of cutting speed.The object of this report is as follows :(1) to search for the controlling factor in metal cutting, (2) to clarify the coefficient of friction in metal cutting, by analysing the stress distributions on the rake face, (3) to establish the universal equation which does not contain the meaningless term of so called coefficient of friction, and does contain the term of cutting speed effect (Part 2).The foundation of the theoretical and experimental explanations in this report is focused on the chip-tool contact area, which has been proved to be the controlling factor in metal machining.