抄録
Modern high-speed tools are classified into the following four general groups:-
(1) 18-4-1 series and cobalt high speed steels.
(2) Cemented carbide tools.
(3) Cast tools.
(4) Other series of tools.
In this paper, the writer deals principally with the tools of (1), (3) and (4) series in accordance with his investigation.
The experiments consist of the measurement of the thermal expansion coefficient, microscopic tests, cutting tests and the effect of heat-treatment on the hardness of the tools of (1) series.
The experimental results show that the steel containing 10 per cent of Cobalt and 0·7 per cent of Molybdenum has the most excellent physical and metallurgical properties.
The author attempted to improve ordinary cast tools by using a specially devised apparatus which can compress the tools at a Pressure of 0·5kg/mmmm2 and at such a high temperature as 1, 200°C These compressed tools showed the most superior cutting efficiency and hardness in comparison with ordinary cast tools made of similar chemical composition.
