Abstract
At high cutting speed, the mutual diffusion of material element between the chip and the tool has a great influence on the crater wear on the tool face.
The purpose of this paper is to study the mechanism of crater wear under high speed cutting by the static diffusion test. So as to find out the relationship between diffusion amount and crater depth, the machining tests and diffusion experiments were carried out by the combination of cermet tool and plaincarbon steel. In the diffusion test, the test pieces were kept for six hours in vacuum at various temperatures from 1188 K to 1380 K.
The diffusion elements were measured by EPMA, and their amounts are represented by X-ray integral intensity factor. The mean free path of the compound carbide in the tool was measured by using SEM image. Machining tests were conducted on a lathe, and cutting speed was varied from 1.3 m/s to 6.7 m/s but depth of cut (2.5 mm) and feed rate (0.25 mm/rev) were maintained constant throughout the tests.
The main results obtained are as follows:
(1) The cutting temperature at high speed cutting has a great influence on the crater wearing rate. A correlative region between crater wearing rate and cutting temperature is under the control of diffusion wear.
(2) Ni in the tool and Fe in the workpiece diffuse the most in amount. The crater wear on the tool face progresses by the mutual diffusion of the material element.
(3) The decrease of mean free path between carbide grains restrains mutual diffusion, and the wearing rate is diminished.
