Study On Cutting Performance Of Coated Cemented Carbide Tools

Because of its high hardness, good wear resistance, excellent thermal stability and applicability, the coated cemented carbide tool is now widely used in metal-cutting area and becoming one of the most ideal cutting tools to research and develop around the world. Compared to other countries, the research about coated cemented carbide cutting tool still stays at a relatively low level in china, especially, the research on cutting performance of MT-CVD and TiAlN coating cemented carbide inserts is rare to see in the current literature. In order to have a better understanding about differences between these two kinds of coating and to estimate the shortage between homemade and imported coated inserts, a series of comparison experiments with the 1Cr18Ni9Ti austenitic stainless steel workpiece were carried out, using 4 types of inserts home and abroad.Firstly, the effects of cutting parameters on cutting forces were studied, and the cutting forces of the inserts were compared .The results indicated that the radial cutting force was higher than the main cutting force at lower feed rate and cutting depth; and with the increasing of cutting speed, the cutting forces increased first and then decreased when GC2025 and YBC251 inserts were used, while the cutting forces of GC1025 and YBM252 inserts just declined along with the cutting course. Generally speaking, the cutting forces of imported inserts were relatively lower than that of homemade ones coated with the same materials.Secondly, according to the orthogonal experiment of cutting austenitic stainless steel, the influence of cutting parameters on surface roughness of the workpiece was analyzed. The results showed that the feeding rate was the most remarkable influence factor and the effect of insert type, cutting speed, cutting depth and cutting fluid declined in succession. Subsequently, the influence of cutting parameters on the deformation rate and the microscopic characteristic of chips were also analyzed. It was revealed that, the cutting speed and the feed rate greatly affected the deformation rate, while the cutting depth had an insignificant influence on it. And it was found that one side of the chips' microscopic appearance was serrated structure; while the other side was smooth banded but asymmetry structure.In the end, tool life and abrasion of the four types of inserts, as well as their wear mechanism, were analyzed. And the microstructure differences between two kinds of MT-CVD coated inserts were also studied. Conclusions were drawn as following YBM252 insert which has PVD coating enjoyed a much longer cutting life than YBC251 by CVD method coated, and the imported inserts GC2025 and GC1025 have a remarkable longer cutting life than homemade inserts YBC251 and YBM252. Moreover, GC2025 have a multi-layer coating and the gradient cemented carbide substrate rich in Co, while YBC251 adopt traditionally multi-layer technology on the normal cemented carbide substrate.