Influence of Viscosity of Base Oil on Effect of Additive in Cutting Oil for Hobbing.

Abstract

It has been already reported that EP additives used in cutting oil for hobbing exert a notable influence on hob wear. However, systematic studies on the effect of the viscosity for cutting oil and on the effect of the viscosity of base oil on action of additives are rather rare. Since there exist generally interactions between an additive and a base oil, the difference in the viscosity of base oil should affect action of an additive. Therefore, finding optimum viscosity conditions in which hob wear and finished surface roughness of gear are minimized, will be necessary for obtaining a standard for selecting or designing an appropriate base oil for additive. From this viewpoint, the effect of viscosity of base oil, moreover, the effect of additive in base oil with a variety of viscosity on hob wear and finished surface were investigated in this paper. Experiments were carried out with a single fly tool. Hob wear tends to be smaller with higher viscosity of base oil. The viscosity of base oil hardly affected finished surface roughness. Among the additives used, the chlorinated fatty acid ester added to the high viscosity base oil showed a best performance and the optimal content of chlorine was 3%.