Abstract
The hobbing finish of hard gear tooth surfaces such as case-hardened gears is expected to be put to practical use for high efficiency production. This paper investigates the properties of wear and finished surfaces by the hob cutter made with cubic boron nitride (cBN) in high speed cutting at 900m/min of case hardened steel. The content rate of cBN in the tip ingredients relates to the wear rate, and high content cBN tips are superior to the wear resistance. High thermal conductivity of cBN tips contributes to the heat transfer of cutting temperature to chips, resulting in melting and adhesion of chips on the relief surface. Flaking wear on the cutting edge sometimes occurs and chippings do not occur newly though chippings exist after grinding. The finished surface roughness is influenced by the horning figure on the cutting edge. Round horning of the cutting edge leads to the smooth surface. Possibility of high speed finishing with cBN-tipped hobs is discussed by a point of view of grinding of cBN tips and properties of the finished surface in addition to wear properties.
