Investigation of cuttting forces and tool wear on hobs

Although there are a lot of methods for making gears, hobbing is the most common method. In this study, investigation of relations of cutting parameters with cutting forces, tool wear and wear mechanism, surface roughness of gear teeth occurred on hobs at real manufacturing conditions of hobbing has been aimed. Gear samples made from SAE 8620 were machined by using TiN coated and uncoated hobs, in machining tests. For the measurement of cutting forces, an experimental setup which consists of KISTLER 9272A dynamometer with four components (Fx, Fy, Fz, Mz) and equipments was designed and manufactured. Additionally, ANOVA (Analysis of variance) tests of experimental results were carried out using MINITAB R14 software.According to experimental results; it was determined that cutting forces could be measured using the experimental setup designed and made. Main cutting force of Fz was more sensitive to variation of cutting parameters. The coated hobs provided ratio of 59 % decrease on cutting forces. The coating is the most effective parameter on flank wear. Effective wear mechanism on tool wear is the form of combination of several mechanisms (adhesive + diffusion + thermal and/or mechanical fatigue + a little abrasive). The lowest value of mean roughness was obtained at high cutting speed and low feed rate. The results obtained in this study that were performed in real manufacturing conditions provided important benefits to understanding of hobbing operation and evaluate the relations between hob and gear.