Investigations on Surface Defects in Gear Hobbing

An important property of manufacturing processes is the process reliability. This refers to the macrogeometry and to the achievable surface quality. In dry gear hobbing as the most productive and common manufacturing technology for the soft machining of cylindrical gears sometimes surface defects are noticed. These defects like welded-on chips and smeared areas on the flank are not acceptable.The mechanisms leading to surface defects are not known and understood in total. For the understanding, first the appearance and exact occurrence have to be investigated. Parallel, metallografic investigations are carried out for the characterization of the defects. Further on, the appearing of surface defects and characteristic values generated by a manufacturing simulation for gear hobbing are compared to find influences of the tool and process design on the tendency of dry hobbed gears towards surface defects.