7 th INTERNATIONAL MULTIDISCIPLINARY CONFERENCE Baia Mare, Romania, May 17-18, 2007 ISSN-1224-3264 ABOUT FLANK SURFACE QUALITY IN HIGH PRECISION PUNCHING OF TOOTHED GEARS Lucian BUTNAR 1 , Mihai BANICA 2 1 Associate professor PhD., 2 Lecturer, PhD., North University of Baia Mare, Romania Abstract: The high precision punching is a modern procedure in order to obtain high quality cylindrical gears. During the process, the prominent plastic deformation and the superior tensions produce a flank surface with low roughness. The smooth zone proportion from the processed surface is bigger in high precision punching (about 80-90%) than in ordinary punching (about 30-40%). If the influence factors - quality: material, thickness, clearance and friction - have optimal values, and the proceeding technology is correct, the flank roughness arrived to R a = 0.2…0.4 μm and the toothed gear has a precision in IT 6 – 8 ISO. Key words: high precision punching, influence factors, flank surface. 1. INTRODUCTION The high precision punching is a modern, high-tech and productive manufacturing procedure, which is applied with success for various pieces forms. The high precision punching can be used with success for the obtaining of external or internal cylindrical gears on final size, starting from table semi-product. The gears must be with straight teeth, low thickness (maximum 16...20 mm) and with high precision requirements, used especially in fine mechanics mechanisms and which have varied tooth flank form. The gears are made of punching steel if their width (table thickness - g) is ( ) n m g • ≤ 25 , 2 ... 9 , 1 (1) where is the normal module. n m The principle of high precision punching consists in decreasing the clearance j between the punch-active plate clearance trough negative values or previous pressing with pressures next to the flow limit. The punch and the active plate are teeth contour, of course. ( g 2 , 0 ... 05 , 0 b 8 g j 2 ⋅ ≅ ) ⋅ = (2) where b is the breadth of deformed zone of material.