Spoluautoři PETRŽELA Jiří, KOŘÍNEK Lubomír, SUŠOVSKÝ Michal

The company of Vítkovice Heavy Machinery a. s. (VHM) has significant experiences with the production of various types of forgings, which are delivered to the whole world. However it´s appropriate to make an evaluation of process and find savings when introducing a new product into production or in case of rationalization of the product process itself. These savings may be due to reduction of production scrap (or necessary repairs on the product), reduce the time for production, possibly reducing the amount of material needed to manufacture etc. In this paper we describe the optimization of production of the forging with a flange. We have focused on reducing the occurrence of defects in the flange region. These defects were recorded after quenching of the forging through ultrasonic examination in the area of the flange around the perimeter of the inner hole of the forging. Since the resolution of this problem should led to considerable improvement of the economic situation in the manufacture, it was decided to analyze the overall production process. This analysis consist of detail description of production, metallographic analysis in the affected area, magnetic and penetration testing, measurement of hardness and residual stress of the forging and also in mathematical simulation of quenching including the quenching with segregations. On the basis of this analysis were proposed measures, which should eliminate the occurrence of these defects (without increasing of production costs).