In heavy mining and building materials machinery, a large number of large gear pairs with open drive are used. The gears are not enclosed in the box, so lubrication can not be guaranteed, such as the open drive gears on cement kiln and cement mill. The main damage of this kind of gear is wear, sometimes there will be some gluing or plastic deformation. As long as the hardness of the tooth surface is increased, the service life can be improved. It is an ideal heat treatment method to use flame surface quenching method on site.

ZHY gear has carried out on-site flame tooth surface quenching for open gear of ball mill in six cement plants. The hardness of tooth surface is about hrc45, and the service life is increased from 2 years to 10 years.

If the medium frequency gear surface quenching is used in the manufacturing of the open gear, the service life can also be improved. But special attention should be paid to the fact that this kind of large open gear is mostly composed of two semicircular gears. If it is folded and transported to the site after medium frequency quenching, it may be deformed and can not restore the original accuracy, and can not be corrected and installed.