Slewing bearing materials and heat treatment

According to the application conditions, Fenghe slewing bearings are provided with different material qualities. For slewing bearings with light loads, we use 50Mn material, which is suitable for transmitting bearing and radial forces in most cases. For the high load slewing bearing, 42CrMo material is selected. These steels are able to transmit greater radial force and also provide higher notched impact strength at lower temperatures. In addition to these standard materials, we process specially designed high grade steels. In addition to the basic heat treatment of the slewing ring (that is, normalizing and tempering), Fenghe slewing ring is always made of inductively hardened raceways. Induction quenching ensures good repeatability of quenching specifications, ensures stable quality and prolongs the service life of bearings. By inductively quenching, a hardened marginal layer, just a few millimeters thick, is formed, which has a much higher carrying capacity compared to the original material and improves durability. This layer is the foundation on which the static load limits mentioned in the limit load diagram can be safely transmitted. For technical reasons, induction hardening can cause the unhardened area in the raceway to become smaller. The soft area is clearly marked with the word “S” engraved on the bearing ring of the slewing ring. Gears may be inductively hardened by toothed or single-toothed sector gears if high stress is required under certain conditions. Both methods increase the load capacity of the gear and the strength of the tooth root. After selecting the material, all the inner and outer rings of the slewing bearings go through a series of production steps. From surface roughing to forming of outer and inner gears to drilling and induction hardening, our slewing bearings are machined to customer requirements and can be treated with special finishes prior to final quality checks.