OF SLEWING RINGS
DISTITEC’S slewing rings have the following technical features:
Outer and inner rings made mainly of C45 carbon steel (UNI 7845) or 42CrMo4 alloy steel (UNI 7846), both in the initial reclaimed condition. The use of a material or another depends on the required mechanical characteristics, including resistance and hardness, but also on technological factors. The 42CrMo4 provides higher thickness of the hardened layer of the rolling tracks, and so higher bearing capacities. The C45 (or equivalent) is the material in which most standard bearings with medium-small diameters are built; the 42CrMo4 is used for medium-large diameters as well as many special executions. The induction hardening to which the sliding tracks are subject is necessary to increase the bearing capacity and to protect the tracks from plastification effects caused by the contact pressure with the rolling elements. After this treatment the hardness of the sliding tracks of the rolling bodies can be as high as 62 HRc. The hardening thickness varies depending on the size and therefore on the loads to bear.
Rolling elements: the balls, built according to DIN 5401, are used for bearings with four contact points, whereas the cylindrical rollers, built according to DIN 5402, are used for crossed roller bearings. Both are made in 100Cr6 core hardening steel (UNI 3097). The hardness of these elements reaches 64 HRc.
The distance rings: are made in materials with high mechanical characteristics such as Nylon or P.T.F.E. (Teflon). They are used to keep the rolling elements separate, thus avoiding the contact between them. Distance rings may not be included in applications where the accepted loads of the slewing ring must be high.
The seal rings or O-rings are produced in NBR nitrile elastomer. The seal rings prevent the introduction of dirt, dust and humidity. The proper lubrication increases the effectiveness of the seal.
Grease: the slewing rings are supplied with the initial lubrication of the ball or roller sliding track. The use and maintenance manual we provide with the products gives information about the specific grease used as well as the instructions for the proper periodic lubrication.
Greasers: Distitec’s slewing rings are supplied with the dedicated greasers, located in the housings along the diameter where the toothing is not present, or where required by the client in case of special executions.
Straight tooth cylindrical toothing (see photo): this toothing is executed in compliance with all the relevant technical requirements. The parameters related to the toothing are marked on the drawing released by Distitec, In order to enable the correct execution of the pinion that will mesh with the toothing. The standard surface hardness of the reclaimed material being used can be as high as 30 HRc (42CrMo4); this hardness value may not always be acceptable to preserve the toothing life in some applications. It may be advisable to execute the induction hardening treatment on the toothing too in the presence of some conditions, such as a high rotational torque which generates high strain and friction on the tooth, high rotational speed, unfavorable environmental conditions with presence of dust or other abrasive elements, or the need to extend the life cycle of the slewing ring as much as possible. The treatment can be executed only on the side or on the side and the bottom of the tooth, according to the loads and the application type. The maximum surface hardness that can be reached is 60 HRc.
For more detailed information about tolerances, normal or reduced clearances, surface treatments etc, please refer to the dedicated catalogue of slewing rings or contact our technical department.