Plain bearings

MAINFREE© sliding materials

Due to the particular orientation towards a high abrasion resistance, the sliding layer of the Mainfree© brand is configured to an extremely tough steel base with high manganese content. Depending on the acting wear mechanisms, user-friendly structural conditions are added to different grades of austenitic manganese steels. The combination of material matrix with defined hydromechanical/vacuum-supported heat treatment and surface techniques aims at a sliding layer with the necessary optimal relation of the hardness gradient to the toughness.
Laboratory and field tests show that hard and tough Mainfree hard manganese steel structures is superior to a conventional forged structure of X120Mn12 from a sliding tribological point of view.

Particular sustainability aspects:  Download of our publication "Stahl und Eisen"

MAINFREE plain bearings are particularly suitable in cases where the exposure to dust and dirt is unavoidable and the dominant wear process is characterized by abrasion. The wear remains in the lower shelf even in ambient media with a wide spectrum of abrasive grain hardnesses and sizes. In defined p•v zones, the operation is possible without lubrication, even at higher temperatures. Typical application areas are bearing conditions which make a lubricating and/or sealing function ineffective, with a simultaneously high impact and shock load.
An impressive example is the application in the ladle metallurgy in a German steel works. Without lubrication, it is possible to achieve a considerably longer service live compared to the previous intensively lubricated journal bearing with a red brass alloy.


The plain bearings of austenitic manganese steel brand MAINFREE

  • have an excellent resistance to abrasion wear
  • show a high safety against rupture and are shock and impact resistant
  • have a specific grain arrangement and compaction with hardness structure of 500 HV
  • can undergo a hydro-mechanical strain-hardening up to 700 HV, depending on the application
  • can be operated without maintenance
  • are dynamically resistant up to 60 MPa.
  • can be used at operating temperatures of up to T=400°C.


In applications with additional tribooxidative wear mechanisms, specific corrosion-proof Fe-Mn-N grades have proved to be successful. The mechanical properties are superior to the MAINFREE grade so that higher contact pressure will be achieved. However, the axles must have superior values regarding strength and hardness.


In case of certain applications, which require maintenance-free operation, acoustic emissions might occur.
Molybdenum disulfide or graphite inserts allow a reduction of the friction coefficient preventing the noise effectively.

Counter bodies in the tribological system with MAINFREE plain bearings

The axle/wave counter bodies should consist of induction hardened heat treatable steels or of case-hardened or carbonitrided steels. Through-hardened axles made of rolled or cold work steels are also possible, if a hardness of 57-60 HRC can be achieved.

Application areas

Iron and steel industry

  • ladle journal bearings - maintenance-free/low maintenance
  • billet-, slab tongs
  • scrap cranes | bucket loaders | transportation of slag
  • Conveyor and apron conveyors | roller conveyor bearings
  • Continuous casting rolls | dummy bar chain
  • Pivot joint bearings in dusty environments

Cement and recovery industry, mining

  • winning machines
  • excavator shovels
  • replacement of chain link bushings of X120Mn12 with 70 % less friction
  • MAINFREE joint bearing for maintenance-free hydraulic cylinders underground

Building industry

  • accessory equipment
  • underwater grippers
  • waste grippers
MAINFREE (application)MAINFREE (application)
MAINFREE (application)MAINFREE MAINFREE (application)