ZFO-Cu sliding materials
For economic reasons and ecological responsibility, bronze and brass bushings should and could be substituted by efficient steel plain bearings. Due to the expected great demand for copper from the electromobility and the alternative energy conversion area, a jump of the copper price must be considered in the medium term, besides the already high price volatility.
However, in special cases of application, Cu-based bearings with alloying elements like Sn, Zn and Al may be favourable.
Aluminium bronzes have, e. g., an excellent corrosion resistance in seawater environments. Depending on the bearing requirements and the friction and wear mechanisms, we specifically use Cu alloys with different chemical composition. In order to improve the friction conditions in the sliding joint, we recommend a specific groove system based on a rhomb-geometrical network comprising the whole sliding surface, different characteristics, e. g. in the Smart design.
The plain bearings of the ZFO-Cu brand
- have a high resistance to tribooxidation and adhesion
- are corrosion-resistant
- AI alloy makes them particularly suitable for seawater applications
- are highly resistant to static and dynamic stress in a corresponding composition
- allows cost-effective production due to robot interfacing CNC manufacturing
Measures for sustainability effects
“Solid lubricant clusters” introduced in the functional surface, with sliding lacquer overlay, if necessary, from substances with hexagonal lattice structure, reduce the friction coefficient permanently. The bearings can be operated without lubrication and thus without maintenance. Depending on the load, direction of force, sliding speed and temperature, selected Cu compositions are combined with groove systems in such a way that hard particles are embedded and the resistance to abrasion is increased.
By introducing aluminium and/or zinc alloy, Cu compositions are reached which have a great wear resistance during mechanical stress.
Very high static and dynamic contact pressures regarding applications with swivel movements can be realized with our special brass based on CuZn25Al5 and CuZn34AL.
In case of high dynamic stress and the simultaneous requirement of a higher resistance to corrosion, e. g., seawater proofness, aluminium-alloyed Cu materials are the first choice. For these applications, we recommend our copper aluminium alloys according to the CuAl10Ni or CuAl11Ni compositions.
The Cu tin-base plain bearings are designed for medium mechanical stress.
Bearing bushings of this type are intended for the periodically lubricated use in corrosive environments with good wear resistance, mainly to adhesion and tribooxidation. A periodical lubrication is necessary; the bearings have very good emergency running properties and are available in a rolled design.
In ambient media with a high volume of abrasives, the harder ZFO-CuHeavy version is recommended.
Counter bodies in the tribological system with CuL plain bearings
The surface hardness of the axle/wave counter body should be increased by a factor of about 3 in relation to the plain bearing hardness. In case of soft and medium-hard bronzes of 60-70 HB, a natural axle hardness of 220 HV10. A considerable increase of the service life will be achieved at hardnesses exceeding 500 HV10. The fine surface roughness has a significant influence.
Higher service life is achieved if the counter body of heat-treatable steel has a nitrocarburizing layer – as achievable by the layering based on the FIOX process. The FIOX process allows a high surface hardness with lower roughness and it also creates a corrosion protective layer. (See also FIOX combination process)
In case of brasses and aluminium bronzes, the surface hardness should be at least 50 HRC - the steel surface should also be protected against corrosion.
Building machinery, shipbuilding / harbour installations / off-shore
- jib bearings
- various excavator shovels
- mobile crane joints | ship loaders
- capstans | footstep bearings marine propeller
- off-shore - lifting equipment | stub axle bearings
Steel and iron industry
- workshop cranes
- various swivel bearings
- guide bearings also for hydrodynamic applications
- hoisting devices | gear manufacturing
- differential gears in motor vehicles etc.