SELF-LUBRIFICATING BUSHINGS multilayer with composite PTFE
Also defined by the term DRY BEARINGS thanks to their layer of Ptfe, they group in themselves various advantages:
• They are maintenance-free
• Ease of assembly
• They have good friction properties with low wear and high load capacity
• High creeping speed
• Very high working temperature range
• Negligible stick-slip effect
• Content operation game
• Good chemical resistance
• Low oil, water and bulge absorption
• Inert to most chemical gases and solvents
• Does not store static electricity
They consist of a low-carbon steel armature that gives mechanical strength and coated externally with 2μm of copper or other protective treatment. Internally a layer of sintered porous bronze on the wall ensures a good adhesion of the PTFE layer to the steel. They can be mechanically processed, except in the creeping surface except for any ducts to slide the lubricating oil. These bushings can have a protective treatment on the outer surface in copper, tin or zinc (the latter for example also suitable in the structures of the awnings) which protects the bearing from oxidation and corrosion. This product is ideal for versatile design.
It is also possible to have bronze (amagnetic) or stainless steel walls.
In the initial running-in phase a part of the Ptfe is transferred to the contact surface creating a lubricating film that allows low friction without lubrication. Discrete incorporation of abrasive substances, excellent operation with oil that in addition to lubricating subtracts heat from the sliding surface by extending the life of the bushing. On the other hand, it is not recommended to use grease that tends to make the Ptfe detach if not maintained regularly. Do not use MoS2-based additives.
The sectors are the most varied: from hydraulics, to household appliances, to the automotive industry (hinges, shock absorbers, pedal boats, etc.), 3D printers, motorcycles, the pharmaceutical, food and gymnastics equipment sectors. Especially indicate where there are high loads and medium low speeds even oscillating.
The bushing shall be mounted by interference with the junction zone opposite the direction of the load, using a stair spindle and providing for invitation chamfers of 15°/20° on the H7 tolerance seat, while the shaft in tolerance f7 (over d.75 = h7) is recommended for hardness HB 300 ÷ 600 with a roughness less than 0.4 μm (in the case of cast iron 0.3 μm). If necessary for fixing it is possible to use synthetic adhesives.
PTFE/Fibre mixture thickness 0.01~0.03mm, provides an excellent initial transfer film, which effectively coats the mating surfaces of the bushing assembly, forming an oxide type solid lubricant film. Sintered bronze powder thickness 0.20-0.35mm,provides Max. thermal conductivity away from the bushing surface,also serves as a reservoir for the PTFE-Fibre mixture.
SL: Low-carbon steel,gives exceptionally high load carrying capacity, excellent heat dissipation. Copper/Tin plating thickness 0.002mm, provides good corrosion resistance.
SLB: Bronze backing, provides exceptionally high load carrying capacity, excellent heat dissipation and very good corrosion resistance.
SLSS: Stainless steel backing, provides very good corrosion resistance.