Coatings are lubricants that are applied to a surface as a coating. There they form firmly adhering, dry lubrication films with high effectiveness. They consist of solid lubricants and organic or inorganic binders as well as a solvent. As well as the main components, they can contain functional additives such as corrosion inhibitors or ultraviolet additives. MoS2, PTFE or other synthetic lubricants are the most frequently used ones for solid applications.
Coatings are used in all sectors of industry. Their importance is constantly growing due to increasing automation in manufacturing and assembly. It is not uncommon that the use of coatings replaces various lubrication processes in a workflow. For example, parts for installation can be transported and protected against corrosion and soiling with an anti-friction coating. The coating used then replaces a liquid or solid assembly lubricant or a mechanical aid for the assembly.
Coatings are being used more and more frequently for supporting the running-in processes of machine elements. They provide additional protection against wear, have a defined friction coefficient and make the entire process more predictable and more reliable.
In many cases, coatings make lifetime lubrication possible and enable simpler designs compared to those using conventional lubrication.
Thanks to their versatility, easy handling and application, coatings are used in numerous manufacturing processes in almost all areas of industry. The applications include sealing lips, locking systems and cylinders, springs, camshafts, gearboxes, spindles, sliding bearings, O-rings, door, window and boot seals, valves, hinges, switches, screws, bolts, chain elements, sintered metal sleeves, bearing shells, linear guides, toothed racks, valves, carburettors, pumps, nuts, screws and bolts, pistons and many others.
– Dry and clean lubrication
– Reduction in friction and wear
– Constant and defined frictional coefficients with very low scatter
– Use under extreme conditions such as high/low temperatures, vacuum and dust is possible
– Simplifying assembly and dismantling
– Minimising the maintenance effort
– Replacement, support or supplementing of oil or grease lubrication
– Improved running-in of machine elements
– Additional emergency running characteristics
– Suitable for almost all materials such as metals, plastics, elastomers and wood
– Very good corrosion protection
– Long shelf life
– Resistant to dirt
– Mineral oil and chemical resistant coatings possible
– Clean in application – no dirt from rubbing points and environment
– Reduction in fretting corrosion
– Very thin coatings possible
– High coverage
– In part, can be painted over
– Avoidance of stick-slip effects
– Noise reduction
Coatings compensate for unevenness in the surface and form a smooth film. As a result, the friction coefficient itself is optimised for high loads and adverse conditions. They ensure dry and clean lubrication and can make the use of greases or oils superfluous under certain circumstances. However, they can also be used in combination with these. In these cases, anti-friction coatings support the lubrication in border zones and ensure emergency running characteristics.
After the drying and hardening, the coatings form a dry film only a few micrometres thick that bonds firmly to the substrate. This film acts as friction and wear reducing separation and lubrication layer between the friction partners.
Anti-friction coatings are particularly effective in boundary and mixed friction states. Anti-friction coatings can also effectively support hydrodynamic lubrication during running-in and ensure emergency running lubrication.
Anti-friction coatings can be applied using conventional painting techniques such as spraying, dip spinning or brushing. Anti-friction coatings can also be applied using spraying drums or centrifuges and using electrostatic or automatic spraying systems or using printing or roller coating processes.