What properties does a mechanical chain lubricant need to have?

A chain's service life depends mainly on its lubrication system. In fact, a study has shown that 60% of chain defects can be attributed to insufficient or inadequate lubrication. Lubrication flaws are behind many different forms of wear (adhesive wear, abrasive wear, wear caused by small amounts of play between surfaces, corrosive wear, etc.). Wear on an axle / socket can lead to the chain being lengthened, while wear on the roller will affect the play between the socket and the roller.

Throughout the drivetrain’s service life, the lubricant used has several roles to play:
– it forms a film between surfaces that rub together (axle/sockets, sockets/rollers and rollers/teeth), as well as between internal plates and external plates, rollers and the teeth. This is so as to prevent (as far as possible) metal parts coming into direct contact with other metal parts, irrespective of operating conditions (load, temperature, etc.);
– it ensures that the lubricant film remains elastic so as to cushion the meshing jolts between axles and sockets and between sockets and rollers, as well as reducing noise;
– it has to be present in sufficient quantities in the drivetrain's moving parts and it has to have appropriate physical-chemical properties to be able to remain in these articulations (Extreme-Pressure);
– it has to protect the drivetrain against stresses from the ambient environment. In particular, it has to protect it against oxidation and corrosion;
– it has to evacuate heat energy generated by friction for high-speed transmissions in particular.

If all of these conditions are met, the lubricant can help reduce the friction coefficient and so save energy. This reduces wear on the drivetrain and so helps ensure that the transmission system operates properly.