When solids come into contact with each other, between two contact surfaces creates a sticky bond there. The reduction of friction by creating a thin film of a liquid or gaseous body so as not to give rise to that bond is called Lubricant.

The substance used for that purpose is called Lubricant.

There are solid and liquid lubricants.

Solid-state lubrication is a lubrication method that creates a solid powder layer between friction surfaces in contact with each other. According to Cu Long’s law of friction, there exists molybdenum disulfide powder and graphite.

Liquid lubrication is lubrication by forming a liquid film of 10-5 mm or more on the friction surface and obeying Newton’s law of viscous friction.

Coulomb’s law of friction means that the friction force F is only proportional to the vertical load P independent of the sliding speed and contact area.

Friction force F = μP

Newton’s law of viscous friction is friction in lubricants.

It is proportional to friction velocity u and friction area A and inversely proportional to liquid film thickness h0.

Friction force F = (ηuA / h0) κ

Requirements for lubrication purposes:

Anti-friction function: Reduces friction, wear and heat generation
Cooling function: Prevents temperature rise in the lubricating part
Sealing function: Tightness of cylinder and piston
Corrosion prevention function: Prevent rust and corrosion
Dustproof function: Prevent foreign impurities
Clean function: clean … remove foreign impurities, maintain cleanliness
Stress dispersion function: The dispersion of the load is concentrated on the gear, bearing

In order to achieve the above objectives, the following three factors must be considered:

Operating conditions such as load, temperature, rotation speed, etc. on friction surfaces (bearings, gears, slides, etc.)
Lubricant type and performance
Lubrication method and lubrication conditions

Lubrication can be achieved when these three elements are well combined.

Provide the right lubricant at the right amount, at the right time, effectively and reliably at the point where lubrication is required