Why do we need lubricants?

The basic nature of mechanical machines is that they consist of moving parts. Those moving parts come in contact with each other in motions of either sliding or rotating. 

However, there will be resistance to these moving surfaces. This resistance is known as friction. Friction is the resistance to motion of a surface moving relative to another.

Even the smoothest and the most polished surface will have friction. Forcing that movement against friction will lead to the breakaway of the surfaces, which is what we know as wear. Continuous wear will result in the machine to lose its function and eventually fail. 

Wear is not the only undesirable effect of friction in machines. Friction also generates heat. It can be a good thing if we want to heat up ourselves (like rubbing our hands), but in a machine, it leads to an overheating problem. Overheating can temporarily melt contacting surfaces and weld them together causing seizure.

Another unwanted effect of friction is energy losses. The higher the friction, the more energy is needed to slide surfaces relative to each other. To prevent wear, excessive heat, and energy losses, friction must be minimized. Using a lubricant is the solution.

A lubricant is what separates the two contacting surfaces via a thin layer of oil. Now friction between the surfaces is significantly reduced, making movement easy. In other words, lubricant helps machine parts easily move against each other by forming a layer of oil in between their contact region.

Despite having a lubricant, wear can still occur due to factors such as load, speed, and temperature will affect the thickness of the oil layer. This is known as lubrication type, which is a topic to be covered in the next newsletter.

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