What will happen if we don’t remove friction from machines?

Hint: Friction is a force that opposes the motion of objects between which it acts. In machines, there are abundant moving parts like gears, screws, handles, etc. When these parts move, a frictional force is produced that has certain characteristic effects on the machine parts. These effects are undesirable and hence, we should reduce friction in machines.

Complete answer:
Whenever there is a relative motion of two objects in contact, friction acts between them. This is directly related to the coefficient of friction between the bodies which in turn depends on the roughness of the surfaces.
Friction causes the production of heat. Over use of machines can produce considerably large amounts of heat. This will hinder the working of the machine. There might be cases of internal breakdown within the machine or some short circuits due to excessive heat.
Also, friction causes wear and tear. Subsequent slipping and gliding of two machine parts would cause severe wear and tear. The machine will get damaged. There might be cases of internal defects which are not visible from outside. This will cause the machine to stop working.
There is a huge power consumption when the machine parts are damaged. Thus, the power consumption will shoot up leading to a flow of monetary funds for the machine to work well.
Hence, we need to minimize the friction between the surfaces in contact to prevent any undesirable condition.

Note:
It might seem that friction always opposes the motion. However, it is the force which is also responsible for the controlled motion. Had friction been completely absent, we couldn’t have stopped ourselves from gliding on the ground. Also, handling machines without any friction is impossible since we will lose the control on machine parts. There will be a random motion which is yet again highly undesirable.