What are the factors which affect the coefficient of static friction?

Answer 1

1. Dry surfaces

2. For low surface pressures the friction is directly proportional to the pressure between the surfaces. As the pressure rises the friction factor rises slightly. At very high pressure the friction factor then quickly increases to seizing
3. For low surface pressures the coefficient of friction is independent of surface area.
4. At low velocities the friction is independent of the relative surface velocity. At higher velocities the coefficent of friction decreases.

1. Well lubricated surfaces

2. The friction resistance is almost independent of the specific pressure between the surfaces.
3. At low pressures the friction varies directly as the relative surface speed
4. At high pressures the friction is high at low velocities falling as the velocity increases to a minimum at about 0,6m/s. The friction then rises in proportion the velocity 2.
5. The friction is not so dependent of the surface materials
6. The friction is related to the temperature which affects the viscosity of the lubricant