# How to Calculate the Coefficient of Friction

It’s important to understand and know how coefficients of frictions are calculated when rigging and moving loads.  The COF is a value that corresponds to the relationship between two objects and how this relationship affects the ability to move across the applicable surfaces.  Normal coefficient of frictions fall between the value of 0 and 1.  Below is a table outlining some of the more common COF used in rigging and moving loads. The above calculations can be used to solve what force will be needed to move an object across a surface that is either flat, uphill, or downhill.  Please refer to the included legend for calculating purposes.  These calculations are important to ensure the right force is being calculated when moving an object.  Below is a simple example of how this is done.

If we are moving a 10,000# load of material with a steel base plate (steel) across a concrete floor (concrete) the force needed would be:

COF X Weight of the load = Force

By looking at the table we can see the COF for steel on concrete is 0.6

0.6 x 10,000 = 6000 lbs of force required to move the load

In the same scenario, if we were moving the same load across steel plating instead of concrete, the force needed would be:

By looking at the table we can see the COF for steel on steel is 0.10

0.10 x 10,000 = 1000 lbs of force required to move the load

The force would be lower because the COF of steel on steel is much lower than steel on concrete.

To take it a step further, if you were to place the same load on machine skates (load on wheels), the force needed would be:

By looking at the table, we can see the COF for a load on wheels is 0.05

0.05 x 10,000 = 500 lbs of force required to move the load

As you can see, when putting a load on wheels is an option, the force required to move a load can be greatly reduced, allowing for additional options for handling the move.