The Coefficient of Friction is evaluated by ASTM D1894 test method. Initial and moving friction, or resistance to movement, is calculated when one material is dragged across another material. Static and kinetic coefficients of friction are reported as a result.
Coefficient of Friction (COF) ASTM D1894 is a standard testing method designed to measure the initial and moving friction, or resistance, of one material being dragged across another material. Initial friction is also known as static or starting friction, and moving friction is also known as kinetic friction.
The material specimen is attached to a sled of defined weight. This sled is pulled across another surface at a speed of 150 mm/minute. The force required to start the sled is measured to get the static friction. In addition, the force required to maintain the motion of the sled, that is, kinetic friction is measured.
Square specimens of 64 mm (2.5 inches) are used with a second surface with a fixed dimension of 254 mm × 127 mm (10 × 5 inches).
The static and kinetic coefficient of friction is calculated and reported. The static coefficient of friction is computed by dividing the initial force scale reading by the weight (in grams) of the sled used. Furthermore, the average force reading, obtained during uniform sliding of the surfaces, divided by the sled weight (in grams) gives the kinetic coefficient of friction.