Coefficient of Friction ASTM D1894

Coefficient of friction (COF) is a measure of the frictional force between two surfaces. The ASTM D1894 standard is widely used to determine the coefficient of friction of materials. The test provides information on the static and kinetic resistance of one surface being dragged across another, which can be useful in predicting how materials will perform in various applications.

Test Procedure

To conduct the test, a specimen is attached to a sled of specified weight, and the sled is pulled across a second surface at a speed of 150 mm/minute. The force required to initiate motion (static) and to maintain motion (kinetic) is measured using a force gauge or load cell.

Specimen size

The specimen is typically a 64mm (2.5 in) square, while the second surface is a 254mm x 127mm (10 x 5 in) plate.

Data

The ASTM D1894 test provides both static and kinetic coefficient of friction. The static coefficient of friction is equal to the initial force scale reading divided by the sled weight, while the kinetic coefficient of friction is equal to the average force reading obtained during uniform sliding of the surfaces divided by the sled weight. The unit of measurement is typically in grams, and the test can be conducted at different loads and speeds to simulate various applications.

Conclusion

The coefficient of friction is an essential factor in the design and selection of materials for various applications. For example, in the packaging industry, a high coefficient of friction is desired to ensure that products remain in place during transport. In contrast, a low coefficient of friction is desirable for applications such as bearings and sliding mechanisms, where low frictional resistance is necessary for efficient operation.

ASTM D1894 provides a standardized method for evaluating the coefficient of friction of materials, enabling manufacturers to select the most appropriate materials for their intended applications.