A material’s coefficient of friction is the ratio of the force acting between the material surfaces to the pulling force. Measurements are usually made material surface against itself, with a lower friction coefficient indicating a lower resistance.
Friction has two components; dynamic and static:
- Dynamic friction (or kinetic friction) is the force needed to maintain motion between two surfaces.
- Static friction is the force needed to create movement between two surfaces.
The coefficient of friction is a critical property of all materials which run on high speed manufacturing lines; particularly those in the printing and packaging industry. Coefficient of friction is routinely specified for plastic flowrapping films.
Slip coefficient = 1/coefficient of friction
A high coefficient of static friction is often desirable for sacks which need to resist sliding when stacked.
Standards and Accreditation
Smithers Pira use an RDM horizontal plane instrument to measure both static and dynamic coefficients of friction in accordance with British and International standard BS EN ISO 8295 and ASTM D1894 for plastic films and sheeting.
Smithers Pira is UKAS, ISO 17025 accredited to both BS EN ISO 8295 and ASTM D1894.