ISO 8295:1995(E) test standard: Plastics-Film and sheeting-Determination of the coefficients of friction
Two separate, independently developed methods have been proposed and have provided documented coefficients Of friction between sheet polymers and thermoforming tool materials (mainly plugs) for the first time.
1 is used to calculate coefficients of friction from the measured force and known mass of the test sled.
2000) report coefficients of friction
for wood-based structural composites as a function of grain orientation and a contact pressure ranging from 0.
The results at different coefficients of friction
are very similar and the difference between them is less then 5 %.
Standard Test Method for Static and Kinetic Coefficients of Friction
of Plastic Film and Sheeting, Annual Book of ASTM Standards, vol.
Reported benefits include lower coefficients of friction
, improved wear resistance, easier demolding, and in many cases, lower melt viscosity, which can speed injection rate and reduce cycle time.
More sophisticated forms of the theory (5) use bulk density as a function of pressure and temperature (6) and coefficients of friction
as a function of pressure, temperature, and velocity (3).
This leaves uneven amounts of coating and different coefficients of friction
The higher coefficients of friction
of thermoplastics can be improved by the addition of solid lubricants.
Parylene's static and dynamic coefficients of friction
, which are in the range of 0.
Thermoplastics internally lubricated with silicones are said to show lower coefficients of friction
, improved wear resistance, easier demolding, and (in many cases) lower melt viscosity, which can speed injection rate and reduce cycle time.