Plastic film · Laboratory data reduction
Plastic Film Coefficient of Friction Calculator
Calculate static and kinetic coefficient of friction from plastic-film sled mass, initial peak force, and average sliding force.
Formula and method
Normal force (N) = sled mass (kg) × 9.80665 m/s². Static COF = initial peak force ÷ normal force. Kinetic COF = average sliding force ÷ normal force.
Inputs and units
Enter the total moving sled mass and the force channel values for initial peak and defined sliding average. Document both contacting surfaces, test direction, conditioning, contact time, travel speed, travel interval, apparatus geometry, and whether the interface is film-to-film or film-to-another surface.
Worked example
A 200 g sled with 0.588399 N initial peak and 0.392266 N sliding average gives 0.3 static COF and 0.200 kinetic COF.
When to use it
Use to reduce a recorded film friction trace for incoming-film checks, converting or packaging trials, and same-method lot or treatment comparisons.
How to interpret the result
COF is dimensionless. Static and kinetic values answer different handling questions; retain both. A result is meaningful only with the complete surface pairing and test condition.
Assumptions and limitations
The calculation does not remove stick-slip, misalignment, curling, contamination, blocking, electrostatic, speed, dwell, or conditioning effects. Local gravity convention and apparatus friction may be handled differently by a lab procedure.
Validation guidance
Check sled mass, load-cell zero and calibration, level and alignment, specimen orientation, surface identity, and the averaging interval. Run the required replicates and inspect the force trace rather than retaining only one number.
FAQ
Does lower COF always mean better packaging performance?
No. The desired range depends on feeding, winding, stacking, sealing, printing, product retention, and the specific contacting surfaces.