Surface Energy Shift and Gloss Drift under Friction Sled Cycles
Friction sled cycles strip migratory slip agents, elevating polar surface energy while generating micro-roughness that causes severe specular gloss drift.
Friction Sled Testing
Resistance Measurement
Physical testing methods quantify static and kinetic coefficients of friction for paperboard and plastic film packaging materials. Standardized apparatuses pull a weighted sled across a flat material substrate at a constant speed while measuring required horizontal drag force. Friction sled testing yields empirical values that dictate how packaging substrates feed through automated handling machinery and high speed printers.
Static friction values represent the force required to initiate sliding motion, whereas kinetic friction measures ongoing resistance during continuous movement. Substrate surface roughness, moisture content, and chemical slip additives directly alter measured frictional forces.
Motion Profile
Laboratory procedure involves mounting a specimen to a horizontal test bed while a secondary specimen covers the contact surface of the weighted sled. Digital load cells record the initial force peak alongside average force readings across a specified sliding distance. Performing friction sled testing according to standards like TAPPI T 549 or ISO 8295 ensures comparable results across paper mills and converting facilities.
Environmental humidity fluctuations alter cellulose moisture content, causing significant deviations in surface resistance and sled displacement behavior. Surface dusting or loose fibre lint create unpredictable friction spikes during testing.
Converting Interface
Uncontrolled friction levels lead to web breaks or multi-sheet feeding jams on high speed packaging lines. Low friction values cause stack instability during pallet transport and storage. Friction sled testing defines operational windows for substrate surface slip performance.