Static vs. Kinetic COF: Why is Your Film Slipping on the VFFS Machine?
In the high-speed world of Vertical Form Fill Seal (VFFS) packaging, the difference between a perfect production run and a morning of wasted film often comes down to a single invisible variable: the Coefficient of Friction (COF) . Whether your film is stuttering over the forming collar or slipping through the pull belts, understanding the interplay between static and kinetic friction is the key to maintaining machine uptime. Section 1: Static vs. Kinetic COF in Packaging To troubleshoot machine failures, we must first distinguish between the two phases of friction. Static COF (The Starting Force): This is the peak force required to initiate movement between two resting surfaces. In VFFS, this occurs when a heavy film roll begins to unwind after a pause, or when the film rests against the metal forming collar before the pull cycle begins. Kinetic COF (The Sliding Force): Also known as dynamic friction, this is the continuous force required to maintain movement at a steady, constant sp...