Clamp jaws accumulate softened polymer, masking adhesive, oil, dust, oxidation, and fragments from damaged sheet edges. The contamination changes friction and contact height, causing local slip, pressure points, or edge marks.
The jaw pattern should be inspected after cleaning and compared with the defect location. A polished deposit can be difficult to see but may transfer a repeatable mark or reduce grip when hot. Opposing jaw surfaces should contact evenly without sharp embedded particles.
Cleaning methods must not round intentional grip features or leave solvent residue. Worn teeth, pads, or coatings should be repaired rather than repeatedly roughened. Jaw condition should be included in preventive maintenance because recipe changes cannot stabilize an unpredictable friction surface.