The direct cause is low strap tension or a brake system failure. The strap cannot hold its position after tightening. Check four areas: tension adjustment, brake system, strap material, and mechanical structure.
Tension adjustment
A tired tension spring loses force after long use. It cannot hold enough tension on the strap. A loose adjustment knob lets the tension mechanism shift, so the preset tension no longer works. A scale position error means the tension reading does not match the actual output.
Brake system faults
Friction plate wear is a common cause. Replace the brake plate when its thickness is below 2 mm, based on the 2024 Cologne Packaging Machinery Technical Manual. Oil or grease on the friction surface lowers braking force. An electromagnetic brake can also fail when coil resistance falls outside the standard range, usually 15 to 20 Ω.
Strap material issues
Polypropylene with stretch recovery over 12% can pull back after tensioning. Poor tooth forming also hurts grip. A tooth angle deviation over 5° affects how well the teeth hold. Width tolerance matters too. A width error over ±0.3 mm leaves too much clearance between the strap and the guide rail.
Mechanical structure issues
Guide rail wear causes strap slip. A flatness error over 0.1 mm/m is enough to create movement. A roller bearing with radial clearance over 0.02 mm affects feed stability. In the tooth pressing mechanism, replace the pressing block when wear depth exceeds 1/3 of the original size.
Operation note
Cut power before inspection. Wear protective gloves when adjusting the tension mechanism. The mechanism can move suddenly and cause pinching.
When a tension spring, brake plate, guide rail, or pressing block reaches its wear limit, Hansheng Automation can machine a replacement from customer drawings. We match material, tolerance, and surface treatment to the working conditions.
Hansheng Automation also machines custom precision parts for other equipment, including filling machinery, tobacco packaging machinery, yacht components, and RC car components. We work from customer drawings for single pieces and small batches.
