Poor Film Feeding in Bag Making Machine – Causes & Solutions
Poor film feeding is usually shown as film deviation, slipping, wrinkling or jamming. It is mainly caused by three factors: unstable tension control, mechanical wear, and static electricity. Below are the detailed causes and solutions.
1. Unbalanced Tension Control
This is the main cause of poor feeding. Either too high or too low tension will result in unstable film transport.
• Causes:
Improper unwinding tension setting, making film too tight (leading to breakage) or too loose (leading to accumulation).
• Solutions:
◦ Adjust tension: Reset unwinding tension based on film material and thickness. Generally, thicker film requires higher tension.
◦ Check brake: Inspect the brake pad on the unwinding shaft for wear or over‑tightness to ensure stable resistance.
2. Worn or Dirty Mechanical Parts
Problems at physical contact points directly block film advance.
• Causes:
◦ Worn rubber roller: Severe wear reduces friction and causes slipping.
◦ Dirty guide rollers: Plastic scraps or dust on the surface increase friction.
◦ Seized bearings: Worn or poorly lubricated bearings cause rough rotation.
• Solutions:
◦ Clean rollers: Wipe all guide rollers and rubber rollers thoroughly with alcohol or cleaner.
◦ Replace rubber roller: Replace if the surface is smooth and glossy due to wear.
◦ Lubricate bearings: Regularly lubricate guide roller bearings for smooth rotation.
3. Static Adsorption
Static electricity generated during high-speed operation causes film to stick on machine parts and increases feeding resistance.
• Causes:
Static electricity from film friction makes film adhere to guide rollers or frame.
• Solutions:
◦ Install static eliminator: Add a static eliminating bar (ion bar) near the unwinding frame.
◦ Increase humidity: Use a humidifier to keep workshop humidity at about 50%–60% to reduce static.
4. Poor Film Quality
Defects in raw material can also cause feeding problems.
• Causes:
Uneven film thickness, poorly wound rolls, or burrs on film edges.
• Solutions:
Check film quality and replace with qualified raw material.
Operation Suggestion
Before adjusting the machine, manually rotate the unwinding shaft to check whether resistance is even. This helps quickly locate the problem.
