Sr. No.	Problem / Trouble	Probable Cause/s	Remedy
1.	Bubble breaks frequently	- Charge point opening is obstructed by clogged polymer granules - Polymer is not melting well	- Remove hopper & remove clogged material block - Increase temperature and/or increase number of screws.
2.	Thickness variation in transverse direction	- Die-gap not properly adjusted - Air ring is dirty	- Adjust the die gap. - Clean the air ring.
3.	Blocking	- High extrusion temperature which produces high film temp. and cause blocking - High tension wind-up causing pressure on film roll. Higher the film temp. at wind-up, the greater this effect. High pressure on the film at nip-rolls causing internal blocking film at nip-rolls causing internal blocking - Excessive electronic treatment of the film - Unfavorable environmental conditions during extrusion or storage can also cause blocking. High room temperatures, on the other hand, may cause film shrinkage. Both extremes in temp. cause film blocking. - Thin gauge film are more susceptible to blocking because of higher built-up of static charge. Also thinner films run at higher line speed and higher tension which increases tendency to blocking. - Film characteristics which effect blocking are film smoothness & density. Higher density films have harder surfaces and consequently less tendency to block.	- Lower the film temp. by :- Reducing the temperature. Reducing air ring temperature. - Increasing distance between die and nip rolls. Reduce the tension by slightly decreasing the contact roller speed. Reduce the pressure at the nip rolls by adj. the air pressure on pneumatic cylinder. - Check the level of treatment & adjust it. - Take proper precautionary measures. - Adjust various processing parameters to achieve results. - Use proper material band.
4.	Wrinkles	- The frost line is too high causing poor gauge control around circumference of the tube and uneven gauge in film. Die ring out of adj. causing gauge variation which again results in an uneven pull at the nip rolls - Film too cold when it reaches the nip rolls and therefore its stiffness may cause crimping at the nip and wrinkling. - The pressure across the face of the rolls may not be uniform either because the rolls are not parallel or slightly eccentric. - Guide roll not properly aligned with the nip rolls. - Webbing of the bubble due to air currents - Winders shaft may be pulling the film at an uneven tension or too high a tension	- Adjust the frost line by :- Extruder speed. Line speed. Blowing more cooling air against the bubble. Adjusting die opening - Increase the film temperature at nip rolls by lowering height of the nip rolls or raising the melt temperature or increasing the screw speed and the nip rolls speed or extrusion rate. - Restore parallelism by fitting rear nip roll with small pneumatic cylinder to provide uniform pressure. Recondition the rubber rollers to maintain proper resiliency. - Adjust. - Protect bubble from air current drafts then certain. - Support the tube with horizontal guide bars at 2 or 3 location. Use a spreader or a expander roll for removing such wrinkles.
5.	Poor transparency	- Low blowup ratio - Poor homogenisation of material - Low frost line	- Try a blow-up ratio between 2 and 3. - Select a screw of proper design. Use a dense screen pack. - Raise the frost line.
6.	Die lines	- Hang up inside die or at die lips - Plugged breaker plate - Scratches on die lips	- Clean die. - Purge at high temperature. Replace screen pack. - Polish lips.

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