Prevention Checklist For Polyethylene Film Lines
To prevent problems in extruding polyethylene blown film, purchase the proper equipment to do the job.
Checklists are excellent memory joggers for both maintenance and production personnel. An operator should check each film line with a checklist at least one time per shift. Lines should also be checked when there is an order change, and at start-up or at shutdown, since some equipments can be inspected only at those times.
All or part of the following checklist usually is incorporated in plant process Descriptions. The checklist cannot include everything because each polyethylene blown film extrusion shop is different. And regular use of the checklist should minimize many potential problems.
Row Materials (Resin, Additives and Regrind)
- Are the polyethylene resins and additives the right grades for the film being extruded?
- Are the quantities of raw materials sufficient to complete the run?
- Are the resin loading system filters clean ?
- Were the additive feeders emptied and cleaned when out of service to prevent dribble from contaminating the next resin to be run.
- Were the recycle/regrind systems for salvaging edge trim and roll scrap recently checked to make sure that the proportion of scrap to virgin resin is accurate?
- Are the scrap rolls of poly ethylene film compatible with the virgin pelletized resin being used?
- Are all rolls of scrap clean and labeled by resin type?
- Was the equipment cleaned between resin changes to prevent contamination?
- Are all hoppers and boxes of polyethylene resins covered, not only to prevent contamination of the resins, but also to prevent possible damage to the extruder by tramp metal or other Materials?
Extruder Drives of Polyethylene film lines
- Most extruders are equipped with some type of variable speed drive for consistent output control.
Are all fluctuations in revolutions per minute or power consumption, as indicated by
the screw drive ammeter or tachometer, checked along with other causes for extruder surging?
- Are all dirty air filters replaced? Otherwise, sensitive solid-state drive components can overheat and burn out.
- Are the extruder transmissions and thrust bearings properly lubricated?