Uneven film thickness: checks before die adjustment

Identify the direction of variation and stabilise the process before making a small, documented adjustment.

Identify the variation

Thickness changes along the film length call for checks on feeding, extrusion and haul-off stability. Repeated differences around the bubble require assessment of the die, circumferential temperature and cooling distribution. Die gap is not the cause of every thickness problem.

Stabilise and measure

Confirm the measurement method and sampling positions. Check material, temperature control, cooling air and bubble condition, and record the thickness profile before adjustment. Allow the process to stabilise. Rotation or oscillation can change how a film measurement position relates to the die.

Use the correct adjustment method

Adjustment mechanisms and bolt functions vary between die designs. Trained personnel should use the procedure and operating conditions specified for the installed die. Make small changes, allow the response to settle and measure again. Do not apply bolt numbering or turning directions from a missing or unrelated drawing.

Recognise a maintenance issue

If repeated adjustments do not improve the result, investigate temperature control, contamination or damage with the service team. Cleaning and repairs require the prescribed stopping, pressure release and energy isolation procedures; do not force adjusters or dismantle a pressurised die.

Keep a repeatable troubleshooting record

Use a consistent sampling method and record the resin batch, film width, measurement positions and machine operating state. Change one factor at a time and measure again after the process stabilises. Repeating variation around the bubble calls for an informed check of temperature, cooling and die condition. Do not copy temperature or die-gap settings from a different model. See the multilayer blown film range or send your machine and film details for a compatibility discussion.