A.Possible causes of uneven film thickness

• Uneven or unstable die opening discharge. Check if the die opening gap is aligned.
• Die head temperature is different from molten material temperature.
• Uneven or unstable die head temperature.The heating of the head should be evenly distributed to ensure the equal flow of resin at the mold mouth. Otherwise, the high temperature part of the film stretches and expands to become thin; and vice versa to become thick.
• The cooling air ring is incorrectly positioned. Check for alignment.
• Uneven air supply from the cooling air ring. Ensure that the cooling air ring delivers air evenly.
• Blow bag ratio is too large.
• Air flow in the plant is too fast.In the cooling line of the blown film pipe under the part, do not allow external wind fluctuations caused by airflow interference, available plastic film curtain.
• The pinch rollers are not level or are not centered with the die head. The blown film machine and upper pinch rollers need to be aligned with the die head.
• How to solve the uneven thickness caused by the deviation of the die opening gap.

B.How to solve the uneven thickness caused by the deviation of the die opening gap.

The structure of blown film machine mold consists of two types, one is up-blowing and the other is down-blowing. If it is up-blowing, you have to adjust the die cover, and if it is down-blowing, you have to adjust the die sleeve.

• Adjustment through the principle of the mold, if the gap between the mold mouth is small, the film just out of the mold mouth is thinner, the thin film cools quickly, thus difficult to stretch, difficult to stretch the film eventually forming the film is thicker, thus the screw should be adjusted tight.
• Adjust by observing the membrane bubble. When the membrane bubble bulge, it means that the membrane is thinner, this time the screw needs to be adjusted loosely.