Blow Molding
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Excessively Thin Wall Thickness at the Parting Line of High-Density Polyethylene Blow Molded Products
Problem Phenomenon
The wall thickness of the blow molded product near the mold parting line is significantly thin, with low strength and easy to crack from there.
The thin wall at the parting line affects the sealing and pressure resistance of the product.
Cause Analysis
（1）The parison is excessively squeezed at the parting line
（2）The blow-up ratio is too large, and the inflation at the parting line is the most severe
（3）The venting at the mold parting line is poor, and the melt does not adhere tightly
（4）The parison position is offset and is not at the center of the mold
（5）The blowing air pressure is too large, and the parting line is excessively stretched
Solution
（1）Adjust the parison wall thickness distribution, appropriately thickening near the parting line
（2）Optimize the blow-up ratio to avoid being too large
（3）Set vent grooves or vent holes at the mold parting line
（4）Adjust the parison position to ensure it is at the exact center of the mold
（5）Appropriately reduce the blowing air pressure and use staged blowing
Key Takeaway
The thin wall at the parting line is caused by parison squeezing or uneven inflation, and the parison wall thickness distribution and blowing process need to be optimized.
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