Thermoforming
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Shear Overheating Blistering Caused by Too Low LCP Barrel Temperature
Problem Phenomenon
【Problem Phenomenon】When the barrel set temperature is too low and plasticization relies on high screw speed, fine bubbles appear inside or on the surface of the product, which are amplified after soldering
Cause Analysis
When the barrel temperature is too low, the melt achieves fluidity by shear heating; excessive shear breaks molecular chains and produces local overheating and degradation, and gas is entrained into the melt; Vectra literature clearly states that low barrel temperature + high speed is a typical cause of blistering
Solution
Raise the barrel set temperature to the range recommended by the resin supplier, reduce screw speed and back pressure, and replace shear heating with external heating; confirm that the actual melt temperature does not exceed the upper limit
Key Takeaway
Low temperature and high shear are hidden causes of LCP blistering; external heating should be primary and shear secondary; after confirming effectiveness, solidify the parameters and practices into the work instruction to prevent recurrence
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