Molds & Tooling
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PC Gas Trapping and Burning
Problem Phenomenon
Black spots and scorch marks appear at the end of the PC product cavity, possibly accompanied by a burnt smell, at fixed positions.
Cause Analysis
When venting is poor, compressed air adiabatically heats up and burns the plastic; PC's high processing temperature makes the diesel effect more likely to occur; high-speed filling at the end and blocked vent slots both induce it.
Solution
①Open/clean vent slots; ②Reduce injection speed at the end; ③Do not over-apply clamping force to avoid closing the vents; ④Check insert fitting clearances; ⑤Reduce release agent contamination of the vents.
Key Takeaway
PC 'high-temperature material fears gas trapping more': venting is a life-saving design; the higher the processing temperature, the greater the risk of gas-trapping burning, and the design and maintenance of the venting system must be in place; after confirming effectiveness, solidify the parameters and practices into the work instruction to prevent recurrence.
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