Injection Molding
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PPO Burning and Trapped Gas
Problem Phenomenon
[Problem Phenomenon] Burning and blackening at the end ribs of PPO products, accompanied by odor
Cause Analysis
During fast injection with long runners, insufficient venting causes trapped gas to heat up by adiabatic compression and burn; PPO thermal decomposition also produces corrosive gas, aggravating the harm; during on-site troubleshooting, verify item by item according to this mechanism, and avoid blindly adjusting the machine based only on experience
Solution
Ensure sufficient mold venting to cooperate with fast injection; add venting at end ribs; reduce the final-stage injection speed for burnt parts; after adjustment, take continuous samples to verify the effect, and resume mass production only after confirming stability
Key Takeaway
PPO burning is a mismatch between fast injection and venting; venting is the premise of fast injection; after confirming effectiveness, solidify the parameters and practices into the work instruction to prevent recurrence; include this case in the defect archive as a reference for troubleshooting similar problems in the future
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