Material Drying
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PEEK Silver Streaks Misdiagnosed as a Drying Problem
Problem Phenomenon
Silver streaks still appear on PEEK products after drying verification is qualified; adding drying time and temperature brings no improvement, and the silver streak positions are relatively fixed in the area ahead of the gate.
Cause Analysis
When the nozzle tip is partially blocked or has a cold slug area, the melt passes with obstruction and generates abnormal shear, forming streaks similar to moisture silver streaks; PEEK residing for several hours above 380℃ forms carbon deposits on the inner wall of the nozzle.
Solution
①First quickly measure moisture to rule out drying factors; ②Disassemble and inspect the nozzle tip to remove carbon deposits and blockages; ③Check the nozzle heater band and thermocouple to eliminate cold spots; ④The machine must be purged when shut down for more than 15 minutes.
Key Takeaway
PEEK silver streaks are the defect with the highest clinical misdiagnosis rate; when moisture is qualified, immediately turn to nozzle inspection; nozzle carbon deposits form in just a few hours, and regular disassembly inspection is necessary maintenance for high-temperature materials.
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