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Type of Defect: |
Silver Streak (1/2) |
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Description: |
White (or silver) streak running on the surface of the substrate along the flow of material |
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Observation Method: |
Visible by the human eye / silvery long streaks, sometimes U-shaped |
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Recommendation Upon Observation: |
Better visibility under polarized light |
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Other Evaluation Method: |
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Cause |
Countermeasure |
| Air inclusions in the melted material |
Adjust back pressure (too low) |
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Air inclusions in the melted material |
Adjust screw rotation (too fast) |
| Air inclusions in the melted material |
Check leakage between nozzle and sprue bushing |
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Excessive moisture in the material |
Adjust drying condition (usuallly temperature is too low, or time span is too short) |
| Excessive moisture in the material |
Avoid exposing material to drastic temperature changes prior to molding |
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Excessive moisture in the material |
Check dryer perfomance |
| Excessive moisture in the material |
Check leakage with pre-dryed material conveying system |
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Suck back being too far back |
Adjust suck back, too far back |
