Silver Streaks / Splay
Causes, Solutions & Prevention in Injection Molding
Silver streaks are caused by steam moisture air or degraded material stretched along the flow path.
Below you will find general information about this defect. To get a pinpoint solution tailored to your specific machine, material, and process parameters using the world’s most comprehensive injection molding troubleshooting database — sign up and access AI-powered troubleshooting, 7 engineering calculators, and detailed project tracking.
🔍Symptoms & Visual Identification
⚠️Root Causes by Category
⚙️ Process
- Material not dried moisture turns to steam at gate U-shaped marks
- Screw retraction too long air enters melt spray pattern
- Back pressure too low
- Barrel zone 1 too cold poor feed
🔲 Mold
- Nozzle contact surface gap air drawn in
- No cold slug well degraded tip enters cavity
- Contamination on mold surface
🧪 Material
- Undried material most common cause
- MB carrier resin mismatch streaks after color change
- Degraded regrind particles
📋 General
- Dryer motor direction reversed after maintenance no actual drying
- Dryer filter clogged
✅Solutions & Corrective Actions
⚙️ Process
- Dry material per TDS check dryer motor direction first
- Reduce screw retraction distance
- Increase back pressure
- Check nozzle contact for gaps
🔲 Mold
- Add cold slug well
- Clean mold surface
- Ensure full contact at nozzle sprue interface
📋 General
- Check dryer filter clean if needed
- Allow cold-stored material 24h at ambient before use
- Purge barrel thoroughly after color change
🛠Step-by-Step Troubleshooting
Check Process Parameters
Dry material per TDS check dryer motor direction first
Inspect the Mold
Add cold slug well
Verify Material Condition
Undried material most common cause
❓Frequently Asked Questions
What causes silver streaks / splay in injection molding?
Silver Streaks / Splay is caused by several factors including: Material not dried moisture turns to steam at gate U-shaped marks; Screw retraction too long air enters melt spray pattern; Nozzle contact surface gap air drawn in; No cold slug well degraded tip enters cavity; Undried material most common cause; MB carrier resin mismatch streaks after color change.
How do you fix silver streaks / splay in injection molding?
Start by checking key parameters: Drying time (h), Drying temperature (°C), Back pressure, Nozzle temperature. Dry material per TDS check dryer motor direction first
Which plastics are most affected by silver streaks / splay?
Common materials include: ABS, PA6, PC, PET, PBT. Pay special attention to drying, shrinkage and mold temperature for each grade.
How do I prevent silver streaks / splay in future production runs?
Prevention relies on three pillars: (1) process optimisation — verify Drying time (h), Drying temperature (°C); (2) mold maintenance — check gates, vents and cooling channels; (3) material control — ensure correct drying and virgin/regrind ratio.
What is the difference between silver streaks / splay and similar defects?
Silvery streaks or brush marks radiating from gate. U-shaped marks mean moisture. Spray pattern means air entrainment. This distinguishes it from related surface defects during visual inspection.
📐Related Calculators
Run these engineering calculators to verify your process parameters and prevent this defect.
🔗Related Defects
About MBPlastiPro
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