The debinding cycle must be optimized for the specific part geometry — especially wall thickness. A cycle that works for a 2 mm wall may not adequately debind a 6 mm section.
Catalytic debinding (POM binder) — parameter guidelines by wall thickness:| Wall Thickness | Temperature | HNO₃ Concentration | Time | Weight Loss Target |
|---|---|---|---|---|
| < 2 mm | 110-120°C | 0.5-1.0% | 3-5 hours | 90-95% |
| 2-5 mm | 120-130°C | 1.0-1.5% | 5-8 hours | 90-95% |
| 5-8 mm | 130-140°C | 1.5-2.0% | 8-12 hours | 88-93% |
| 8-12 mm | 135-140°C | 2.0% | 12-18 hours | 85-92% (may need longer) |
| > 12 mm | Not recommended | — | — | Center cannot be debound |
- Weigh green part (after molding)
- Calculate expected binder weight = green weight × binder wt%
- Weigh brown part (after debinding)
- Calculate weight loss % = (green - brown) / (green × binder wt%)
- Target: 90-95% for standard parts; 85-90% acceptable for thick sections
| Symptom | Likely Cause | Fix |
|---|---|---|
| Weight loss < 85% | Cycle too short or temperature too low | Increase time by 25% or raise temperature 5°C |
| Weight loss > 95% (thin sections) | Cycle too long, or temperature too high | Reduce time — risk of brown part damage |
| Black lines on sintered surface | Residual binder carbonized | Increase debinding time; check weight loss target |
| Surface discoloration (brown part) | Condensation of binder on part surface | Increase gas flow rate; check furnace exhaust |
Set debinding temperature based on wall thickness: 110-120°C for thin walls (<2 mm), up to 135-140°C for thick sections (8-12 mm). Verify by weight loss — target 90-95% binder removal. If weight loss is below 85%, the center of the part may still contain unremoved binder that will carbonize during sintering, causing black lines and reduced corrosion resistance.