Keywordssintering defectszirconia crackingfurnace warpageshade shiftsintering troubleshootingfurnace problems
A defective sintered crown almost always traces to one of five causes. This table is your first stop before you scrap the disc.
Defect → cause → fix
| Defect | Likely cause | Fix |
|---|---|---|
| Bubbles | Fast debind | Slow ramp to 600 °C |
| Warping | Uneven support | Level the shelf, centre load |
| Dull shade | Over-temp | −20 °C, recalibrate |
| Cracks | Rapid cool | Natural cool, no open door |
| Low strength | Short hold | Extend high-temp hold 30 min |
Preventive habit
Keep one reference disc per shade sintered on a known-good program; when a batch looks off, sinter the reference — if it is fine, the issue is the batch, not the furnace.
Store reference programs on the AI Furnace Series controller.
Defect quick reference
| Defect | Cause | Fix |
|---|---|---|
| Cracks | Too-fast ramp | 5 °C/min debind |
| Warp | Uneven support | Centre the puck |
| Shade shift | Thermocouple drift | Recalibrate |
| Bubbles | Binder trapped | Longer hold |
Prevent, do not repair
Most defects trace to the program, not the disc. A logged, per-shade curve removes guesswork; when a batch fails, compare its log to a good one before touching the furnace.