After debinding, the MIM part transitions from a "green" part (full binder content) to a "brown" part (mostly metal powder, residual binder 5-10%). The amount of binder removed is tracked by measuring weight loss.
What it measures: The percentage of the total binder that was removed during the debinding step. It is NOT the total weight lost — it is specifically the fraction of the binder that was successfully removed. The calculation:Weight loss % = (Wgreen - Wbrown) / (Wgreen × Binder wt%)
Where:
- Wgreen = weight of the molded green part
- Wbrown = weight after debinding
- Binder wt% = weight fraction of binder in the feedstock
Weight loss = (15.00 - 14.20) / (15.00 × 0.06) = 0.80 / 0.90 = 88.9%
This means 88.9% of the binder was removed. Given the target of 90-95%, this part needs a slightly longer debinding cycle.
Weight loss targets by binder system:| Binder System | Target Weight Loss | Consequence of Under-Debinding | Consequence of Over-Debinding |
|---|---|---|---|
| POM (catalytic) | 90-95% | Carbon contamination, black lines in sintered part | Brown part too fragile, handling damage |
| Wax-polymer (solvent) | 85-92% | Carbon contamination, reduced ductility | Part may collapse during handling |
| Water-soluble (PEG) | 90-95% | Carbon residue, surface defects | Excessive handling fragility |
It is the percentage of the binder that has been removed during the debinding step. The target is 90-95% binder removal for most MIM processes. Weight loss below 90% risks carbon contamination during sintering (the residual binder carbonizes, causing black lines and reduced corrosion resistance). Weight loss above 95% indicates potential over-debinding, leaving the brown part too fragile for handling.