A MIM part passes through three distinct physical states during production. Each state has different dimensions, strength, handling requirements, and inspection criteria.
The three states compared:| Property | Green Part | Brown Part | Sintered Part |
|---|---|---|---|
| When it exists | After injection molding | After debinding | After sintering |
| Dimensions (% of final) | 118-122% (oversized) | 117-121% (slightly shrunk from green) | 100% (final dimensions) |
| Strength (flexural) | 15-25 MPa | 3-8 MPa (fragile) | 500-1300 MPa UTS |
| Binder content | 100% (full binder system) | 5-10% residual | 0% — binder completely removed |
| Color | Dark — color of the binder | Lighter, more porous appearance | Metal color — matte silver/grey for stainless |
| Handling | Manual or automated, moderate care | Must be handled carefully — fragile | Full production handling, no restrictions |
| Inspection | Weight, visual (short shots, cracks, flash) | Visual (cracks), weight loss verification | Full dimensional + material testing |
- Green part: Approximately 18-22% larger in each linear dimension than the final sintered part. Green parts are strong enough for automated handling and can be stored before debinding
- Brown part: The most fragile state — about the strength of chalk. Must be placed on the sintering tray after debinding and not moved again until after sintering. Any handling between debinding and sintering risks cracking
- Sintered part: The final product. Full strength, final dimensions, ready for inspection and any secondary operations. Approximately 14-20% smaller than the original green part
Green parts are molded and still contain the full binder — they are 18-22% oversized and have moderate handling strength. Brown parts have had most binder removed — they are extremely fragile (chalk-like) and must be handled with extreme care. Sintered parts are the final product — full density, final dimensions, and full mechanical properties. The shrinkage from green to sintered is typically 14-20% linearly.