Date：2025-07-25 Views：1002
Yes, MIM can exhibit porosity defects similar to casting, though their formation mechanisms differ.
However, these defects are preventable through targeted measures.
Process | Porosity Type | Cause |
Casting | Gas Porosity | Entrapped gas failing to escape before metal solidification. |
MIM | Kirkendall Porosity (in the feedstock preparation) | Diffusion imbalance in alloying elements (e.g., Ni agglomerates) due to inhomogeneous powder-binder mixing. |
Gas Entrapment (in the injection molding process) | Air trapped during injection, related to poor venting, gate design, injection speed, or abrupt wall-thickness transitions. |
Kirkendall Porosity Mitigation
Increase mixing time & shear rate for homogeneous feedstock.
Monitor mixer power: stable power = optimal mixing.
Use capillary rheometers for batch uniformity control.
Gas Entrapment Mitigation
Parameter Adjustment | Action |
Injection Pressure | ↑ Hold pressure |
Injection Speed | ↓ Speed to allow air escape |
Mold Temperature | ↑ Temperature to reduce viscosity |
Gate Design | • Enlarge gates |
Venting | Add vents at weld lines/air traps |
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