Powder Metallurgy & Precision Tooling

Metal Injection Molding (MIM/CIM) Shrinkage Calculator

Calculate feedstock powder solids volume loading ($\Phi$), volumetric/linear sintering shrinkage ($S_L$), isotropic mold enlargement scaling factors ($F$), and CNC mold cavity dimensions for surgical, aerospace, and firearm MIM components.

1. Input Parameters

Feedstock Solids Volume Loading (Φ %):

Volume fraction of metal/ceramic powder in organic polymer binder (typical: 58% - 66%).

Sintered Theoretical Density (ρ_rel %):

Final relative density achieved after high-temperature vacuum sintering.

Nominal Finished Part Dimension (D_final in mm):

Target blueprint drawing dimension after sintering and thermal cooldown.

Binder Polymer Mass Fraction (B %):

Thermal/catalytic debinding weight loss percentage from green to brown part.

2. Calculation Results

Linear Shrinkage (S_L)

14.12 %

Tooling Scale Factor (F)

1.1644 ×

Mold Cavity Dimension

52.40 mm

Volumetric Shrinkage (S_V)

36.35 %

3. Geometric Visualizer

Tooling & Vector Prepress Engineering Notes

Metal Injection Molding (MIM/CIM) Sintering Physics: MIM mixes micro-fine spherical metal/ceramic powder (0.5–20 µm) with a thermoplastic binder system. During thermal or catalytic debinding, the binder is extracted; during high-vacuum sintering, capillary pore elimination causes massive isotropic shrinkage:

S_V = 1 - [Φ / (ρ_rel / 100)]
S_L = 1 - (1 - S_V)^(1/3) = 1 - [Φ / (ρ_rel / 100)]^(1/3)
Tooling Factor F = 1 / (1 - S_L) = [(ρ_rel / 100) / Φ]^(1/3)

CAD/CAM Tooling Rules: Scale the finished part DXF model from its center of mass using exact factor $F$. Sinker EDM electrodes and CNC mold cavities must incorporate 0.5°–1.5° draft angles and oversized gate runner radii to prevent green-part tearing during ejection.