MIM vs PM Density: Why MIM Parts Are Stronger

Engineers often ask: what is the actual difference between MIM and conventional PM (powder metallurgy)? The single most important answer is density.

Density comparison by process:

Material	MIM Density	PM Density	Why MIM is Denser
316L stainless	96-98%	85-90%	Finer powder + binder-assisted packing + higher sintering temperature
Fe-2Ni low alloy	95-97%	85-90%	Same — finer PSD and binder system enable denser green state
17-4PH	96-98%	87-91%	MIM achieves near-full density; PM is inherently porous

What 8-10% more density means for part properties:

Property	MIM (97% density)	PM (88% density)	Impact
UTS (316L)	500-550 MPa	250-350 MPa	MIM is 50-80% stronger
Elongation (316L)	40-55%	8-15%	MIM is 3-5x more ductile
Corrosion resistance	Near-wrought	Poor (porosity traps corrosive media)	MIM passes salt spray; PM does not
Pressure tightness	Seals at >95% density	Leaks through interconnected pores	MIM can hold pressure; PM cannot
Surface finish Ra	1.6-3.2 µm	3.2-6.3 µm	MIM is smoother — 50% less surface roughness
Fatigue strength	200-260 MPa	80-120 MPa	MIM is 2-3x better in cyclic loading

The key takeaway: PM is cheaper for simple shapes (coarse powder + press-and-sinter = low cost), but the parts are inherently porous. MIM costs more per part but delivers properties closer to solid metal. The choice is not "which is better" — it is "does your application need the density?" Quick Q: What is the difference between MIM and PM density?

MIM achieves 95-99% of theoretical density, while conventional PM achieves 85-92%. This 8-10% difference translates into MIM being 50-80% stronger, 3-5x more ductile, and capable of holding pressure and resisting corrosion — all of which PM cannot reliably do. The trade-off is cost: PM is 50-70% cheaper for simple shapes at high volume.