Hot isostatic pressing (HIP) is a post-sintering process that applies high temperature and high isostatic pressure (typically 100-200 MPa) to a MIM part, closing residual porosity and increasing density to near 100%.
What HIP achieves for MIM parts:| MIM Material | Density Before HIP | Density After HIP | UTS Improvement | Fatigue Improvement |
|---|---|---|---|---|
| 316L | 96-98% | 99.5-99.9% | 5-10% | 20-40% |
| 17-4PH | 96-98% | 99.5-99.9% | 5-10% | 20-40% |
| Ti6Al4V | 96-98% | 99.5-99.9% | 5-10% | 25-50% (critical for implants) |
| Inconel 718 | 96-98% | 99.5-99.9% | 5-10% | 20-40% |
- Medical implants: HIP is common for orthopedic implants (bone screws, plates, spinal cages) where fatigue life is critical and the cost (typically $3-10/part) is justified by the safety requirement
- Aerospace structural parts: Any flight-critical MIM component benefits from HIP to eliminate the risk of pore-initiated fatigue failure
- Pressure-tight components: Parts that must seal against gas or liquid (valve bodies, fluid fittings) benefit from HIP eliminating interconnected porosity
- Premium applications: When the specification demands >99% density, HIP is the only way to bring standard MIM from 96-98% to that level
- Non-structural parts where 96-98% density is adequate
- Parts that will be machined after sintering (machining removes the surface layer where most porosity exists)
- Low-cost applications where the HIP cost ($3-10/part) exceeds the value of the improvement
Yes. MIM parts at 96-98% density are excellent candidates for HIP. The process closes residual porosity, bringing density to 99.5-99.9% and mechanical properties to wrought equivalence. HIP is commonly specified for medical implants, aerospace components, and pressure-tight parts — adding $3-10/part depending on size and volume.
Important: HIP must be performed on fully sintered parts only. Attempting HIP on a green or brown part would crush it.