Two fundamentally different furnace types are used for MIM sintering: continuous furnaces and batch furnaces. The choice between them has a major impact on production volume, per-part cost, and material flexibility.
How each works:| Feature | Continuous Furnace | Batch Furnace |
|---|---|---|
| Loading method | Parts enter on a walking beam or pusher mechanism; exit continuously at the opposite end | Full load of parts placed in furnace at once; entire load heats, soaks, and cools together |
| Throughput | High — 5-20 kg/hour depending on furnace size | Moderate — 1-3 batches per day |
| Temperature uniformity | ±5°C across zones (larger thermal gradient front-to-back) | ±3°C across load (smaller gradient) |
| Atmosphere control | Continuous gas flow; dew point monitored at multiple points | Controlled atmosphere; can be evacuated and backfilled |
| Atmosphere options | H₂, H₂/N₂ blends | H₂, Ar, vacuum, N₂ |
| Capital cost | $500k-$1.5M (higher) | $200k-$800k (lower) |
| Per-part energy cost | Lower (efficient at steady state) | Higher (heating and cooling mass between cycles) |
| Best for | High-volume, single-material, long-running programs | Low-medium volume, multiple materials, titanium/superalloys |
- Continuous furnace: Best for automotive and consumer electronics MIM where volumes exceed 100,000 parts per year in a single material (typically 316L or 17-4PH). The continuous flow provides consistent thermal history part-to-part
- Batch furnace (vacuum): Required for titanium, Inconel, and reactive materials that need vacuum environments. Also preferred for low-volume, high-mix production where frequent material changes are needed
Continuous furnaces use a walking beam or pusher to move parts through heated zones, processing 5-20 kg/hour with consistent thermal history — best for high-volume stainless steel production. Batch furnaces heat one load at a time, offering vacuum capability for reactive materials — best for titanium, Inconel, and low-volume high-mix production. Continuous furnaces cost more but have lower per-part energy costs at high volume.