Engineers rarely have only one way to make a part. The question is which route gives the required part at the lowest total cost over the programme life. Here is the framework we use when a customer asks whether powder metallurgy is worth considering.
Start With Volume
This is the single biggest factor. Powder metallurgy requires a compaction die, so there is a tooling investment that must be recovered. As a rough guide:
- Under 1,000 pieces per year: machining is usually cheaper
- 1,000-10,000 pieces per year: grey zone – compare both
- Above 10,000 pieces per year: powder metallurgy usually wins on cost
Then Look at Geometry
PM shines when the part is complex in the pressing direction and simple across it. Count the machining operations on your current drawing: every broached keyway, every turned spline, every drilled cross-hole is a cost that a PM die can often form for free.
Compare the Real Numbers
| Factor | Powder metallurgy | Machining | Casting + machining |
|---|---|---|---|
| Tooling cost | Medium-high | Low | Medium-high |
| Unit cost at volume | Low | High | Medium |
| Material waste | 3-10% | 40-60% | 15-30% |
| Tolerances | ±0.3% as-sintered, ±0.05% sized | ±0.01 mm achievable | ±1% as-cast |
| Typical density | 6.4-7.4 g/cm³ | Full density | Full density |
| Lead time to first samples | 4-7 weeks | 1-2 weeks | 6-10 weeks |
Do Not Forget the Hidden Costs
- Scrap and rework. PM’s consistency reduces both.
- Assembly. PM can integrate two machined parts into one sintered part.
- Inventory. Fast, repeatable PM cycles allow leaner batch sizes.
- Surface treatment. Steam treatment and impregnation can replace a plating step.
A Hybrid Route Is Often the Answer
The best design is often mostly PM with a small amount of machining. Let the die form 95% of the geometry, then machine only the two faces that truly need it. This hybrid approach frequently delivers 80% of the cost saving with none of the risk.
How We Help
Send us your current machined part and its annual volume. We will return a free manufacturability review that states, in plain numbers, whether PM would save money – and if not, we will say so.
