When you ask for an injection mold quote, one of the biggest choices is what the mold is made of. It affects the price, how fast you get parts, and how many parts the mold can make before it wears out.
The short version
| Aluminum (rapid / soft tooling) | Pre-hardened steel (P20, 718H) | Hardened steel (H13, S136, NAK80) | |
|---|---|---|---|
| Cost | Lowest | Medium | Highest |
| Speed to first parts | Fastest | Medium | Slowest |
| Typical life (shots) | Thousands to tens of thousands | Hundreds of thousands | Up to a million or more |
| Best for | First runs, market tests, bridge tooling | Most startup products | High volume, abrasive or clear/glossy parts |
(Life depends on the part, plastic and care. Treat these as rough ranges and confirm with your mold maker.)
Aluminum molds ("rapid tooling")
Aluminum is soft and machines quickly, so the mold is cheaper and faster to make. The trade-offs:
- It wears out sooner, especially with glass-filled plastics.
- It's harder to make very fine, glossy surfaces.
- Some complex features are harder to build.
It's great when you want a first production run (say a few thousand units) to test the market before investing in a long-life steel mold. This is often called bridge tooling, because it bridges prototyping and full production.
Steel molds
Pre-hardened steels like P20 and 718H are the common choice for startup volumes: durable, reasonably priced, and easy to modify.
Hardened steels like H13 or S136 are for very high volumes, glass-filled plastics (which wear molds quickly), and parts that need a mirror polish (clear lenses, glossy surfaces).
Soft tooling isn't only aluminum
Some shops call pre-hardened steel "soft tooling" too, compared with fully hardened steel. Always ask which steel grade and how many shots the mold is rated for, in writing.
How to choose
- Not sure if the product will sell? Aluminum or P20 for the first run.
- Confident of tens of thousands per year? P20/718H steel.
- Hundreds of thousands, glass-filled or optical parts? Hardened steel.
- Design might still change? Cheaper tooling hurts less if you have to redo it. Better still, keep prototyping.
Next steps
- How much does injection molding cost?
- How to get an injection mold made in China
- Find mold makers in Dongguan and Shenzhen
Updated 29 September 2026
