Process selection
Injection Molding vs 3D Printing
Injection molding wins on unit cost at volume; 3D printing wins on speed to first part and design freedom with no tooling. The crossover point is where per-part savings repay the mold.
| Injection Molding | 3D Printing | |
|---|---|---|
| Tooling | Steel or aluminum mold required | None |
| First part lead time | 3 to 8 weeks | Hours to days |
| Per-part cost at 10,000 units | 0.10 to 2 USD | 5 to 50 USD |
| Per-part cost at 10 units | Very high (tool amortized) | Low |
| Geometry freedom | Draft, uniform walls needed | Near unlimited, internal channels |
| Break-even volume | Above roughly 500 to 5,000 parts | Below that range |
| Material range | Broad, production-grade resins | Growing, some production polymers |
Choose Injection Molding when
- You are producing thousands or more of the same part
- You need the lowest possible unit cost
- The part uses a standard production resin
Choose 3D Printing when
- You need parts in days, not weeks
- Volumes are low or the design is still changing
- Geometry is too complex to mold, or you want no tooling risk
The verdict
Use 3D printing for prototypes, low volumes, and complex one-offs, and switch to injection molding once volume is high enough that per-part savings pay back the mold, often a few hundred to a few thousand parts.
Cost comparison
The cost math is a straight line versus a curve: printing costs roughly the same per part at any volume, while molding starts with a 10,000 to 100,000 USD tool and then drops to cents per part. Quote both at your real annual volume, including regrind, scrap, and printer depreciation. If the design will change within a year, weigh the cost of retooling against printing's zero-tooling flexibility.
Common questions
At what volume is injection molding cheaper than 3D printing?
It varies with part size and material, but the crossover is commonly a few hundred to a few thousand parts. Below that, printing avoids tooling cost; above it, molding wins on unit price.