Injection Molding vs CNC vs 3D Printing: Cost Crossover Points
For plastic parts: 3D printing wins below 50 units, CNC machining is competitive 50–500 units, and injection molding becomes cheapest above 500–1,000 units depending on tooling cost. For metal: CNC wins up to 5,000 units; investment casting or MIM only beats CNC at very high volumes.
The right manufacturing process depends entirely on volume. Knowing the crossover points prevents over-spending on tooling for low volume or over-paying per part at high volume.
Plastic Parts: Where the Crossovers Sit
- **1–50 parts**: 3D printing (MJF or SLS) is cheapest. No tooling, fastest turnaround. - **50–500 parts**: CNC machining of plastic stock is often competitive, with better mechanical properties than printed parts. - **500–5,000 parts**: Aluminum prototype tooling + injection molding amortizes; per-part cost drops to €0.50–€2. - **5,000+ parts**: Steel production tooling pays back; per-part cost €0.10–€1.
Metal Parts: Different Math
For metal, CNC machining stays competitive far longer because metal injection molding (MIM) and investment casting both require expensive tooling and have geometric limits. For volumes under 5,000 units, CNC is almost always the right answer.
Cost per Plastic Part by Volume (typical)
| Volume | MJF | CNC | Injection Molding |
|---|---|---|---|
| 1 | €25 | €80 | N/A (tooling) |
| 10 | €18 | €55 | N/A (tooling) |
| 100 | €12 | €35 | €40 (with €4k tool amortized) |
| 1,000 | €10 | €30 | €6 (with €5k tool) |
| 10,000 | €10 | €28 | €1.20 (with €8k tool) |
Frequently asked questions
- When does injection molding tooling pay off?
- Typically at 500–1,000 parts for simple geometries with €3k–€5k aluminum tooling. Complex parts with steel tooling (€10k+) need 5,000+ parts to break even.
- Can I bridge prototype-to-production with one process?
- Yes. Many customers use MJF for 1–500 parts, then move to injection molding for 1,000+. CNC bridges the middle for tight-tolerance functional parts.
- How much does an injection mold cost?
- Aluminum prototype mold: €2,500–€8,000 (10,000–50,000 shots). Steel production mold: €8,000–€40,000 (1M+ shots).