Process selection
Thermoforming vs Injection Molding
Thermoforming heats a plastic sheet and forms it over a tool with low tooling cost; injection molding fills a closed tool for detailed, dimensionally precise parts. Tooling economy and part size versus detail and precision.
| Thermoforming | Injection Molding | |
|---|---|---|
| Starting material | Plastic sheet | Plastic pellets |
| Tooling cost | Low, 500 to 20,000 USD | High, 10,000 to 100,000+ USD |
| Part detail | Limited, one formed side | High, fine features both sides |
| Wall thickness control | Varies across the part | Precise and uniform |
| Part size | Large parts feasible | Small to medium typical |
| Break-even volume | Hundreds to low thousands | Thousands and up |
| Cycle time | Seconds to minutes | Seconds |
Choose Thermoforming when
- Large, shallow parts like trays, panels, and packaging
- Low to medium volumes with a tight tooling budget
- Simple geometry with detail on one side
Choose Injection Molding when
- Small, detailed parts with tight tolerances
- High volumes that amortize the mold
- Uniform walls and fine features on both faces
The verdict
Thermoform large, simpler parts at low tooling cost and moderate volume; injection mold small, detailed, high-tolerance parts at volumes that justify the mold.
Cost comparison
Thermoform tooling in cast aluminum at 2,000 to 20,000 USD is often a tenth of an equivalent injection mold, but sheet stock costs more per kilogram than pellets and trimming adds a step. For a large tray at 5,000 units a year, thermoforming usually wins; for a small detailed housing at 50,000 units, injection molding's lower material and cycle cost repays the mold.
Common questions
Is thermoforming cheaper than injection molding?
Thermoforming has much lower tooling cost, so it is cheaper at low to medium volumes and for large parts. Injection molding wins on per-part cost at high volume and gives far more detail.