Thermoforming (typical)
- Lower tool investment with a single-sided tool
- Large, shallow parts such as trays, panels, and covers
- Wall thins at deep draws and corners; trimming step after forming
Process comparison
Injection Molding vs Thermoforming: Sheet Parts vs Fully Molded Geometry
Thermoforming stretches heated sheet over a one-sided tool. Injection molding fills a closed steel tool, so both sides and every feature are defined.
Process choice
Sheet formed shells versus fully molded parts
Thermoforming suits large, shallow shells. Molding suits detailed parts that repeat.
Thermoforming heats a plastic sheet and pulls it over a single-sided tool with vacuum or pressure, then trims the part from the sheet. Only one side of the part is controlled by the tool.
NetProto does not offer thermoforming. This guide helps teams decide when a part has outgrown sheet forming and should be quoted as an injection molded part.
Side by side
How the processes differ
Tool investment and part detail usually decide.
Injection molding (NetProto)
- Closed steel tool defines both sides of the part
- Ribs, bosses, snap fits, and holes molded in one shot
- Repeatable walls and cosmetics across production orders
Routing table
When thermoforming should give way to molding
Qualitative only. Upload CAD for molding economics.
| Signal | Thermoforming can suffice | Quote molding |
|---|---|---|
| Geometry | Open shell with one cosmetic side | Features on both sides, bosses, or snaps |
| Volume | Low or seasonal quantity | Repeating production orders |
| Wall control | Some thinning is acceptable | Consistent walls for strength or fit |
| Assembly | Parts added to the shell later | Features consolidated into one part |
Molding readiness
Conversion checklist
Confirm these before you quote a steel tool.
The shell fits a molding press rather than a sheet forming line
Resin chosen from the materials library
Features that were fastened to the shell are listed for consolidation
Annual volume supports a steel tool investment
Continue exploring
Related guides
Process first, then resin.
Compare hub
All comparison guides.
Compare hubInjection molding vs blow molding
Hollow containers versus solid molded features.
Injection molding vs blow moldingInjection molding vs rotational molding
Large hollow parts versus detailed production parts.
Injection molding vs rotational moldingPackaging
Molded packaging components and closures.
PackagingFAQ
Common questions
Can a thermoformed part be converted to injection molding?
Often, but the part usually needs redesign. Molding needs draft, uniform walls, and gate locations that a sheet part never had. DFM review flags them.
Does NetProto quote thermoforming?
No. NetProto quotes injection molding with hardened steel tooling only.
Next step
Quote molding when the shell needs real features
Upload CAD for steel tool and piece price together. NetProto manufacturing is ISO 9001 certified.