RIM (typical)
- Large, thick-walled parts at low molding pressure
- Lower pressure tooling with lower investment
- Longer cure cycles; parts are usually painted
Process comparison
Injection Molding vs Reaction Injection Molding (RIM): Thermoplastic vs Polyurethane
RIM mixes reacting liquids that cure in the mold at low pressure. Thermoplastic injection molding melts resin and freezes it in a steel tool on a short cycle.
Process choice
Reacting polyurethane versus melted thermoplastic
RIM suits large, thick panels at modest volume. Molding suits repeating production.
Reaction injection molding mixes two liquid components, typically polyurethane, and injects them at low pressure into a mold where they react and cure. The result is a thermoset part that cannot be remelted.
NetProto does not offer RIM. This guide compares it with thermoplastic injection molding, which is what NetProto quotes.
Side by side
How the processes differ
Part size, volume, and finishing usually decide.
Thermoplastic injection molding (NetProto)
- Short cycles for repeating production
- Molded-in color and texture without painting
- Wide resin choice, and scrap can often be reground
Routing table
Which process fits the part
Qualitative only.
| Signal | RIM tends to fit | Injection molding tends to fit |
|---|---|---|
| Size | Large panels and enclosures | Parts that fit a production press |
| Walls | Thick or varying walls | Uniform walls designed for molding |
| Volume | Low to moderate quantity | Repeating production orders |
| Finish | Painted finish expected | Molded-in color or texture |
Molding readiness
Signs a RIM part could move to injection molding
Confirm these before you quote a steel tool.
The panel fits a production press
Walls can be redesigned to be uniform
A thermoplastic grade meets the impact and heat requirement
Volume is rising enough to favor short cycles
Continue exploring
Related guides
Process first, then resin.
Compare hub
All comparison guides.
Compare hubInjection molding vs thermoforming
Sheet formed parts versus fully molded geometry.
Injection molding vs thermoformingInjection molding vs blow molding
Hollow containers versus solid molded features.
Injection molding vs blow moldingInjection molding vs urethane casting
Another polyurethane route compared with molding.
Injection molding vs urethane castingFAQ
Common questions
Is RIM the same as urethane casting?
No. Both often use polyurethane, but RIM injects reacting liquids into a closed mold under low pressure, while casting pours resin into silicone molds.
Does NetProto quote RIM parts?
No. NetProto quotes thermoplastic injection molding with hardened steel tooling only.
Next step
Quote the thermoplastic version of the part
Upload CAD for steel tool and piece price together. NetProto manufacturing is ISO 9001 certified.