Glass filled resin
- Higher stiffness and heat deflection
- Anisotropic shrink can warp if gate and rib layout ignore fiber orientation
- Glass rich surfaces on show faces unless texture hides them
Material comparison
Glass Filled vs Unfilled Resins: Stiffness, Warp, and Tooling
Glass fill raises modulus and heat but can show glass rich surfaces and anisotropic warp. Unfilled grades look better and flow easier in thin walls.
Material comparison
Fill is a structural decision, not a default upgrade
Add glass when testing proves unfilled resin cannot hold tolerance or temperature.
Glass filled nylon and PBT are common when brackets must stay stiff above 100 C service.
Unfilled grades stay on cosmetic covers and snaps that need uniform shrink and better surface.
Resin choice
Glass versus Unfilled at a glance
Use this routing before you lock the BOM. NetProto molds both once the resin is specified on the quote.
Unfilled resin
- Better surface for cosmetics and paint
- More uniform shrink in thin walls
- Lower stiffness and heat capability
Decision table
Where each resin usually wins
Qualitative tradeoffs for molded parts. Confirm shrink, fill, and tooling details on the material guide.
| Factor | Glass filled resin | Unfilled resin |
|---|---|---|
| Stiffness | Much higher with 30 percent glass typical | Baseline modulus |
| Warp | Directional, needs DFM | Often easier to balance |
| Surface | Can show glass | Smoother A surfaces |
| Tool wear | Abrasive, plan maintenance | Standard maintenance |
Before you quote
Send this context with your CAD
The instant quote uses your material choice for fill, gate, and steel assumptions.
Structural load or heat requirement
Cosmetic class on visible faces
Tolerance direction relative to gate
Existing validation on a filled grade
Material guides
Full property pages
These library pages carry datasheets, DFM notes, and quote checklists.
Glass filled nylon
Open the Glass filled nylon molding guide.
Glass filled nylonNylon
Open the Nylon molding guide.
NylonContinue exploring
Related comparisons
Open a sibling guide or jump to the full material library.
Compare hub
All comparison guides.
Compare hubMaterials library
Deep guides per resin family.
Materials libraryNylon 6 vs 66
Pick nylon type before fill level.
Nylon 6 vs 66ABS vs PC
Unfilled commodity versus engineering clear.
ABS vs PCFAQ
Common questions
Does fill always reduce shrink?
Fill changes shrink magnitude and direction. Steel must be tuned to the filled grade, not an unfilled guess.
Next step
Quote both options with the same CAD
Upload once, switch resin in the quote flow, and compare piece price on the same tool. NetProto manufacturing is ISO 9001 certified.