Glass-filled nylon is polyamide compounded with glass, either as small glass beads or as short glass fibers. In powder-bed fusion, the common grade is PA12 filled with roughly 30–40% glass beads, often designated PA12 GB; it is processed by SLS and is also available for MJF. For FDM, filaments such as PA6-GF and PA12-GF contain short glass fibers, typically about 15–30% by weight. The suffixes GB and GF follow the ISO 1043 abbreviation system for fillers and reinforcements.
Both forms raise stiffness, heat deflection temperature and dimensional stability, and glass beads in particular reduce warping on long, flat powder-bed parts. The trade-offs are higher density, lower elongation and impact strength, and abrasive behavior in machining. Glass is electrically insulating and, unlike carbon fiber, largely transparent to radio signals, which suits housings for electronics and antennas. Glass-filled grades are offered through Uretyco's partner network; because they are specialty materials, grade, process and lead time are confirmed during quote and order review.
Mechanical and physical properties
| Property | Typical value | Notes |
|---|---|---|
| Filler content | ≈ 30–40% glass beads (powder bed); ≈ 15–30% glass fiber (FDM) | By weight. The number in a designation such as PA6-GF30 gives the glass content in percent. |
| Tensile strength | ≈ 30–50 MPa (powder bed); ≈ 50–90 MPa (FDM, XY, dry) | Glass beads add stiffness, not strength. Fiber-filled filament is stronger along the printed beads and much weaker across layers. |
| Tensile modulus | ≈ 2.5–3.5 GPa (powder bed); ≈ 3–7 GPa (FDM, XY, dry) | Unfilled PA12 reaches ≈ 1.7 GPa. PA6-based parts lose stiffness as they absorb moisture. |
| Elongation at break | ≈ 5–10% (powder bed); ≈ 2–6% (FDM) | Far below unfilled PA12 (≈ 15–24%): parts crack rather than bend. |
| Density | ≈ 1.2–1.4 g/cm³ | Roughly 20–40% heavier than unfilled PA12 and heavier than carbon-filled nylon. |
| Heat deflection temperature (HDT) | ≈ 95–115 °C at 1.8 MPa (powder bed) | ≈ 155–175 °C at 0.45 MPa. FDM grades based on PA6-GF can reach higher values; check the datasheet. |
| Max. continuous service temperature | ≈ 80–110 °C | Set by the nylon matrix; the glass keeps parts stiffer toward the upper end. Check creep data for loaded parts. |
| Moisture uptake | Low (PA12); moderate to high (PA6) | PA6-based filament and parts absorb far more water than PA12, which lowers stiffness and causes slight swelling. Filament must be dried before printing. |
| Warping and shrinkage | Low | Glass reduces shrinkage; glass-bead powder-bed parts stay flatter than unfilled PA12. |
| Anisotropy | Low (glass beads); high (FDM fiber) | Spherical beads stiffen all directions alike; fibers align with the printed beads, and FDM parts are weakest across layers. |
Typical ranges from published data for glass-bead PA12 powders and glass-fiber PA6 and PA12 filaments, measured on printed test bars. Values differ between powders, filaments, machines and build orientations, and PA6-based grades change with humidity. For load-bearing parts, use the datasheet of the grade named in your quote and validate printed samples, ideally in the conditioned state.
Glass-filled PA12 on SLS and MJF
Glass-bead PA12 is processed like standard PA12: unfused powder supports the part, so no support structures are needed and complex geometry is possible. SLS parts are off-white, MJF parts gray. The rules from Uretyco's MJF and SLS design guide apply, with a few additions:
- Walls: at least 0.8 mm for cosmetic features and 1.5 mm for functional walls. Thin walls that would flex in PA12 tend to crack in glass-filled grades, so add stiffness with ribs rather than thin, springy sections.
- Flat and long parts: the glass reduces warping, which makes glass-bead PA12 a good choice for panels, covers and long housings that must stay flat.
- Clips and hinges: elongation is low, so avoid high-strain snap-fits and living hinges; use PA11 or PA12 for those features.
- Holes and threads: holes from 0.5 mm; for threads, print bores of at least 1.5 mm and tap after printing, or use heat-set inserts. Glass wears taps faster than unfilled nylon.
- Hollows and fits: escape holes of at least 4 mm (6–8 mm above 50 cm³ of internal volume); 0.4 mm clearance for sliding fits and at least 0.5 mm between parts printed together.
Glass-fiber-filled powders also exist for SLS and reach higher stiffness in the build plane, but they are less common and more direction-dependent. Their availability is confirmed during quote review.
Glass-fiber nylon on FDM
FDM uses PA6 or PA12 filament filled with short glass fibers. It produces strong, stiff parts and suits large, simple geometry, but it is one of the more demanding FDM materials:
- Drying and enclosure: nylon filament absorbs moisture within hours. It must be dried and is usually printed in an enclosed printer to limit warping and layer cracking.
- Abrasion: glass fiber wears brass nozzles quickly, so hardened or other wear-resistant nozzles are used, typically 0.4 mm or larger.
- Orientation: the fibers align with the printed beads, and parts are weakest across layers. Put the main load path in the layer plane and state it in the order notes if orientation matters.
- Conditioning: PA6-GF parts absorb moisture in service, becoming tougher but less stiff and growing slightly. Design with conditioned properties, or choose PA12-GF where stable dimensions in humid air matter.
- Large flat areas: the fibers reduce warping, but long, flat parts still benefit from ribs and generous corner radii.
- Threads and inserts: heat-set inserts hold well in nylon; leave enough wall around each insert.
Tolerances and surface
For powder-bed parts, plan for ±0.3 mm or ±0.3% per linear feature, the values Uretyco's MJF and SLS guide gives; glass-bead grades usually hold flatness better than unfilled PA12. FDM parts follow the default of ±0.5 mm or ±0.5% (whichever is greater) and vary with orientation, part size, supports and post-processing, and PA6-based parts change size slightly as they take up moisture. Locating bores, datum faces and bearing seats that need better accuracy can be machined after printing; mark them on a drawing. Final values are confirmed in the quote and order review.
Finishing options
Powder-bed parts take the same finishes as PA12, while FDM parts are usually used as printed or painted. Glass near the surface makes parts feel slightly harder and more abrasive than unfilled nylon.
| Finish | Effect | Notes for glass-filled nylon |
|---|---|---|
| Standard depowdered or as-printed | Lowest cost | Powder bed: grainy, off-white (SLS) or gray (MJF). FDM: matte with visible layer lines. |
| Bead blast | Uniform matte surface | The usual cosmetic baseline for powder-bed parts; typically +5–10% for PA12. |
| Dyeing | Even dark color | Common for gray MJF parts; confirm availability and color for glass-filled grades. |
| Vapor smoothing | Sealed, smoother surface | Listed for powder-bed nylon; confirm availability and effect on glass-filled grades in the quote. |
| Primer and paint | Color-critical surfaces | Possible on both routes; mask mating faces and threads. |
Choose glass beads when you need stiffness, heat resistance and flatness in all directions, especially on complex powder-bed parts. Choose glass fibers when a part needs higher strength and stiffness along a known load path and FDM geometry is acceptable. If the load direction is unknown, beads are the safer choice.
Cost and lead-time drivers
Glass-filled grades are specialty materials and are usually less expensive than carbon-filled ones; the process sets most of the price:
- Powder bed: priced by powder volume and build height, like PA12. Hollowing thick volumes reduces cost, and build packing affects when parts ship.
- Material availability: glass-filled powders and filaments are not stocked by every partner, and special materials can add lead time; availability is confirmed during quote review.
- FDM: drying, enclosed printing and wear-resistant nozzles add preparation; print time follows part volume, walls and infill.
- Post-machining: reamed bores, tapped holes and inserts add operations, and glass wears tools faster than unfilled nylon.
- Documents: inspection reports and material documentation are opt-in and can extend the lead time. Request them at quote time.
Glass-filled nylon vs. common alternatives
| Material | Stiffness | Elongation at break | Density | Best for | Processes on Uretyco |
|---|---|---|---|---|---|
| Glass-bead PA12 | ≈ 2.5–3.5 GPa | ≈ 5–10% | ≈ 1.2–1.3 g/cm³ | Stiff, flat, heat-tolerant housings and fixtures | SLS, MJF |
| Glass-fiber PA6 or PA12 | ≈ 3–7 GPa (XY, dry) | ≈ 2–6% | ≈ 1.2–1.4 g/cm³ | Strong brackets and fixtures with a known load path | FDM |
| PA12 | ≈ 1.6–1.8 GPa | ≈ 15–24% | ≈ 0.93–1.01 g/cm³ | Tough general-purpose parts | MJF, SLS |
| CF-PA12 | ≈ 3.5–9 GPa (XY) | ≈ 3–6% | ≈ 1.0–1.1 g/cm³ | The stiffest and lightest powder-bed parts | MJF, SLS |
| PA11 | Similar to PA12 | ≈ 45% | ≈ 1.05 g/cm³ | Impact, snap-fits, living hinges | SLS, MJF |
Carbon-filled nylon is stiffer and lighter, but carbon fiber can interfere with radio signals and usually costs more. Glass-filled nylon is the better fit for insulating, RF-transparent housings and for parts that must stay flat. Unfilled PA12 or PA11 remains the choice where parts must flex or survive impact.
When not to choose glass-filled nylon
High-strain snap-fits, living hinges and impact-loaded parts: use PA11 or PA12. Lowest weight for a given stiffness: CF-PA12 is lighter and stiffer. Tolerances tighter than about ±0.3 mm without post-machining. Sliding contact against soft mating parts: exposed glass can abrade them. Smooth cosmetic surfaces straight from the machine. PA6-based parts whose dimensions must stay stable in changing humidity: choose a PA12-based grade.
Typical applications
- Housings and covers near motors, lamps or other warm components.
- Enclosures for electronics, sensors and antennas that need an insulating, RF-transparent material.
- Jigs, fixtures and assembly aids that must stay stiff and flat.
- Brackets, mounts and fan shrouds.
- Ducts and covers in automotive and machinery prototypes.
- Large, stiff FDM parts such as frames and mounting plates.
Specifying glass-filled nylon on Uretyco
- 1Upload STL, 3MF or STEP
Add a short note on the intended use, the load case and the operating temperature.
- 2Choose the route and filler
Glass-bead PA12 on SLS or MJF for complex, stiff and flat parts; glass-fiber filament on FDM for strength along a known load path. Leave the choice open if either is acceptable.
- 3State the stiffest direction and environment
Note humidity, chemicals and whether orientation is critical, so the right base polymer and build orientation are chosen.
- 4Choose the finish
Standard, bead blast, dyed or painted; confirm smoothing options for glass-filled grades in the quote.
- 5Add a drawing for critical features
Mark bores to be reamed or machined, tapped holes, inserts and inspection requirements; grade and lead time are confirmed during order review.
FAQ
What is the difference between glass beads and glass fibers?
Glass beads are small spheres that stiffen the nylon evenly in all directions and reduce warping, but add little strength. Short glass fibers add more strength and stiffness, mainly along the direction in which they are aligned, so parts become direction-dependent. Powder-bed grades usually use beads, FDM filaments usually fibers.
Glass-filled or carbon-filled nylon?
Carbon-filled nylon is stiffer and lighter. Glass-filled nylon is usually less expensive, electrically insulating and largely transparent to radio signals, and glass-bead grades behave more evenly in all directions. Decide by the dominant requirement: weight and stiffness favor carbon; insulation, RF transparency and flatness favor glass.
SLS, MJF or FDM?
SLS and MJF suit complex geometry, internal features and small series, with no supports and consistent properties in all directions. FDM suits larger, simpler parts and strength along a defined direction. If more than one route is acceptable, say so and let the quote compare cost and lead time.
Do glass-filled nylon parts change with humidity?
PA12-based grades absorb little water and stay dimensionally stable. Parts printed from PA6-based filament absorb considerably more, which reduces stiffness and causes slight swelling after printing. For parts in humid environments or with tight fits, prefer PA12-based grades or design with conditioned properties.
Related resources
- PA12 (Nylon 12)Tougher, unfilled powder-bed nylon.
- CF-PA12 (Carbon-Fiber Nylon)Stiffer, lighter powder-bed composite.
- PA11 (Nylon 11)For impact, snap-fits and hinges.
- Designing for MJF and SLSWalls, escape holes, fits and finishes.
- 3D PrintingChoosing between FDM, SLA, SLS and MJF.
- Technical Drawings and TolerancesWhat belongs on the 2D drawing.
Related materials
Composites
CF-PLA
PLA filled with chopped carbon fiber: stiffer, lower-warp and with a fine matte finish, but more brittle than plain PLA and still limited to about 50–55 °C. For stiff jigs, fixtures and premium-looking indoor parts.
Composites
PETG-CF
PETG filled with chopped carbon fiber: stiffer and more dimensionally stable than PETG, tougher and more heat-resistant than CF-PLA. For functional fixtures, brackets and housings that see mild heat, moisture or chemicals up to about 65–70 °C.
Plastics
PA12 Nylon
The workhorse powder-bed polymer: strong, tough, low-moisture nylon printed by MJF or SLS without supports. For functional prototypes, housings, ducts and low-volume end-use parts.
Plastics
PA11 Nylon
Bio-based nylon from castor oil for powder-bed fusion. More ductile and impact-resistant than PA12 at similar strength, which makes it the choice for snap-fits, clips, hinges and parts that must survive drops.
Composites
CF-PA12
Carbon-fiber-filled PA12 for MJF and SLS: several times stiffer than unfilled nylon at almost the same weight, for jigs, fixtures, brackets and end-of-arm tooling. Stiffer but less tough, and direction-dependent.
Plastics
PLA
Bio-based thermoplastic and the easiest FDM material to print: stiff, accurate and low-warp, but brittle and soft above about 50–55 °C. The default for visual prototypes, fit checks and indoor fixtures that never get warm.
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