Desktop
Resin Data
PA12-GF

Poliamida 12 + Fibra de Vidrio

PA12-GF·Polyamides·Semi-crystalline

PA12-GF (PA12 + Glass Fiber) is the reinforced variant that transforms "flexible PA12" into a high-performance structural material. Same chemical base as PA12 (low moisture absorption, excellent hydrocarbon and hydrolysis resistance), but with 15–50% short glass fiber that triples stiffness, raises HDT to 160–180°C, reduces shrinkage to 0.3–0.6% and allows replacing metal in structural under-hood parts. You know it by brands like Vestamid LC-GF / L1833 (Evonik, 23–30% GF, key spec for fuel connectors), Grilamid LV-3H (EMS-Grivory PA12-GF30), Grilamid LV-5H (50% GF).

Application #1: automotive quick-connect fittings for fuel and brake lines, where the material needs rigidity to make the mechanical "click" + chemical resistance to fuel + dimensional stability to maintain the hermetic seal for 10 years of use. Here we have compiled the reference ranges from the PDS, plus the questions that come up over and over on the shop floor: when PA12-GF vs neat PA12 makes sense, vs PA66-GF, fiber length & orientation, HSHT/UV grades, and how to handle the loss of flexibility.

Share your experience in the comments — ranges vary by manufacturer and loading level, and collective discussion is what gets us out of trouble on the floor.

The ranges shown in these data tables were compiled by the MVPS team from various parameter sheets and literature, integrating the lower and upper limits for each material type.

This information must be carefully reviewed when developing injection molding processes. Final ranges and processing tolerances are the responsibility of the engineer in charge.

These ranges are not recommended for developing specific process tolerances. MVPS always recommends requesting and consulting the supplier's data sheet.

General Properties

Chemical StructureSemi-crystalline
Specific Gravity (Density)1.23:1
L/D Ratio18 – 22
Compression Ratio2 – 2.5
Tonnage Factor6.18 – 7.72kN/cm²
Thermal Diffusivity0.1355mm²/s
Max Shear Rate60,0001/s
Shrinkage0.7 – 2%
Regrind15%
Heat Deflection (HDT) @ 1.82 MPa152°C
Glass Transition (Tg) @ 10°C/min35°C
Vicat Softening @ 50N165°C

Drying

Drying Temperature71 – 82°C
Drying Time3 – 6h
Recommended Moisture0.2%
Recommended Dryer TypeDesiccant
Dew Point-40°C

Temperatures

Melt227 – 238°C
Nozzle227 – 238°C
Front227 – 238°C
Middle221 – 232°C
Rear216 – 227°C
Demolding88 – 93°C
Mold (Cooling)71 – 82°C
Feed Throat10 – 49°C

Processing

Back Pressure3.4 – 6.9bar
Screw Speed40 – 70RPM
Injection SpeedMedium – High
Barrel Occupancy20 – 70%
Injection Pressure300 – 2,000Pbar
Holding Pressure75 – 1,600Pbar
Cushion6.4 – 12.7mm

Mold

Runner Diameter3.05 – 6.1mm
Gate Diameter0.76 – 1.52mm
Gate Area0.46 – 1.82mm²
Wall Thickness0.76 – 3.81mm

Venting

Depth (Vent Depth)0.0305 – 0.0508mm
Land (Vent Land)0.762 – 1.52mm
Width (Vent / Clearance)6.1 – 12.7mm
Relief (Relief Channel)0.2032 – 0.4064mm

Frequently asked questions

PA12-GF is base PA12 (Nylon 12, polylaurolactam) with short glass fibers (length 0.2–0.5 mm post-processing) dispersed in the polymer matrix, typically at 15%, 30% or 50% by weight. Neat PA12 is flexible and has low HDT (~50°C) — adding GF transforms it into a rigid, dimensionally stable material with HDT 160–180°C. The goal of reinforcement: preserve PA12's chemical virtues (low moisture absorption, fuel resistance) while adding structural mechanical properties.
+300% rigidity (modulus 1.6 GPa → 6–7 GPa). +150% tensile strength (50 MPa → 120–130 MPa). HDT from 50°C to 165°C. Shrinkage from 1.5–2% to 0.3–0.6%. Dimensional stability with humidity significantly improved (fiber doesn't absorb water, lowers hygroscopic matrix percentage). Downsides: loses flexibility almost entirely (becomes brittle), impact reduced 60–70%, abrasion on screw and ejectors (requires hardened or bimetallic steel), surface with visible fibers if mold isn't hot.
Top: automotive quick-connect fittings for fuel and brake lines (Vestamid L1833 23% GF and LC-GF are specific for this). Pneumatic fittings (industrial and automotive) — combine rigidity for click + resistance to pneumatic oils. Structural under-hood brackets that see fuel/oil (PA66-GF degrades sooner). Fuel and oil filter housings. SCR Urea/AdBlue system components. Electrical housings with high CTI under-hood. Skis, sports bindings (Vestamid has dominated there for decades). Bicycle parts (pedal clips, frame inserts).
PA66-GF wins on: temperature (HDT 245°C vs 165°C PA12-GF), absolute rigidity, cost (~40–60% cheaper), massive availability. PA12-GF wins on: dimensional stability under humidity/cyclic temperature (PA66 absorbs ~2.5%, PA12 ~0.5%), hydrocarbon chemical resistance, service life in contact with fuels, low-temperature impact (–40°C — PA66 becomes brittle). Rule of thumb: connectors submerged in fuel/oil with critical long-term seals → PA12-GF (worth the premium). Structural under-hood housings without fluid contact → PA66-GF (worth it for cost + temperature). For EV battery thermal management, both coexist depending on specification.
Short fiber (SGF): final length 0.2–0.5 mm after injection (fiber breaks during processing). It's the standard PA12-GF30 grade — good for connectors, fittings, small parts. Long fiber (LGF): pellets with fibers 10–25 mm long, surviving the process retained at >5–10 mm. Improves impact +40%, fatigue resistance, conducts loads better through the part. Cost +20–30% vs SGF. LGF applications: pedal brackets, structural seats, front modules, where you need to replace metal without sacrificing toughness. LGF processing requires special low-shear screw and wide gates to not break the fiber.
The PDS marks 80–100°C (higher than neat PA12). Cold (60–70°C) = poorly crystallized parts + poor surface with visible fibers (glass on surface). Hot (90–110°C) = full crystallization, better achieved HDT, fibers encapsulated under polymer layer → better gloss, less surface scratching. For cosmetic connectors (especially visible automotive): min 95°C. For internal functional parts: 80–90°C is enough. Remember: PA12 crystallizes slower than PA6 — don't shorten the cycle too much.
Shrinkage 0.3–0.6% in flow direction, 0.8–1.2% perpendicular (GF reduces shrinkage where aligned but not perpendicular). That anisotropy (~3× difference) can cause warping in large flat parts. Solutions: (1) multiple balanced gates for symmetric radial flow, (2) uniform wall, (3) center gate for circular parts, (4) consider PA12 + GF + MF (mineral filler) or GF + GB (glass beads) — the combination reduces anisotropy because spheres don't orient. For cylindrical quick-connect fittings, central disc or cone gate is standard.
GF is abrasive — standard screw and barrel last much less with PA12-GF than with neat PA12 (50% less life in some cases). Solutions: (1) bimetallic screw (Xaloy 800/801 or equivalent) — doubles service life, (2) non-return valve with hardened check ring, (3) ejectors with DLC treatment or deep nitriding, (4) larger gate diameter to reduce shear (fiber breaks less), (5) mold steel: H13 hardened to 50–54 HRC minimum, better PM (Powder Metallurgy) in critical zones (gates, fine cores). For high-volume production (1M+ parts), invest in P20 or S136 hardened steel + PVD coating.
Yes, slightly stricter. PA12-GF has the same base chemistry (low hygroscopic) but untreated glass fiber can absorb surface moisture and the filler sizing (silane coupling agent) can hydrolyze. Recommended: desiccant at 80°C for 4–6 h (vs 3–6 h for neat PA12), dew point ≤–30°C, target ≤0.08% moisture. In tropical climates, always 6+ hours. PA12-GF regrind needs full re-drying every time. Once dried, keep in closed bag until use or use machine-integrated dryer.
Without protection, it's not resistant — the PA12 polymer phase yellows and becomes brittle under UV in 6–12 months outdoors, like any nylon. Glass fiber doesn't protect because it's dispersed, not on the surface. For outdoor use you need UV-stabilized grade (HALS + antioxidants) or carbon black (~2%). PA12-GF grades for fuel fittings DON'T need UV stabilization because they live inside the engine compartment without direct sun. Grades for antennas, exterior automotive mirrors, outdoor sports equipment → always UV-stabilized. Some premium grades combine UV + heat stabilization (HSHT) for under-hood use near exhaust.

Sources

Discussion (0)