Overview
PA12 is the long-chain nylon — 11 methylene units between amide groups versus PA6’s 5 — and that simple structural change drives most of its behavior. More carbon, less amide means dramatically less moisture absorption, lower density, better low-temperature toughness, and better chemical resistance, at the cost of lower stiffness and lower maximum service temperature.
The defining PA12 fact: moisture absorption is ~1.5% at saturation, compared with ~9.5% for PA6 and ~8.5% for PA66. That single property ratio changes the design conversation completely:
- PA12 parts don’t grow significantly in service (~0.1% vs 0.5–0.8% for PA6)
- PA12 parts don’t lose 50% of their strength in humid air
- PA12 stock shapes can be machined and shipped without moisture-conditioning logistics
- PA12 filament can be FDM-printed without the bubbling and weakness that wet PA66 filament suffers from
The trade is less stiffness and strength — PA12 modulus is 1.5 GPa vs PA66’s 3.0 GPa dry (and 1.5 GPa conditioned — note that PA12 in its as-shipped state has similar stiffness to moisture-conditioned PA66). For load-bearing parts that will see humid service, PA12 delivers similar real-world performance to PA66 conditioned, with no surprises.
When to pick PA12 over PA66
| Driver | Pick PA12 if… | Pick PA66 if… |
|---|---|---|
| Moisture stability | Critical (tight tolerances, dimensional reuse) | Acceptable to design conditioned |
| Impact toughness | Drop testing, sports goods, structural | Standard wear/gear loads |
| Max temperature | <\10°C continuous | 100–110°C continuous |
| Stiffness | Acceptable to design thicker | Need maximum stiffness |
| Cost | Justifies premium | Cost-sensitive bulk |
| FDM/SLS printing | Yes — PA12 is the default | Specialty FDM grades only |
| Medical device | USP Class VI required | Generally not medical-grade |
| Fuel/oil/brake fluid | Continuous flexible service | Static fittings |
Machining notes
PA12 machines well but is softer and more rubbery-feeling than PA66. Practical recipe:
- Sharp carbide or HSS, positive rake
- Speed: 300–600 SFM (lower than PA66 due to heat sensitivity)
- Feed: 0.005–0.012 in/rev
- Coolant: recommended for heavy cuts
The two PA12-specific machining concerns are different from PA6/PA66:
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Cutting heat matters more. PA12’s max service temperature is ~90°C, well below PA66’s 110°C. Heavy cuts that generate substantial local heat can scorch or locally soften the surface. Use sharp tooling, moderate feeds, and flood coolant on roughing.
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No moisture-conditioning compensation needed. The big advantage of PA12 over PA66 in shop terms — what you machine is what the customer gets. No 0.3–0.5% growth allowance for in-service moisture pickup. Tight-tolerance work is dramatically easier than with PA66.
PA12 stock is also less common than PA66 stock, so machinist familiarity is lower. Allow a learning curve for shops new to the material — feeds and speeds that work for PA66 will be slightly too aggressive for PA12.
Variant selection guidance
- Extruded PA12 (TECAMID 12, Vestamid L) — the default for machined stock-shape parts where moisture stability matters more than maximum stiffness. Bearings, fittings, wear strips for humid or wet service.
- SLS PA12 (PA2200, HP PA 12) — the dominant SLS / MJF material. Pick for production-quality 3D-printed end-use parts, complex geometries, low-to-mid volume bridge tooling.
- FDM PA12 — the engineering-grade FDM nylon. Pick for in-house rapid prototyping and small-batch production with FDM printers.
- Medical-grade (Vestamid Care, Rilsan Med) — USP Class VI for catheter tubing and medical devices. Industry standard.
- 30% Glass-Filled (Vestamid HT-Plus, Grilamid LV-3H) — stiffer PA12 for structural automotive parts where moisture stability matters.
- PA11 blends and PA612 — adjacent materials with similar moisture behavior but different bio-content / cost trade-offs.
Failure modes worth designing around
Insufficient stiffness for sustained-load parts. PA12 modulus is ~half PA66 dry. A PA12 gear or bracket sized for PA66 loads will deflect ~2× more — sometimes acceptable (PA12 fits typically have some compliance designed in), but design verification matters more than for stiffer plastics.
Lower max service temperature than PA6/PA66. 80–90°C continuous vs 100–110°C. Watch for parts that will see sustained elevated temperature — under-hood automotive, hot fluid systems, industrial machinery near heat sources. PA66 or higher-temp polymers are correct choices.
Cost-premium without justification. PA12 costs ~3× PA66 in stock- shape form. If neither moisture stability nor impact toughness nor the FDM/SLS process actually requires PA12, the cost premium isn’t recovering its value. Make sure the spec is driven by a real requirement.
UV degradation if unstabilized. Same caveat as other nylons — outdoor service requires UV-stabilized grades.
SLS-specific: powder aging and orientation effects. SLS PA12 part properties depend on virgin/refresh powder ratios and build orientation. For production parts, specify both.
Applications by industry
- Additive manufacturing (the #1 PA12 use case by volume) — PA2200 / Duraform PA / HP PA 12 are the dominant SLS and MJF materials globally. Engineering-grade end-use parts, complex geometries, bridge tooling, jigs and fixtures.
- Medical and pharmaceutical — catheter tubing (PA12 dominates the catheter market — flexibility, chemical resistance, low moisture uptake, USP Class VI grades), drug delivery devices, surgical instrument handles.
- Automotive fluid handling — flexible fuel lines, brake lines, hydraulic lines, quick-disconnect fittings, fuel-rail jackets. PA12’s chemical resistance to gasoline/diesel/brake fluid combined with flexibility and low moisture sensitivity makes it the industry standard for under-hood flexible tubing.
- Pneumatics and fluid power — flexible tubing, fittings, manifolds for compressed-air systems. PA12 holds dimensional stability across humidity cycles where PA6/PA66 would shift.
- Oil and gas offshore — flexible riser sheaths, subsea umbilicals. PA12 / PA11 jacket layers are standard for deepwater flexible pipe due to chemical, temperature, and moisture stability.
- Sporting goods — ski boot shells, snowshoe components, eyewear frames, athletic footwear. PA12’s combination of toughness, low temperature ductility, and chemical resistance to sweat/sunscreen is the right combination.
- Aerospace — cable conduit, low-mass interior parts, cable ties. Often paired with PA66 GF30 — PA66 for structural, PA12 for cable management.
- Electrical — cable jackets, conduit, low-voltage connectors. Better humidity stability than PA66.
- Consumer products — eyewear frames, athletic gear, hand tools.