The short answer
Unfilled nylon 6 injection grades typically run about 1.13 g/cm³ density, 3.0–3.5 GPa tensile modulus and 80–90 MPa yield strength dry as molded, falling to about 1.0–1.2 GPa and 40–45 MPa once conditioned at 23°C / 50% RH. Notched impact goes the other way, from about 4–5 kJ/m² dry to about 20–50 kJ/m² conditioned. PA6 takes up about 2.6–3.4% moisture at 50% RH, so compare data sheets on the same basis. It melts at about 220°C / 428°F.
Have a part number or drawing callout?
Paste it as written. A polymer chemist will tell you which grade it calls for, suggest equivalents and quote it by email.
This page covers unreinforced PA6 for injection molding. Full typical values are on PA6 properties, the overview is on nylon, and the trade-offs against PA66 are in nylon 6 vs. nylon 66.
Typical spec window
| Property | Typical range | Test method |
|---|---|---|
| Viscosity | Viscosity number about 130–150 cm³/g (some U.S. sheets use relative viscosity instead) | ISO 307 (ASTM D789 for relative viscosity) |
| Density | About 1.13 g/cm³ | ASTM D792 or ISO 1183 |
| Tensile strength at yield, dry / conditioned | 80–90 / 40–45 MPa (11,600–13,000 / 5,800–6,500 psi) | ISO 527 or ASTM D638 |
| Tensile modulus, dry / conditioned | 3.0–3.5 / 1.0–1.2 GPa (435,000–510,000 / 145,000–175,000 psi) | ISO 527 |
| Charpy notched impact, 23°C, dry / conditioned | 4–5 / 20–50 kJ/m² | ISO 179/1eA |
| Heat deflection, 1.8 MPa, dry | 60–65°C / 140–149°F | ISO 75 or ASTM D648 |
| Melting point | About 220°C / 428°F | ISO 11357 or ASTM D3418 |
| Moisture absorption | 2.6–3.4% at 23°C / 50% RH; 9–10% saturated in water | ISO 62 |
| Flammability | V-2 typical for unfilled natural grades | UL 94 or IEC 60695-11-10 |
Typical ranges from published data sheets for grades in this window; dry means dry as molded and conditioned means equilibrium at 23°C / 50% RH. Your grade’s own data sheet and the lot COA are what count.
What it’s used for
- Clips, fasteners and cable clamps
- Housings, grips and handles for tools and appliances
- Light-duty gears, bushings and rollers
- Fittings and small mechanical parts
- Automotive interior clips and brackets
- Consumer and sporting goods parts
How to tell grades apart
- Viscosity. Low-to-medium viscosity grades (viscosity number around 130–150 cm³/g, such as Akulon F223-D and Ultramid B3S) are the usual injection choice. Higher-viscosity PA6 is for extrusion, film and tough thick parts.
- Nucleated and lubricated. Nucleated grades crystallize faster for shorter cycles. BASF describes B3S as finely crystalline for very fast processing. Lubricated grades help ejection and feeding. Both change how the grade runs, so keep the same package once a part is approved.
- Heat stabilized. Heat-stabilized grades resist long-term oxidation at elevated temperature, for hot-air or under-hood service. Unstabilized grades are fine for room-temperature parts. The data sheet or the UL RTI tells you which you have.
- Dry vs. conditioned data. Producers show two columns. Dry values look stiffer and stronger. Conditioned values show the toughness and lower stiffness a part has in service. Compare like with like.
- Not GP. Glass-filled, impact-modified, flame-retardant and PA66 grades are separate families. PA66 melts about 40°C higher and needs a hotter process.
What to put on your RFQ or PO
- Polymer. PA6 stated in writing, so PA66 or a blend is not substituted.
- Viscosity. Viscosity number or relative viscosity, with the test method, nominal value and range.
- Additive package. Heat stabilized, nucleated, lubricated or none.
- Property basis. Say whether your property limits are dry as molded or conditioned.
- Color. Natural, black or a color code, and whether you add masterbatch.
- Approvals. FDA, UL or automotive specs, with the producer’s letter for the exact grade and color.
- COA values to check. Viscosity on each lot, and moisture as shipped if the producer reports it.
- Packaging. Sealed moisture-barrier bags or lined gaylords. PA6 ships dry and picks up moisture quickly once opened.
- Quantity and release size. Total quantity, how much per release and how often.
A polymer chemist reviews every request and checks the grade against your process before we quote. Every prime lot from our suppliers ships with a COA, and orders start at one gaylord.
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- Same viscosity and additive package from another producer. Ultramid B3S, Akulon F223-D and Durethan B30S sit in this window. Check shrinkage, cycle time and color on first articles.
- Nylon 66. Higher melting point and more stiffness at temperature, with a hotter process. See nylon 6 vs. nylon 66 and Zytel 101L.
- Impact-modified nylon. For cold impact and snap fits. See impact-modified nylon.
- Glass-filled PA6. For stiffness and heat under load. See Ultramid B3WG6 and PA6 GF30 properties.
- Nylon 12 or acetal. Where moisture growth is a problem. See nylon 12 vs. nylon 6 and acetal vs. nylon.
Common processing problems
- Parts grow or soften with moisture: nylon swelling moisture
- Silver streaks from wet resin: splay silver streaks
- Brittle parts right out of the mold: brittle cracking parts
- Resin left open at the press: resin storage moisture
- Drool and stringing at the nozzle: stringing drool
Common questions
What is the difference between dry-as-molded and conditioned nylon 6?
Dry-as-molded values are tested right after molding, with almost no moisture. Conditioned values are tested after the part reaches equilibrium at 23°C / 50% RH, about 2.6–3.4% moisture for PA6. Conditioned PA6 has roughly a third of the dry stiffness but many times the notched impact.
Does nylon 6 need to be dried?
It ships dry in sealed packaging and can run from a freshly opened bag. Once exposed, dry it, for example about 4 hours at 80°C / 176°F in a dehumidifying dryer, to 0.15% moisture or less. Check your grade’s data sheet for its limit.
Why are my nylon 6 parts brittle right after molding?
Fresh parts are dry and less tough. They gain impact strength as they absorb moisture. If parts must pass impact tests at once, condition them, and check for wet resin, long residence time or too much regrind.
Should I choose nylon 6 or nylon 66?
PA6 processes at lower temperatures, is somewhat tougher and often costs less. PA66 holds stiffness better at higher temperatures. The nylon 6 vs. nylon 66 page covers the trade-offs in detail.
Tell us the grade you run now
A polymer chemist reviews every request, then matches your grade or finds a qualified equivalent and prices it.
What to send for an accurate quote
- The grade name, from any supplier, or a data sheet
- Color (natural, black or a custom match)
- Fill type and percentage, if any
- Melt flow, if you know it
- Quantity for this order and what you use in a year
- Ship-to city and state or province