PA6 nylon
Specify polyamide 6 by grade, manufactured form and moisture state; interpret dry/conditioned properties, dimensional changes and long-term service requirements.
Tags: materials, polymers, nylon, pa6, polyamide
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Identify the grade, form and moisture state
BASF Ultramid B3S R03 PA6 gives typical ISO 527-1/-2 tensile modulus of 3,500 MPa dry and 1,200 MPa conditioned for uncolored material at 23°C. Yield stress is 90 MPa dry and 45 MPa conditioned. Carry the conditioning and product form into any comparison. BASF B3S R03 datasheet
PA6 is polyamide 6, one member of the semi-crystalline nylon family. It is distinct from PA66 and from modified, lubricated or reinforced nylon grades. Mitsubishi Chemical Group supplies different PA6/PA66 stock-shape formulations for bearing and wear applications; the family name alone does not identify a complete engineering material. MCG nylon overview
Moisture changes more than mass
MCG explains that nylon absorbs moisture from its surroundings, which can change dimensions and mechanical and electrical properties. Its comparison associates the PA6 data with standard unfilled Nylatron™ MC 901 unless otherwise stated. A water-absorption number needs its duration, temperature and specimen/product context. MCG moisture and property scope
For a fit, account for humidity, immersion, temperature, section thickness and exposure time. Do not convert percentage mass uptake directly into an equal percentage linear expansion. Establish the relevant dimensional response from the material supplier or representative parts. A dimension accepted in a dry inspection room may not represent a wet-service clearance.
Separate resin drying before processing from conditioning a finished part. The former establishes an appropriate feedstock state; the latter establishes a state for testing or use. Neither can be replaced by an undocumented wait in ambient air. Record the applicable method and acceptance criterion.
Named molded-resin example: B3S R03
BASF's Ultramid® B3S R03 sheet identifies an easy-flowing injection-molding PA6 grade. For uncolored product at 23°C, its typical ISO 527-1/-2 data list:
| Quantity | Dry | Conditioned |
|---|---|---|
| Tensile modulus | 3500 MPa | 1200 MPa |
| Yield stress | 90 MPa | 45 MPa |
| Yield strain | 4% | 20% |
Keep the grade, specimen basis and dry/conditioned distinction. The table does not itself define the complete conditioning protocol, so obtain it before using these columns as an acceptance test. BASF B3S R03 product information, 09/2026
As original arithmetic on those typical values, the conditioned-to-dry modulus ratio is 1200/3500 = 0.343, or approximately 34.3%. This is not a universal moisture knockdown factor for PA6 or a prediction of the finished part's stiffness. Geometry, grade, orientation, temperature and time under load still matter.
BASF separately lists 2.6–3.4% equilibrium moisture absorption at 23°C/50% RH and 9–10% saturation water absorption at 23°C, both by methods similar to ISO 62. Do not equate atmospheric equilibrium with immersion saturation or silently assign either preparation to every mechanical result. BASF absorption conditions
Stock shapes require their own evidence
Ensinger's TECAMID 6 natural sheet identifies extruded stock-shape data unless otherwise noted. It gives 70 MPa tensile strength at 5 mm/min by ASTM D638 and 2800 MPa tensile modulus at the same rate, with a type-1 tensile specimen note. These comparison guidelines are not guaranteed minima or maxima. Ensinger stock-shape sheet
Do not average these entries with BASF's molding-grade values or choose the larger value as a generic PA6 property. Confirm the temperature and moisture state required by the project when the cited sheet does not fully define them. Separate stock acceptance from final machining, dimensional and functional acceptance.
For machining, establish material-removal sequence, workholding, heat control and any supplier-recommended intermediate treatment. Protect critical geometry from distortion and inspect after the specified conditioning. For molding, qualify the current grade's processing instructions, tool geometry, shrinkage and weld-line effects. For cast stock, obtain the relevant manufacturer's data and traceability rather than treating extruded stock as an equivalent.
Temperature, sustained loading and wear
BASF lists a 220°C DSC melting temperature, while its HDT entries differ with test stress: 65°C at 1.8 MPa and 180°C at 0.45 MPa. These test results are not continuous loaded-part operating limits. BASF thermal test table
For bearings, gears or wear pads, define the mating material, surface, lubrication, contamination, pressure, speed, duty cycle and heat removal. A wear-resistant or self-lubricating description does not establish a universal dry-running allowance. Qualify the actual pair and geometry, including moisture-related changes in fits and backlash.
Chemical exposure and release
MCG notes nylon's useful resistance to many oils and fuels while identifying limitations with acids and hot washing or prolonged moisture exposure. Apply such family guidance as a screening step, then confirm the actual grade against the fluid formulation, concentration, temperature, stress and exposure duration. MCG chemical guidance
Specify joining, inserts and fasteners as assembly processes with their own acceptance. Evaluate local stresses and retained function after environmental exposure. Material tensile strength alone cannot qualify a bond, thread or interference fit. Obtain product-specific declarations where food contact, electrical or other approvals matter.
Retain grade, lot, form, process/drawing revision, moisture/conditioning record and required dimensional and functional results. Review substitutions against all of these requirements.
Sources reviewed November 1, 2026. BASF's retrieved product-information PDF prints 09/2026. Ensinger's cited regional sheet prints 2017/06/01, Version AA. MCG's comparison page supplies no explicit technical revision date. Upload paths and search-result dates are not substituted for these source dates.