Nylon 6/6 (PA66)

Complete property data sheet for unfilled Nylon 6/6 — mechanical, thermal, electrical and physical values, each with its ASTM test method — plus the moisture effect that makes nylon different from every other engineering plastic.

Data verified 2026-09-29 · based on ASTM D4066-13(2019)

Mechanical Properties

Thermal Properties

Electrical & Physical Properties

Unfilled vs 30% Glass Filled Nylon 6/6

Adding glass fibre to nylon 6/6 roughly triples the tensile strength and quadruples the modulus, at the cost of elongation, impact strength and machinability. The choice between them is usually the first decision in a nylon part.

Weight & Volume Calculator

Machining Nylon 6/6

Nylon 6/6 cuts easily but not simply. It is soft and has a low softening point, so a dull tool or an excessive surface speed generates enough friction to melt the chip, which then welds to the edge and tears the surface. Use sharp, polished, high-rake tooling, generous clearance, high feed per tooth and moderate speed; the goal is to cut the material off, not to rub it away.

The dimensional problem is bigger than the cutting problem. Nylon absorbs 1.2–1.5% of its weight in water over 24 hours and reaches equilibrium around 2.5% at 50% relative humidity. Absorbed water acts as a plasticiser: the material swells, and a machined part grows roughly 0.5–1.5% linearly between the dry-machined state and the conditioned state. A 100 mm part can move over a millimetre. Either machine to the conditioned state (condition the stock first, by soaking it in water or leaving it in a controlled humidity room), or accept and design around the movement. Do not machine dry stock to a tight tolerance and expect it to hold in service.

Nylon also has very high elongation and low stiffness, so thin walls deflect away from the cutter. Support the work, take light finishing passes, and expect to deburr by hand or with a sharp scraper — a sanding belt will smear rather than cut the burr off.

Where Nylon 6/6 Is the Right Choice

Nylon 6/6 is the default engineering plastic for mechanical parts that must take impact and sliding wear without lubricant. It has the best combination of toughness, abrasion resistance and cost of any unfilled engineering plastic, and it survives repeated shock loading that would crack a stiffer material such as Delrin or acrylic.

Its constraints are equally clear. Moisture absorption is the first: it swells with humidity and shrinks when dry, so parts requiring tight dimensional stability over changing conditions are a poor fit. Temperature is the second: the 105 °C continuous rating sounds generous, but the deflection temperature under load at 1.8 MPa is only 75 °C, and strength falls steadily as temperature rises. Chemical resistance is good against oils, greases and fuels, and poor against strong acids and phenols.

Against the alternatives: Delrin (POM-H) is stiffer, far more dimensionally stable and easier to hold to tolerance, but less resistant to impact and to repeated loading; PEEK is stronger and survives 250 °C continuously, at 8–12× the cost; UHMW-PE has better abrasion resistance but only 80 °C of service temperature and no stiffness at all. Nylon 6/6 occupies the middle — the cheapest way to get real mechanical toughness.

How to Read This Data Sheet

Values are typical published figures for unfilled, natural-grade Nylon 6/6, measured on standard test specimens. Every row names the test method it came from, because a polymer property without its test method is not a comparable number — tensile strength measured to ASTM D638 and to ISO 527 differ systematically, and impact values depend heavily on specimen geometry.

Two caveats apply to every figure here. First, temperature: polymer properties are far more temperature-sensitive than metal properties, and a tensile strength quoted at 23 °C tells you little about the same material at 100 °C. Second, conditioning: hygroscopic plastics such as nylon absorb moisture from the air, and absorbed water acts as a plasticiser — the same grade can be stiff and strong when dry and significantly tougher but weaker when conditioned. Where a property is strongly affected by moisture, the row notes it.

Filled, reinforced, lubricated and impact-modified grades of the same base polymer differ substantially from these figures. Use this page to compare materials and to shortlist; use the specific grade's data sheet for design calculations.

Frequently Asked Questions

What is the density of Nylon 6/6?

1.14 g/cm³, which is lighter than water — one of the few engineering plastics that floats. Density matters for two practical reasons: it sets the weight of a finished part through the material's cost per kilogram, and it is the number this page's weight calculator uses to convert a volume into a mass.

Can Nylon 6/6 be machined?

Nylon machines cleanly with sharp, high-rake tooling and generous clearance, but it is soft and springy — a dull edge rubs and melts rather than cuts, and the burr it leaves is difficult to remove. Dimensions cut dry will change as the part absorbs moisture from the air.

How do I choose between Nylon 6/6 and another engineering plastic?

Choose Nylon 6/6 when you need a tough, abrasion-resistant, inexpensive plastic with good fatigue life — gears, bushings, rollers, wear pads — and when a small amount of dimensional movement with humidity is acceptable.

Why does nylon change size, and by how much?

Nylon absorbs water from the atmosphere, and the absorbed water pushes the polymer chains apart. A part molded or machined dry will grow roughly 0.5–1.5% linearly as it reaches equilibrium at typical indoor humidity — around 2.5% moisture by weight. A 100 mm dimension can move more than a millimetre. Condition the stock to the expected service environment before final machining, or design the tolerance around the swell.

Does nylon 6 or nylon 6/6 machine better?

Nylon 6/6 is marginally better to machine because its higher melting point and crystallinity give it a little more stiffness as the tool passes, so it smears less. The difference is small next to the effect of tool sharpness. Nylon 6 absorbs slightly more moisture and has a lower melting point; choose between them on temperature and cost rather than on machinability.

Is nylon food safe?

Several nylon 6/6 grades carry FDA food-contact listings, but food-contact status is grade-specific — it depends on the additives, lubricants and colourants in that particular compound, not on the polymer family. Confirm the specific grade's regulatory documentation before using it in food handling equipment.

Related

• Delrin (POM-H) Properties
• PTFE Properties
• PEEK Properties
• Delrin vs Nylon — Which to Choose
• Plastic Service Temperature Chart
• Plastic Machining Tolerance Chart

Value Sources

Each data column on this page is tied to the source it came from. The numbers in square brackets correspond to the table headers above.

Data Sources

Cross-checked against:

• Published Nylon 6/6 stock-shape and resin data sheets from two independent suppliers
• Dry-as-molded and conditioned values checked against a third supplier's conditioning data
• Glass-filled comparison values cross-checked against a 30% GF grade data sheet

Values are typical published figures for unfilled, natural-grade resin at 23 °C, dry as molded unless the row states otherwise. They are not specification minima. Design to the specific grade's data sheet, and derate for the service temperature and moisture condition the part will actually see.

Cite This Page

Every value on this page is traceable to the sources listed above. If you use the data in a document, paper or report, cite it as:

Each row in the tables above also has a permanent link — hover a row and use the # link to cite a single value rather than the whole page.