What is polyamide?
Polyamide (PA) is a synthetic engineering plastic whose molecular chains contain amide bonds (–CO–NH–). This molecular structure gives polyamide its characteristic combination of mechanical strength, excellent wear resistance, good impact toughness and self-lubricating sliding properties. Polyamides are thermoplastics — they can be extruded, injection-moulded and machined, making them perfect for both volume production and precision part manufacture.
The polyamide family is divided into several grades by a numerical code. The most common in industry are PA6, PA66, PA11, PA12 and PA46. The most widely sold machinable semi-finished products are PA6 (extruded thermoplastic) and PA6G / Cast PA (cast polyamide for large parts).
Polyamide vs Nylon — what's the difference?
In practice, none. Nylon was originally a trade name coined by DuPont (1935), and today both terms are used interchangeably. Polyamide is the scientific name for the material family; nylon is the everyday trade name. The textile industry typically uses "nylon" (stockings, toothbrushes, ropes), while engineering plastics use the official "polyamide" or its abbreviation PA.
Worth knowing: PA6 and PA66 are different chemical structures, not just grade variants. Read the differences below — picking the wrong one can mean a short service life or an over-specified material.
How is polyamide produced?
Polyamide is produced by polymerising amide-containing monomers. The number or numbers in a PA grade name describe the carbon atom count of the monomer units: PA6 is based on six-carbon caprolactam, while PA66 and PA46 are made from two separate monomer units (e.g. PA66 = hexamethylenediamine + adipic acid, both six-carbon). Raw materials are mostly oil-based, but bio- and recycled-content grades (e.g. PA11 from castor oil) are increasingly available.
Polyamide grades — which one fits your application?
We supply the six most common polyamide grades, each optimised for different applications. Below is a quick guide — you can also ask us for a material recommendation based on your application.
Most common grade
PA6 (Nylon 6)
The most common polyamide in industry — extruded, easy to machine. Excellent impact strength and wear resistance. Suitable for general machinery parts: gears, bushings, rollers. 24-hour water absorption typically 0.3–1.0 % — significantly more at saturation. Dimensional stability needs to be considered in precision parts.
Higher performance
PA66 (Nylon 6.6)
Stiffer and stronger than PA6, higher melting point (255 °C vs PA6's 220 °C) and continuous service temperature around 100 °C. Good wear resistance, though final performance depends on load, mating surface and lubrication. Typical choice for automotive components and demanding bearing applications.
Large parts
PA6G / Cast PA
Cast polyamide — available in large stock sizes (rods up to Ø 800 mm, plates up to 2 000×1 000 mm). More uniform structure with fewer internal stresses than extruded grades. Ideal for large machined parts, pulleys and wear strips.
Dimensionally stable
PA12 (Nylon 12)
Absorbs only 0.3–0.4 % moisture — much less than PA6. The most dimensionally stable polyamide. Excellent chemical resistance and low friction. Used in pneumatic tubing, fittings and other parts where dimensional accuracy is critical.
Wear resistant
PA6 + MoS₂
Molybdenum disulfide-filled PA6 — better slide and wear properties than standard PA6. Typically dark in colour (black or grey). Used in bearings and slide bushings.
Self-lubricating
Oil-filled PA6
Polyamide with built-in oil — self-lubricating, low-friction bearing material. Works without external lubrication. Colour varies by manufacturer (often green or blue).
Food contact
PA6 FDA / EU 10/2011 grades
Polyamide grades compliant with food-contact requirements. Available in natural and blue (detection-aided for HACCP lines). Conveyor parts, cutting boards, packaging machinery guides, beverage industry components. Suitability is confirmed via material-specific documentation.
PA grade comparison
| Property | PA6 | PA66 | PA6G (Cast) | PA12 |
| Tensile strength | 70–85 MPa | 80–90 MPa | 70–80 MPa | 50–60 MPa |
| Melting point | 220 °C | 255 °C | 220 °C | 178 °C |
| Continuous service temp | ~80–100 °C | ~100 °C | ~90 °C | ~80 °C |
| Water absorption (24 h) | 0.3–1.0 % | 0.5–1.0 % | 0.3–0.7 % | 0.1–0.2 % |
| Impact strength | Excellent | Good | Excellent | Good |
| Machinability | Good | Good | Excellent | Very good |
| Typical use | General parts | Automotive, hot | Large parts, machining | Pneumatics, chemicals |
Polyamide technical properties
Polyamide is one of the most versatile engineering plastics — its mechanical properties cover a wide range of applications. Typical values for PA6 are shown below; specific data sheets are supplied on request.
| Property | Value | Standard / note |
|---|
| Density | 1.14 g/cm³ | ISO 1183 |
| Tensile strength | 70–85 MPa | ISO 527 |
| Tensile modulus | 3 200 MPa | ISO 527 |
| Elongation at break | 15–80 % | ISO 527 |
| Charpy impact (notched) | 4–10 kJ/m² | ISO 179 |
| Shore D hardness | 80–85 | ISO 868 |
| Continuous service temp | ~80–100 °C (PA6) / ~100 °C (PA66) | Short-term up to 160 °C; exact value depends on grade |
| Melting point | 220 °C | PA6 (PA66: 255 °C) |
| Friction coefficient (dry, steel) | 0.3–0.4 | Self-lubricating |
| Volume resistivity | 10¹³ Ω·cm | Good insulator, affected by moisture |
| Water absorption (24 h) | 0.3–1.0 % | PA6 (ISO 62) |
| Water absorption (saturation) | 7–9 % | Long-term, affects dimensions |
| Flammability | HB | UL 94 (V-2 grades available) |
Note on moisture: Polyamide is hygroscopic — this is the most important design consideration. PA6's 24-hour water absorption is typically 0.3–1.0 %, but at saturation values can be significantly higher (7–9 %). Dry PA is stiffer but more brittle; moist PA softens and dimensions change. For tight-tolerance applications, account for moisture effects in fit and clearances.
Typical polyamide applications
Polyamide is used in practically every industry. The most common applications are parts that require wear resistance, impact toughness and the ability to operate without external lubrication. Below the most-requested applications:
Gears and pinions
PA's self-lubricating surface and wear resistance make it an ideal choice for light- to medium-load gearboxes. Corrosion-free and quieter than metal gears.
Bearings and bushings
The classic PA application. Operates without external lubrication at low and medium rotational speeds. Oil-filled PA6 and MoS₂-filled PA6 extend service life further.
Conveyor rollers and guides
PA rollers and guide rails in packaging lines, breweries and food production. FDA grades ensure food-contact safety.
Wheels and sheaves
Cast PA for large wheels and pulleys (up to Ø 800 mm). Lighter than metal, corrosion-free and dampens impact.
Wear strips and guides
PA sheets and strips in chutes, hoppers and sliding surfaces. Reduces friction; replaceable wear parts.
Pneumatic components
PA12's low water absorption makes it dimensionally stable — ideal for pneumatic fittings, tubing and valve components.
Insulating and electrical parts
PA is a good electrical insulator — used in connectors, cable protection sleeves and insulation plates. Flame-rated grades (e.g. UL 94 V-0) are available as specialty grades; halogen-free status is always verified from material-specific documentation.
CNC-machined precision parts
PA6 and PA66 machine excellently — we supply finished components per customer drawings through our partner network. Read about machining service.
Polyamide vs other engineering plastics
Polyamide is not always the best choice — it depends on the application. Here's a quick comparison against common alternatives:
| Property | Polyamide (PA6) | POM | PEEK | UHMW-PE |
|---|
| Service temperature | 80–100 °C | 100 °C | 260 °C | 80 °C |
| Tensile strength | 70–85 MPa | 65 MPa | 100 MPa | 22 MPa |
| Water absorption (24 h) | 0.3–1.0 % | 0.2 % (low) | 0.1–0.5 % | <0.01 % (negligible) |
| Friction coefficient | 0.3–0.4 | 0.2–0.4 | 0.3–0.4 | 0.1–0.2 (lowest) |
| Impact strength | Excellent | Good | Very good | Excellent |
| Wear resistance | Excellent | Excellent | Excellent | Best |
| Best for | General engineering | Tight tolerances | High temperature, chemistry | Slide surfaces, wear |
Summary: Choose PA when you want a versatile material that resists impact and wear. Choose POM when you need tight tolerances (PA absorbs moisture). Choose PEEK when temperature exceeds 100 °C or chemicals are aggressive. Choose UHMW-PE when you need the lowest friction and best slide wear.
Available forms and sizes
We supply polyamide in various forms from stock or to order. Typical delivery formats:
| Form | Stock sizes | Custom | Grade |
|---|
| PA rod | Ø 6 – Ø 300 mm | Cast PA up to Ø 800 mm | PA6 extruded / PA6G cast |
| PA sheet | 2 – 100 mm thick, 610×1 000 / 1 220×2 440 mm | Cast PA up to 300 mm thick | PA6 / PA6G / PA66 |
| PA tube | inner Ø 30 – 250 mm | To dimensions | PA6 extruded |
| PA machined parts | Per customer drawing | Prototypes and series | All grades |
Colours and special treatments
- Natural / cream: standard PA6 and PA66
- Black: carbon-filled (improved UV resistance)
- Blue: food-line detection (HACCP)
- Green / blue: typically oil-filled PA6 (bearing applications, manufacturer-dependent)
- Dark grey / black: MoS₂-filled PA6 (improved slide wear)
- FDA / EU 10/2011 grades: natural and blue. Suitability is verified from material-specific documentation
- Glass-filled PA-GF30: 30 % glass fibre — stiffer, stronger, but more brittle
Polyamide machining — tips for designers
Polyamide machines excellently on standard CNC equipment. A few technical notes:
- Tooling: Use carbide tools — they hold an edge longer than HSS. Minimum cutting-edge radius 0.4 mm.
- Cutting speeds: Turning 100–500 m/min, milling 200–800 m/min. PA tolerates higher speeds than POM.
- Cooling: Compressed air is sufficient for most applications. Emulsion coolant increases moisture absorption — avoid for tight-tolerance parts.
- Internal stresses: Extruded PA6 can contain residual stresses. For large machined parts, Cast PA is recommended for its stress-free structure.
- Dimensional stability: Allow a machined PA part to equilibrate with ambient humidity before tolerance measurement — typically 24–72 hours.
- Bonding: PA does not bond easily — use surface treatment (plasma, corona) or mechanical joints. Welding is possible between matching PA grades.
Polyamide challenges and how to manage them
Polyamide is versatile, but not for every application. The main challenges to be aware of:
1. Water absorption
PA6's 24-hour water absorption is typically 0.3–1.0 %, but with long-term moisture exposure (saturation) values can rise significantly — typically 7–9 %. Moisture affects dimensions and softens the material. Solution: use PA12 for precision parts, account for moisture in tolerances, and store parts in dry conditions before installation.
2. UV and weather resistance
Natural PA becomes brittle under long-term UV exposure outdoors. Solution: use carbon-filled (black) PA or UV-stabilised grades for outdoor applications.
3. Strong acid resistance
Polyamide tolerates weak acids and alkalis but not strong mineral acids. Solution: for aggressive chemistry, choose PTFE, PVDF or PEEK.
4. High temperature
PA6 sustains ~80–100 °C continuously and PA66 typically around 100 °C. Short-term excursions are possible but strength drops. Solution: for sustained service above 120 °C, use PEEK or PAI.
Polyamide industries
Polyamide is used across virtually all industrial sectors. The most common customer segments that order PA rods, sheets and machined parts from us:
- Mechanical engineering: gears, bearings, bushings, guides, jigs
- Food & beverage: conveyor rollers, cutting boards, packaging machinery parts (FDA / blue)
- Automotive: under-bonnet components, cooling system parts (PA66-GF30)
- Agricultural machinery: wear strips, towing components, bushings (Cast PA)
- Pulp & paper: wear parts, guides, sheaves
- Pneumatics: fittings, valve bodies, dimensionally stable components (PA12)
- Textile machinery: yarn guides, spools, wear strips
- Packaging industry: chutes, hoppers, guide bars
