PA / Nylon CNC Machining
Tough, wear-resistant, and vibration-dampening — the all-rounder plastic.
PA / Nylon — Tough and Versatile
Polyamide (PA), better known as Nylon, is one of the most widely used engineering plastics. Key features: excellent toughness (doesn't break on impact), good wear resistance, vibration dampening, and an affordable price.
The most important characteristic: PA absorbs moisture (up to 3% for PA6), which leads to dimensional changes and swelling. This property must be considered in design and manufacturing.
PA Grades Compared
| Type | Moisture Abs. | Stiffness | Typical Use |
|---|---|---|---|
| PA6 | 2.5–3.0% | Medium | Standard engineering parts |
| PA66 | 2.5–2.8% | Higher | Higher temperatures, stiffer |
| PA12 | 0.7–1.5% | Lower | Less swelling, more flexible |
| PA6-GF30 | 1.5% | High | 30% glass fiber, metal replacement |
Pro tip: If dimensional stability is critical, choose PA12 instead of PA6 — half the moisture absorption. Or use POM if sliding properties matter more than toughness.
Cutting Data and Moisture Management
- Cutting speed: 200–500 m/min — similar to POM
- Tools: Sharp solid carbide end mills, single-flute geometries for thin-walled parts
- Coolant: Compressed air preferred. No emulsion — PA swells in water!
- Oversize: Plan 0.1–0.3% oversize for swelling (depending on PA grade)
Moisture rule: Condition PA stock to room temperature before machining. Freshly extruded bars are dry — the finished part will swell by approximately 0.5–1.5% linearly when it reaches equilibrium moisture content.
Typical Applications
- Mechanical Engineering — Gears (quiet running!), plain bearings, chain guides
- Automotive — Clips, guides, covers (impact-resistant)
- Food Industry — Conveyor systems, scrapers, cutting boards
- Textile Machinery — Thread guides, spools, rollers
Frequently asked Questions
Why do PA parts swell?
PA absorbs water from the air — PA6 up to 3%, PA66 up to 2.8%. Water molecules insert between the polymer chains and increase the volume. Machined in a dry workshop, installed in a humid hall → dimensional change. Solution: plan oversize or choose PA12.
Which is better: PA or POM?
POM is more dimensionally stable, stiffer, and slides better. PA is tougher (doesn't break on impact), cheaper, and better for dynamically loaded parts. For gears: PA (quieter). For guide bushings: POM (more dimensionally stable).
Can PA be colored and printed?
Yes — PA is available in many colors (black, blue, gray, natural). Printing and laser marking work well. PA can also be glued and welded (ultrasonic, friction welding).
Related Topics
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