Nylon parts leave most machines with fine tool marks or a matte mold texture. A proper polishing routine upgrades that dull look to a clear, sealed surface that resists dirt and delivers visual appeal. This hands-on guide describes proven ways to polish nylon, from simple hand buffing to vapor finishing, and lists the supplies, process steps, and inspection tips you need for reliable results.
Innehållsförteckning
- Know your nylon surface before polishing
- Define the polish goal and roughness target
- Essential tools and supplies for nylon polishing
- Step-wise mechanical sanding workflow
- Use buffing compounds correctly
- Vapor and chemical smoothing options
- Vibratory tumble finishing for small parts
- Flame polish on clear nylon edges
- Surface roughness check table
- Common defects and quick fixes
- Safety and environmental notes
- Need professional help? We can finish for you
- Summary of key takeaways
Know your nylon surface before polishing
Nylon comes in many grades: PA6, PA66, glass-filled, oil-filled, and even transparent optical blends. Each grade reacts differently to friction heat and to chemical vapors.
| Nylon grade | Machining marks depth (µm) | Polish difficulty |
|---|---|---|
| PA6 natural | 5–10 | Lätt |
| PA66 heat stabilized | 6–12 | Medium |
| 30 % glass-filled PA6 | 10–20 | Hård |
| Transparent nylon blend | 4–8 | Easy but heat sensitive |
Rule of thumb: the rougher the starting finish and the harder the filler, the more sanding steps you will need before buffing.
Define the polish goal and roughness target
- Functional sealing face: aim for Ra ≤ 0.8 µm.
- Cosmetic high-gloss housing: aim for mirror or Ra ≤ 0.4 µm.
- Optical lens window: pursue Ra ≤ 0.2 µm and zero haze.
Roughness vs visual appearance
Ra ≥ 1.6 µm ████ Visible tool lines Ra 0.8–1.6 ███ Satin sheen Ra 0.4–0.8 ██ Semi-gloss Ra 0.2–0.4 █ Near mirror Ra <0.2 ░ Optical clear
Essential tools and supplies for nylon polishing
| Item | Grit or spec | Syfte |
|---|---|---|
| Waterproof sandpaper sheets | P320 → P600 → P800 → P1200 | Progressive scratch removal |
| Micro-mesh pads | 1500 → 3600 → 6000 | Pre-buff refinement |
| Cotton buff wheel | Loose-leaf 150 mm | Applies compound evenly |
| White polishing compound | Alumina bar | Cuts fine scratches |
| Plastic finish compound | Fine rouge | Final mirror glaze |
| Isopropyl alcohol | 99 % | Removes residue |
Step-wise mechanical sanding workflow
- Secure the nylon part. A soft-jaw vice prevents clamp marks.
- Wet-sand with P320 in straight strokes across the longest axis. Rinse often.
- Rotate 90° and repeat with P600. This cross-hatch helps you see remaining lines.
- Continue with P800, then P1200 using light pressure. Surface should appear matte but uniform.
- Switch to micro-mesh 1500, 3600, then 6000. The part will now look semi-gloss.
Tip: Keep water flow steady. Nylon softens if friction heat rises above 80 °C, so check by touch often.
Use buffing compounds correctly
- Charge the cotton wheel with white compound for one second—do not overload.
- Hold the part against the wheel at a 5° tilt, moving slowly side to side.
- Buff until haze disappears, then change to a clean wheel with rouge.
- Final pass lasts 10–15 seconds per square inch for optical clarity.
Vapor and chemical smoothing options
For 3D-printed nylon or complex shapes, hot solvent vapor can melt peaks without sanding.
| Solvent | Temp °C | Exposure time | Bäst för |
|---|---|---|---|
| Formic acid 90 % | 40 | 30–60 s | SLS nylon powder parts |
| Caprolactam vapor | 80 | 5–10 min | Injection molded PA6 |
Always use a sealed chamber and full PPE. Let parts cure 24 h before handling.
Vibratory tumble finishing for small parts
A bowl tumbler uses media chips and water to polish dozens of nylon pieces at once. Load parts to 60 % bowl volume. Run 4 h with plastic pyramids, then 2 h with ceramic polish cones. Rinse and dry at 50 °C.
Flame polish on clear nylon edges
- Use a micro butane torch with a soft blue cone.
- Pass 3–5 mm from edge at 50 mm/s. Do not linger.
- Allow edges to self-level. Avoid internal bubbles by limiting passes to one.
Surface roughness check table
| Inspection tool | Roughness range verified | When to use |
|---|---|---|
| Comparator coupon | Ra 0.8–3.2 µm | Shop floor quick check |
| Tactile profilometer | Ra 0.05–2.0 µm | Quality lab audit |
| Gloss meter | 60° gloss units | Cosmetic grade control |
| Optical microscope 50× | Scratch depth visual | Lens or light guide parts |
Common defects and quick fixes
| Defect | Cause | Fix |
|---|---|---|
| Swirl haze after buffing | Dirty wheel or compound overload | Re-buff with clean wheel and fine rouge |
| Orange-peel look | Skipped grit in sanding ladder | Back up two grits and repeat |
| Edge melting | Excess torch heat or friction heat | Cool part, reduce pass speed |
| White stress marks | Over-flex during clamping | Use padded jaws and steady pressure |
Safety and environmental notes
- Wear nitrile gloves—fine nylon dust irritates skin.
- Use local extraction when buffing; compounds contain aluminum oxide fines.
- Collect used water and sludge for proper disposal under local rules.
- Store solvents in a bonded cabinet; nylon vapors can ignite.
Need professional help? We can finish for you
If your project demands production-grade nylon parts ready for assembly, our facility offers CNC machining, sheet-metal work, injection molding, and in-house polishing cells. Send your drawings and let us deliver parts that shine—literally.
Summary of key takeaways
Polishing nylon is a staged process: identify the grade, step through grits, control heat, and finish with the right compound or vapor. With the tables, charts, and checklists above, you can plan a repeatable routine that hits cosmetic or functional targets every time.
