Plastic sandblasting, also called plastic media blasting (PMB), uses recycled plastic grit instead of traditional sand or mineral abrasives. The gentle action strips paint, powder coat, and surface films without gouging soft metals, carbon fiber, or composite panels. This guide explains how plastic blasting works, the tools you need, and step-by-step tips to achieve clean, damage-free parts in your shop.
Inhaltsübersicht
- What is plastic sandblasting
- Reasons to choose plastic media
- Plastic media types and grades
- Equipment setup for plastic blasting
- Key process parameters and settings
- Step-by-step blasting procedure
- Surface finish and quality checks
- Troubleshooting common issues
- Cost and productivity comparison
- Environmental and safety factors
- Maintenance and media recycling
- Häufig gestellte Fragen
- Final checklist for your shop
What is plastic sandblasting
Plastic sandblasting propels angular or cylindrical plastic grit through an air nozzle to strike the target surface. The soft grains shear paint or coatings but bounce off the base material with minimal embedment. Unlike glass bead or aluminum oxide, plastic grit is lightweight and reusable many times before breaking down.
Reasons to choose plastic media
- Removes coatings at cooler temperatures, reducing warping.
- Prevents peening on aluminum skins and thin sheet metal.
- Minimizes dust and free silica, lowering health risks.
- Allows selective stripping—paint comes off, primer may stay.
- Media can be reclaimed up to 20 cycles, cutting waste.
Plastic media types and grades
| Media resin | Shape | Typical mesh size | Mohs hardness | Main use |
|---|---|---|---|---|
| Acrylic (PMMA) | Angular | 12/16 to 30/40 | 3.5 | Aerospace paint stripping |
| Urea formaldehyde | Angular | 12/16 to 40/60 | 3.0 | Automotive powder coat removal |
| Polycarbonat | Cylindrical | 20/30 to 60/80 | 3.2 | Electronic housing deflashing |
| Melamine | Angular | 20/30 | 4.0 | High-build epoxy removal |
| Polyester | Angular | 30/40 to 60/80 | 3.0 | Composites surface prep |
Hardness chart for common blasting media
Steel grit ██████████████████ 7–8 Glass bead ██████████ 5–6 Plastic media █████ 3–4 Walnut shell ███ 2–3 Baking soda █ 1
Lower hardness means less substrate damage. Plastic sits between organic shells and glass bead.
Equipment setup for plastic blasting
| Komponente | Recommended spec for plastic media | Why it matters |
|---|---|---|
| Blast pot | Pressure vessel with 45° cone bottom | Promotes steady media flow |
| Mixing valve | Light-duty metering valve, fine thread | Plastic grit is light; needs precise feed |
| Nozzle | Boron carbide, 5–8 mm orifice, venturi style | Resists wear yet maintains velocity |
| Air supply | 7–8 bar (100–115 psi), 10 m³/min | Maintains 80–120 m/s particle speed |
| Reclaim system | Cyclone separator plus 30 µm filter | Removes dust while recirculating usable grit |
Key process parameters and settings
| Variable | Typical range | Effect on result |
|---|---|---|
| Air pressure | 50–90 psi | Higher pressure = faster strip but more heat |
| Nozzle distance | 100–200 mm | Closer gives greater cutting action |
| Nozzle angle | 30–60° to surface | Low angle peels paint; 90° digs deeper |
| Media flow rate | 1–2 kg/min | Too high wastes grit and lowers visibility |
| Part temperature rise | <15 °C preferred | Keep below distortion point of thin alloy |
Step-by-step blasting procedure
- Verify the coating type and thickness. Pick a compatible plastic media mesh.
- Load clean media into the blast pot. Fill no more than two-thirds to prevent surging.
- Set air pressure at the regulator. Start low (60 psi) and adjust after a quick test pass.
- Hold the nozzle 150 mm from the workpiece at a 45° angle. Sweep steadily at 200 mm per second.
- Check coating removal every pass. Increase pressure 5 psi if paint does not lift.
- When base metal or primer appears uniformly, stop and blow off dust with low-pressure air.
- Inspect the surface with a 10× loupe. Look for gouges or remaining paint edges. Touch up spots as needed.
Surface finish and quality checks
Use the table to match your target roughness.
| Media mesh | Typical Ra µm | Common follow-up process |
|---|---|---|
| 12/16 | 5–6 | Re-coat with thick epoxy |
| 20/30 | 3–4 | Primer then top-coat paint |
| 40/60 | 1–2 | Adhesive bonding surface |
| 60/80 | 0.8–1.2 | Clear coat or cosmetic finish |
Troubleshooting common issues
| Problem | Likely cause | Solution |
|---|---|---|
| Uneven paint removal | Variable nozzle distance | Install a swing arm for constant standoff |
| Media clogs in hose | Moist air or damp grit | Run air dryer and oven-dry media |
| Surface pitting on aluminum | Air pressure too high | Drop pressure 10 psi and widen sweep |
| High dust in cabinet | Poor cyclone tuning | Adjust vortex to pull fines only |
Cost and productivity comparison
| Parameter | Plastic media | Glass bead | Aluminiumoxid |
|---|---|---|---|
| Media cost per kg | $2.50 | $0.90 | $1.10 |
| Average reuse cycles | 15–20 | 5–8 | 3–5 |
| Strip rate m²/h (paint) | 5–8 | 4–6 | 6–9 |
| Dust generation | Niedrig | Mittel | Hoch |
| Surface damage risk | Very low | Niedrig | High on soft alloys |
Environmental and safety factors
- Plastic grit contains no free silica, reducing silicosis risk.
- Collect spillage quickly; pellets can create slip hazards.
- Wear a full hood, P-APR with P100 filters, gloves, and ear protection.
- Check local rules—some states classify used paint-laden plastic grit as non-hazardous if lead-free.
Maintenance and media recycling
- Sieve reclaimed media through 20-mesh screens every 2 hours of blast time.
- Vacuum cabinet corners weekly to remove paint chips and fines.
- Inspect nozzle for wear—replace when diameter grows 1 mm over nominal.
- Store fresh media in sealed drums to block moisture.
Häufig gestellte Fragen
Can I strip powder coat with plastic grit?
Yes. Use coarse 12/16 acrylic at 80–90 psi. Expect slower rate than oxide but zero gouge.
Will plastic blasting remove rust?
It will lift loose rust but will not cut deep scale. Switch to crushed glass or oxide after paint is off.
Is plastic media safe on carbon fiber panels?
Yes, with fine 60/80 polycarbonate at 40 psi and 200 mm nozzle distance. Always test a scrap piece first.
Final checklist for your shop
- Select media resin and mesh by coating hardness and substrate.
- Dry air supply to under 10 % humidity.
- Dial in 60–70 psi to start; adjust based on removal speed and surface feel.
- Keep nozzle 150 mm away at a 45° sweep pattern.
- Monitor part temperature—pause if it feels hot to the touch.
- Recycle grit through cyclone until fines drop cutting speed, then add 20 % new media.
Follow these steps to harness plastic sandblasting for quick, clean, and substrate-friendly coating removal in your own workshop or production line.
