2.3 Compressed Air Standards (ISO 8573)
Compressed air is the "Fourth Utility," but unlike electricity or water, you manufacture it on-site. If your air quality fails, you are injecting pollution directly into your precision equipment.
Pneumatic actuators in pick-and-place heads operate at millisecond speeds. Contaminants (water, oil, dust) cause Stiction—the friction that kills repeatability. A 0.1-second valve delay turns a perfect placement into a skewed defect.
The ISO 8573-1 Standard (Class 1.2.1)
Do not ask for "Clean Dry Air." That is a subjective wish.
Demand ISO 8573-1 Class 1.2.1. This is the engineering definition of "clean" for electronics.
1. Solids (Class 1):
- Limit: < 100 particles (0.1 – 0.5 µm) per m³.
- The Risk: SMT vacuum nozzles have internal filters with 10 µm mesh. Class 1 particulates pass right through and grind against the solenoid spool, causing premature wear.
2. Water (Class 2):
- Limit: Pressure Dew Point (PDP) ≤ -40°C.
- The Physics: As compressed air expands at the point of use, it cools rapidly (Joule-Thomson effect). If the dew point is not low enough, invisible vapor turns into liquid water.
- Consequence: Water washes away the "lifetime grease" inside pneumatic cylinders, leading to rust and seizure.
3. Oil (Class 1):
- Limit: Total Oil Content ≤ 0.01 mg/m³.
- The "Silent Killer": Oil mist atomizes at the exhaust port of the machine. It settles on optical sensors and camera lenses, slowly blinding the machine's vision system.
- Control: Use Oil-Free compressors. If using oil-injected screw compressors, active carbon towers are mandatory.
Filtration Architecture
You cannot filter a problem away at the end of the pipe. You must treat it in stages.
- Compressor Room: Water Separator -> Refrigerant Dryer -> Coalescing Filter.
- Point of Use (Machine): Desiccant Dryer (to hit -40°C) -> Active Carbon (Oil) -> Dust Filter.
Final Checklist
Parameter | Specification (ISO 8573) | Critical Failure Mode |
Particulates | Class 1 (0.1 – 0.5 µm) | Valve / Cylinder abrasion |
Water (Dew Point) | Class 2 (≤ -40°C) | Rust / Lubricant Washout |
Oil Content | Class 1 (≤ 0.01 mg/m³) | Lens/Sensor Fogging |
Filter Service | Based on ∆P (Pressure Drop) | Logged |