"IP67" is one of the most quoted — and most misunderstood — specifications in industrial motion. Here is what it actually guarantees, and what it doesn't, when applied to encoders.
Decoding the IP rating
The IP code has two digits: the first (6) rates protection against solids, the second (7) rates protection against liquids.
| Digit | Meaning |
|---|---|
| 6 (solids) | Dust-tight — no ingress of dust under test conditions |
| 7 (liquids) | Protected against temporary immersion in water (up to 1 m for 30 minutes) |
So an IP67 encoder is dust-tight and survives temporary immersion — which covers washdown, condensation, splash and most oily industrial environments. It is not rated for continuous submersion (that would be IP68) or high-pressure jets (IP69K).
Why IP rating alone isn't enough
A sealed housing keeps water out, but the sensing technology inside still has to work in that environment. Two failures IP67 cannot fix:
- Contamination inside the sensing path: optical encoders rely on a clear light path; moisture or oil film inside degrades them even in a sealed unit.
- Condensation: temperature cycling can create condensation inside a sealed housing. Inductive sensing is unaffected by moisture — there is no optics to fog.
The full environmental picture for encoders
Beyond ingress, field reliability depends on:
- Temperature: −40 to +85 °C operating range vs 0–50 °C for many optical units.
- ESD immunity: ±12 kV (IEC 61000-4-2) for electrically noisy machines.
- Vibration and shock: tested to 10 Hz–2 kHz and 980 m/s².
- Humidity: 95% RH, 96-hour soak without performance shift.
Our RM series encoders are qualified against all of the above — see our quality and testing page for details.
When to choose IP67 encoders
- Machine tools with coolant spray and chips
- Robot joints exposed to washdown or condensation
- Outdoor solar trackers and wind pitch drives
- Food, beverage and packaging lines with periodic cleaning
When you might need more (or less)
If your process uses high-pressure hot-water jets, ask about IP69K variants or protective shrouds. If the encoder is inside a sealed clean cabinet, a lower rating with better cost may be acceptable — but the temperature and EMI picture still matters.