"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.
Jian Chen is the General Manager of Shanghai Luoyun Intelligent Technology Co., Ltd., with direct responsibility for the RM series encoder program and customer engineering support.