Water, coolant spray and washdown fluid kill ordinary stepper motors — first the bearings, then the windings. A waterproof stepper motor solves this at the source with sealed construction instead of bolt-on covers. This guide explains what IP ratings mean on a motor datasheet, how sealing is actually engineered, which applications justify it, and how to choose between waterproof motors and IP65 integrated bus motors.

Reading IP ratings on motor datasheets

An IP code has two digits: solids then water. IP54 tolerates splashing from any direction; IP65 resists a 12.5 L/min low-pressure jet — enough for splash zones and humid rooms; IP66 survives powerful jets; IP67 handles temporary immersion (1 m, 30 min). For machine-mounted motors in washdown or outdoor service, IP65 is the practical baseline. Note the fine print: the rating applies to the motor body with properly glanded cable entries — an unsealed connector or a drilled junction box voids it instantly.

Rating	Test condition	Typical machine use
IP54	Dust-protected, splashing water	Dry cabinets near coolant mist
IP65	Jet water 12.5 L/min from any direction	Food splashes, outdoor gates, marine deck equipment
IP66	Powerful jet 100 L/min	Direct hose-down zones
IP67	Immersion 1 m / 30 min	Floodable pits, submersible frames

How waterproofing is engineered

A waterproof stepper motor is not a standard motor with a boot pulled over it. Manufacturers change three things: front bearings become sealed types with contact seals against the shaft; the flange and housing get O-ring gaskets at every joint and a gasketed rear cover instead of snap rings; windings receive vacuum resin potting so that even condensation inside the shell cannot reach copper. Output shafts commonly switch to stainless steel, and the cable exits as a sealed molded gland or IP-rated connector. The electrical design — 1.8° hybrid stepper construction, current ratings, torque frames — stays standard, so sizing carries over directly.

Applications that justify the premium

The classic users: outdoor access and gates (barriers, bollards, camera pan drives), marine and dock equipment, food and beverage conveying with daily washdown, agricultural automation (irrigation, feeding lines) and medical/lab devices that are wiped with aggressive disinfectant. A reliable rule: if the maintenance plan already includes “replace motors yearly”, sealed motors are cheaper than the replacement schedule. In 42/57/60 frame sizes (NEMA 17/23/24), sealed open-loop motors cover most of these duties; when the same axis also needs coordinated motion, an IP65 integrated closed-loop bus motor removes both the cabinet and the protection problem in one part.

Selection checklist

Five checks before ordering: (1) match frame size and torque exactly as with standard motors — sealing does not change the torque-speed curve; (2) confirm the rating covers the connector, not only the body; (3) specify cable length and gland type at order time, since sealed cables are not field-spliceable; (4) for washdown chemicals, check the shaft and flange material — stainless shafts are standard; (5) decide open loop vs closed loop — in wet areas, closed loop’s stall alarm often prevents the cascade failure of a machine continuing to run with a seized axis.

FAQ

Q: Can I make a standard motor waterproof by covering it?
A: Covers help with splashes but trap condensation and usually fail at the shaft exit, where water pressure is highest. Sealed motors integrate the protection where it matters — bearing seals and potted windings.

Q: Do waterproof steppers derate torque?
A: The motor performs like its standard equivalent. Derating comes only from thermal management: sealed motors dissipate slightly slower, so avoid mounting them inside insulated enclosures.

Q: IP65 or IP67 for my machine?
A: IP65 for jets and heavy splash (most machines); IP67 only where immersion is credible — floodable pits, equipment hosed into standing water. Above that, look at purpose-built submersible actuators.

Summary

Match the IP rating to the real water exposure, keep motor sizing unchanged, and buy the sealing as part of the motor rather than as accessories. Compare waterproof open-loop stepper motors (IP65) in 42/57/60 frames, or step up to IP65 integrated EtherCAT closed-loop motors when the axis needs networked motion in the same wet environment.