How IP Ratings Apply to Linear Actuators

If dust is more prevalent, rodless actuators may be further protected by adding a positive pressure port on the actuator body. This equalizes internal and external pressures and helps keep dust away from possible ingress points. In such factory environments, IP54 would be the minimum rating to consider as it would be protected from dust (5) and splashing water (4), even though splashing water may not be present.

In extremely dusty conditions where materials are being cut (such as in woodworking), or where there is light metal machining and grinding, dust accumulation tends to be considerably heavier. In these applications, a higher rating such as IP65 should be considered. It means the device is “dust-tight” (6) and protected from low-pressure (4.4 psi) jets of water. Even though water may not be present, the sealing mechanisms for keeping actuators dust-tight are typically effective against low-pressure water. Rod-type actuators with rod wipers or rod seals also perform well in these conditions. However, rodless actuators typically do not perform well unless some kind of custom-designed protection is applied. Custom-designed protection is best provided by the machinery manufacturer.

Liquid Environments

In applications with water present, it is important to fully understand the source, direction, and volume of the water the actuator will experience. For example, with an actuator carrying a reciprocating spray head directed away from the actuator and toward the processed product, some of the water, mist, or vapor will inevitably settle back on the actuator. It should therefore be protected against splashing water or low-pressure jets. The sealing mechanism of most rod-type actuators consists of a rod wiper or rod seal, so actuators with a rating of IP65 would be satisfactory. Rodless actuators will let some water in at some point unless custom-designed shields or guards are installed.

Some actuators, such as those that move products within the range of sprayed water, will be directly in the path of water. These devices should carry an IP66 or IP67 rating. Devices with these higher IP ratings will typically have redundant exclusion mechanisms such as shields, bellows, or guards, ensuring long-term operation. Again, rodless actuators will not perform well in these applications without customized protection.

Washdowns

Actuators are commonly found in food- and beverage-handling equipment that requires frequent washdowns. In such cases, actuator protection requirements are particularly stringent because the equipment is often cleaned with aggressive detergents, as well as washed and rinsed with hot (180°F), high-pressure (1,500 psi) water spray or steam. When specifying actuators for such applications, it’s important to understand the chemical makeup of the cleaning solutions. For example, the effects of very high or very low pH solutions on various components need to be fully understood so that sealing materials used are compatible with the detergents and pressures and do not degrade. This also requires that the metals used in the construction of the actuator body resist the particular cleaning solutions. Actuators with a rating of IP69K are best suited for this environment. However, it is always wise to perform testing on the solutions used in the process to ensure chemical compatibility.

Applications involving chemical solutions need to be treated somewhat differently than applications involving simple water ingress. IP ratings do not imply chemical compatibility. Knowing exactly what chemicals actuators will be exposed to helps the actuator supplier select materials most likely to offer good service life. Important factors to consider are the chemical makeup of the solution being used, its concentration level, duration of exposure to components to which it is applied, and operating temperatures.

Linear rod-type and rodless actuators are used in a wide variety of manufacturing applications that employ motion control in adverse environments that expose them to dust, liquids, and a variety of chemical solutions. Generally speaking, rod-type actuators are better suited to these types of conditions. Rodless devices can also be employed at ratings of IP54 or less. For higher levels of ingress protection, rodless actuators typically require some kind of external shields or enclosures.

When selecting linear actuators for applications that require protection against dust and liquid ingress, engineers should provide their supplier with as much information as possible about the dust and liquids the actuators will be exposed to so the supplier can ensure environmental compatibility, best performance, and long service life.

Gary Rosengren is the Director of Engineering at Tolomatic Inc.