Ask an EngineerStainless steel linear actuators stand up to corrosion, tough conditions
By Tolomatic on April 3, 2018
Machine designers who develop systems for harsh environments often need corrosion resistant components, including stainless steel linear actuators, to stand up to challenging environmental conditions.
Corrosive agents, moisture and dust in manufacturing environments impact the performance and life of components like electric linear actuators. Dust and debris may enter housings causing moving components to wear. Moisture may short electrical connections. Corrosive agents can eat away at housings, seals, fasteners and more.
For confirmation that a component will stand up to environmental factors, we recommend the IP (International Protection or Ingress Protection) rating system. Developed by the IEC (International Electrical Commission), it classifies the degree of protection against given hazards a component provides.
Learn about the IP rating system. Download our white paper.
Why stainless steel
When a machine is designed for a corrosive environment, stainless steel is often the material of choice? Why? It’s because of stainless steel’s resistance to corrosion.
Stainless steel is an alloy with a minimum of 10.5% chromium. It’s corrosion resistance increases with more chromium. The addition of molybdenum increases resistance to corrosion from acids and pitting from chloride solutions. There are numerous grades of stainless steel with varying chromium and molybdenum content. (Types 304 and 316 are most common in linear actuators.)
Unlike carbon steel, stainless steels do not suffer uniform corrosion when exposed to moisture. They contain sufficient chromium to spontaneously form a microscopically thin, inert film of chromium oxide. This prevents further corrosion by blocking oxygen from getting to the steel surface.
However, stainless steels may corrode when exposed to some acidic and basic solutions. The possibility of corrosion depends on the kind of acid or base, its concentration and the temperature of the solution. A machine designer can avoid this type of uniform corrosion by consulting published corrosion data and selecting materials accordingly.
Stainless steel’s resistance to corrosion makes it an ideal material for many industrial applications, including equipment in paper mills, chemical plants, water treatment facilities, and food processing operations.
IP ratings and linear actuators
Dust
There’s dust in most manufacturing plants. If conditions are extremely dusty (as in woodworking, machining, or grinding), linear actuators need an IP6__ rating (dust tight).
Water
The protection rating should match the level of the problem. If the linear actuator will be directly in the path of spraying water, immersed or subject to high pressure, designers need linear actuators with IP__6, IP__7 or IP__9K protection (water tight).
Corrosion
While there is no IP rating for corrosion resistance, many manufacturing environments have corrosive agents present. We recommend the designer begin with the IP67 rating or IP69K, and then refer to a published resource on corrosion resistance for information on specific metals and corrosive agents.
Stainless steel linear actuators
When it comes to linear actuators, the housing, fasteners, rod, gasket and seals need to have the required corrosion resistance in order for the actuator to withstand the environment. That usually means stainless steel housings, fasteners and rods. We offer a variety of IP67 and IP69K stainless steel linear actuators that meet the needs of many industries.
ERD electric rod actuators
ERD electric cylinders are the perfect alternative to pneumatic cylinders for automating manual processes. Used for gating, sorting, diverting and product changeovers, the ERD offers both IP67 and IP69K options.
ERD stainless steel electric actuators (SS2) are IP69K rated and are washdown ready. They feature an integrated motor in a protective enclosure that accommodates either servo (23-frame) or stepper (NEMA 17 and NEMA 23-frame) motors. 
ERD hygienic electric actuators are rated IP69K and approved by 3A and USDA for food and beverage applications. Our hygienically designed, all stainless steel electric actuators deliver up to 7868 lbf (35 kN). They are an excellent solution for food and beverage applications where higher forces are required for pressing, pumping, cutting or slicing.
Download our catalog for ERD electric cylinders.
ServoChoke® SVC electric choke valve actuator/operator
ServoChoke® SVC is a high performance linear integrated electric choke valve actuator that meets the rigorous needs of the oil and gas industry. The SVC provides more reliable, high-speed, precise electric choke operator performance than conventional hydraulics or jack screw assemblies. The ServoChoke SVC is designed for Managed Pressure Drilling (MPD), set-point choke control and Choke & Kill for well control applications.
Integrated servo linear actuator
We have designed many stainless steel actuators for specific applications, like this round body, integrated servo linear actuator used in volumetric filling. It combines features of our ERD and IMA actuators into a compact, IP69K design that provides seamless integration with Rockwell Automation Kinetix 5500/5700 servo drives.
Custom products
If our standard products don’t meet your needs, consult with our engineers about developing a custom solution.
Resources
Learn more about IP ratings and linear actuators in our white paper, IP ratings and the manufacturing environment: How to apply linear actuators for quality, safety and long service life.
Interested in electric linear motion? Join the discussion at our LinkedIn group.