FEATURE LINEAR MOTION


HOW TO COMBAT CORROSION IN H If left unchecked, corrosion in actuators will


impact performance, functionality, durability and safety, as well as increase maintenance costs, sap energy, and impact the environment. To


overcome the problem, actuator designers are increasingly making corrosion-resistant products using advanced materials, improved sealing strategies, and with the ability to withstand extreme temperatures. This new generation of


actuators requires minimal maintenance and can act as high-function replacements for pneumatic and hydraulic cylinders in corrosive environments, as Anders Karlsson, senior product manager – Linear Actuators at Thomson, explains


E


xtended exposure to moisture and humidity is the primary cause of corrosion in actuators. The in-out motion of the actuator


shaft creates a negative internal pressure, which may require some kind of pressure relief function to prevent ingestion of moisture. The reaction to the metal surfaces and the water, facilitated by oxygen in the air, corrodes the metal. If the actuator is going to be used in marine


or coastal environments, it will be even more susceptible to corrosion because the salt interacts with the metals. In addition, corrosion can also be exacerbated by extreme hot or cold temperatures, particularly where


high condensation or rapid temperature changes are present. Operating in hot environments adds wear to all components and challenges lubrication. Another factor is exposure to aggressive


chemicals. Opening and closing valves in sewage treatment plants, dispensing fertiliser or applying pesticides, are among the many actuator applications that can corrode motion control equipment that is not adequately protected. Lastly, interaction with other environmental


factors can deepen corrosion. Running diesel- fuelled engines in humid, coastal regions, for example, not only adds greenhouse gases to


the atmosphere but contributes to corrosion, especially in unfiltered maritime applications.


PREVENTING CORROSION Controlling corrosion is a function of the primary material, coating, sealing, temperature control and adequate maintenance. To prevent corrosion in actuators it is important to: select materials suited to the operating environment, implement proper maintenance and inspection routines, and consider protective measures such as coatings, seals, or enclosures to shield the actuator from environmental factors.


Materials and coatings Stainless steel has excellent corrosion resistance, making it the primary choice for applications where exposure to moisture, chemicals or other corrosive substances is a concern. It is an especially good choice where there is a risk of scratching or mechanical wear, as in actuator fixations, for example. Anodised aluminium is a lighter and less


Thomson electric actuator ratings for IP67 (static), IP69K (static) and IP66 (static/dynamic) resist corrosion from salt water, UV radiation, washdowns, etc.


36 DESIGN SOLUTIONS FEBRUARY 2025


expensive alternative to stainless steel. It is significantly harder with more wear and scratch resistance than untreated aluminium. Its dense, self-healing aluminium oxide layer resists wear and scratching, protecting the underlying aluminium from corrosion and oxidation. Anodised aluminium is, however, less corrosion resistant than stainless steel and not recommended for the harshest or most corrosive environments. Despite this, it does have better thermal conductivity than stainless steel, making it worthy of evaluation for intended high-temperature operations. Nickel plating offers some corrosion resistance but is prone to scratching. Some actuator vendors also use corrosion-resistant plastics –


The Thomson Max Jac corrosion-resistant rugged linear actuator uses advanced material, sealing and temperature tolerance to operate in harsh environments without maintenance for 500,000 cycles


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