Views: 6 Author: Site Editor Publish Time: 2023-02-13 Origin: Site
Profiled linear guides,round shafts and ball screws are made primarily of steel components,they are highly susceptible to corrosives,which can quickly cause rust,pitting and degradation of critical bearing surfaces.
The simplest solution may be to consider bearings made of polymers.However,polymer bearings cannot provide the same load capacity,stiffness or running accuracy as steel bearings.When applications require high load capacity,high stiffness or high travel accuracy,steel components are the best technical solution.In these cases,designers and engineers can consider three factors to protect components from corrosion and ensure optimal bearing life.
Corrosion is caused by chemical attack on metals by hostile fluids or the atmosphere.
Probably the least expensive option a designer can use to prevent bearing corrosion is to mount components in a way that minimizes the entry of corrosive agents into critical surfaces.For most linear bearing components or systems,this means mounting them upside down or on their sides.Depending on the direction of the spray or splash,mounting components above the work area can also minimize the amount of exposure they have to corrosive fluids.However,if acid is the primary concern,vapors can be just as harmful as actual liquid contamination.In this case,it is best to mount the assembly below the work area since the vapors will usually rise.
Mount components in a way that minimizes the entry of corrosive agents into critical surfaces.
For linear systems enclosed in a housing,it is usually best to not use a cover if the system is installed upside down so that any liquid that enters the housing can be drained.When enclosed systems are installed upright,the addition of drain holes in the housing helps prevent liquids from entering the interior of the actuator.
Semiconductor wafer processing involves harsh chemicals such as hydrofluoric acid or potassium hydroxide.
When it comes to materials for corrosive environments,stainless steel is probably the first thing that comes to mind.However,because stainless steels cannot be hardened,they have a lower load carrying capacity than bearing steels and may not be suitable for that application.Even if stainless steel is acceptable from a performance standpoint,the range of linear bearing products in stainless steel or corrosion resistant steel is limited.If stainless steel is not an option,bearing steels(and aluminum)are available in a wide variety of plating and coatings to protect against virtually any corrosive agent.
●Lubrication and sealing
The most common cause of bearing failure is lack of lubrication,and while washdown processes(common in corrosive applications,especially in the food and beverage industry)remove contamination from components,they can also wash away lubrication.When linear bearing components or systems are used in washdown applications,grease is the lubricant of choice rather than oil because grease is less likely to be washed away.To further prevent bearing corrosion,full contact seals will help maintain lubrication inside the bearing and keep corrosive liquids out.
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