What you need to know about corrosion-resistant linear guideways？

Recirculating ball and roller guides are the backbone of many automated processes and machines,thanks to their high operating accuracy,good rigidity,and excellent load capacity-a property achieved through the use of high-strength AISI/ASTM 52100 chrome steel(commonly referred to as bearing steel)as load-bearing components.However,since bearing steel is not corrosion resistant,standard recirculating linear guides are not suitable for most applications involving liquid,high humidity or significant temperature fluctuations.

 ALM super quality cost-effective corrosion resistance linear guideway 

To meet the demand for recirculating guides and bearings that can be used in wet,humid or corrosive environments,manufacturers offer corrosion-resistant versions.But the level of corrosion resistance provided by linear guides or bearings will vary,depending on the materials and processes used in their manufacture.

Since there is no standard or industry-accepted definition of corrosion resistance,we have summarized the most common corrosion resistance grades and their main uses provided by manufacturers of recirculating linear guides and bearings.

●External metal parts made of corrosion-resistant steel

The first line of defense against corrosion is to address the components of the bearing system that will be exposed to the environment,namely,the bearing housing and the guide rail.These parts can be made of martensitic stainless steel(400 series).Martensitic stainless steels are ideal for bearing applications because they can be treated with dimensional stability and hardened to withstand the extreme pressures and Hertz stresses inherent in recirculating linear bearings,especially those using ball bearings on rolling elements.

Some manufacturers offer linear guides made of austenitic stainless steel(300 series),which have better corrosion resistance than martensitic stainless steel.However,austenitic stainless steel does not harden sufficiently and has a lower speed and load capacity,making it less suitable for load-bearing surfaces than martensitic stainless steel.

●All metal parts made of corrosion-resistant steel 

For applications where exposure to salt water,acid,alkaline solutions(bases)or steam may require the use of stainless steel for all metal components(inside and outside of the housing).Because they carry loads,the balls or rollers are usually made of martensitic stainless steel(as are the bearing housings),while non-load-bearing parts(such as fasteners,end plates,and lubricating parts)are made of austenitic stainless steel.In this configuration,it is important to note that the load-bearing parts(especially raceways and rollers)are made of stainless steel rather than bearing steel,so the bearing capacity is reduced.

●External metal parts chrome plated

For the highest level of protection against corrosion,all exposed metal surfaces can be plated-usually hard chrome or black chrome.Some manufacturers also offer a black chrome coating with a fluoroplastic(Teflon or PTFE type)coating to provide better protection against corrosion.Chrome plating can be applied to most metals,including stainless steel.The disadvantage of plated linear bearings or rails is that it increases the thickness of the plating surface,so it changes the height and width tolerances of the bearing assembly.

●Other options for corrosion resistance

In addition to stainless steel and chrome for linear guides and bearings,there are other options that allow designers and users to address corrosive environments.One is to use a recirculating linear bearing with an aluminum bearing seat(main body).This design may be sufficient for unlikely applications where wet or corrosive conditions are met,or where components are not directly exposed to caustic agents.Aluminum bearings are lighter in weight and often cost less than other corrosion resistance options, but they typically offer only a fraction of the size,preload and accuracy classes,and their static load capacity is lower than steel or stainless steel versions.

Two other corrosion resistance options for linear guides(especially for applications requiring FDA or USDA compliance *)are electroless nickel plating and nickel-cobalt plating.In addition to meeting the standards set by the USDA and FDA,both coatings have excellent corrosion resistance and hardness and are available on steel and stainless steel components.

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