What makes linear guideway suitable for high temperature use?

For most recirculating ball and roller linear guides,the permissible operating temperature range is -10°to 80°C,with some configurations rated for temperatures up to 100°C for short periods.But not all applications are in this temperature range,each component in the linear bearing assembly(bearing seat,guide rail,ball,seal,etc.)has a different maximum and minimum operating temperature.However,if you choose the right metal parts,plastic parts,lubricants,and optional accessories,you can configure a recirculating linear guide that can withstand high(or low)applications outside the standard -10° to 80°C range.

Metal components

The metal parts of the recirculating linear guide include bearing housing,recirculating ball or roller,guide rail,scraper and various fastening and mounting screws.The components can include three or more different types of steel,stainless steel,and in some cases aluminum.Therefore,it is important to know what type of metal each component is made of and the temperature range it can withstand.

In many cases,manufacturers recommend using stainless steel whenever possible when the application is outside the normal operating temperature range,especially when the temperature is very high(above 150°C)or very low(below 0°C).One of the reasons for this recommendation is the possibility of temperature fluctuations,which can cause condensation and lead to corrosion.

Linear bearings and guides are composed of a variety of different materials,each with a specific acceptable operating temperature range.

Plastic components

Plastic parts,such as seals and recirculation parts,are usually the limiting factor for the temperature suitability of recirculated linear bearings.However,linear guide manufacturers offer seals made of special materials,such as FPM or FKM(DuPont's fluorinated rubber,commonly called Viton),with an extended operating temperature range.

If the environment is free of liquid or solid contamination,another option is to use linear guides with metal seals only.While it is not recommended that profiled linear guides completely abandon seals(as they help maintain lubrication inside the bearing),circular shaft linear guides and CAM roller sliders can operate without seals,making them an alternative for applications that do not require the load capacity or stiffness of profiled linear guides.Since these designs do not require plastic recirculation components,they are available in all-metal versions that can withstand temperatures outside the range of most plastics.

Seals help maintain lubrication inside the bearing,but special sealing materials may be required in extremely high or low temperature environments. 

Lubrication

Temperature will also affect the lubrication performance of the circular linear guide.Specifically,the temperature of a lubricant affects its viscosity(flow resistance),and grease lubrication exceeding its rated temperature separates into its components(base oils,thickeners,and additives),thus reducing its effectiveness.

In general,lubricants with lower viscosity are recommended for low temperature applications,while high viscosity lubricants are best for high temperature applications.Keep in mind that in addition to the type of lubrication to be used,the recommended lubrication interval is also affected by the operating temperature of the bearing.

Optional components and accessories

Temperature restrictions also apply to optional components such as additional seals,external lubrication,and cover strips or bellows.For example,circular linear guides are typically rated for use at temperatures up to 80° C,but external lubrication units are typically rated for maximum temperatures of 50° to 60°C.Sensitive components,such as measuring systems(integrated linear encoders)and integral parts of recirculation systems,such as ball chains or ball separators,should also be checked to ensure that they can withstand high or low operating temperatures.

Ball chains(aka ball cages)directly provide continuous lubrication to each ball,but they are made of plastic and may reduce the allowable operating temperature of linear bearings.