The first thing to consider for elevated temperatures is that you have the correct grease. Standard greases will begin to liquify in applications above 130°F, requiring more frequent re-greasing. We recommend choosing a lubricant with a maximum temperature rating of at least 50° above the hottest temperatures in your application. This applies to the grease used in the wheel bearings and the grease used in the swivel section bearings. Many commercial ones are available that are good for temperatures up to 450°F.
For high temperature casters, the next component to consider is the tire material. The hotter the application, the harder the wheel needs to be. Using plastics for applications above 300°F is not the best choice; typically, steel or another metal wheel are the better options.
Keep in mind that using a metal wheel will withstand the higher temperatures but causes increased wear on your floor. Below 300°F, there is typically a plastic, rubber, or urethane wheel that can withstand elevated temperatures for short periods.
After selecting the wheel material, it’s time to discuss wheel bearings. As parts heat up, they expand, so for applications above 250°F special clearance bearings are needed. Sometimes these can be obtained in ball bearings or tapered roller bearings. Usually, a standard caster roller bearing is used in applications above 300°F because the clearances allow for thermal expansion. The downside to the caster roller bearings is they are good for manually moved or straight line applications. If towing a cart or dolly through a facility, use tapered or ball bearings and make sure clearances are properly specified.
Next, we would look at the caster swivel section: Here, maintenance-free swivels would only be good up to 150°F since the grease would begin to melt out, and you can’t regrease. We typically recommend kingpinless styles since they have the most internal clearances and can easily be regreased with high-temperature grease. Kingpin style swivel sections with ball bearings will work up to 250°F as the tapered roller bearing secondary bearing may lock up at higher temperatures.
Finally, for extreme temperatures over 600°F, you need specialized grease. You also have to consider the strength of the materials used. Steel will begin to lose strength above 600°F and is at approximately 50% strength at 1100°F. We see these applications typically in heat treat furnace applications.