Very High Temperature Bearing? 2

[acspain]

Good Afternoon,

We need help in selecting an appropriate bearing technology for an application. We don't have a complete specification yet and can design around the bearing choice.

The basic criteria is 900 F temperature, 3 rpm max, 100-200 revolution life over course of 5 years.
Output bearings, 1 inch shaft, combined axial and moment load could be as high as 1000 lbs.

Research on the web is pointing us to ceramic but that is presenting issues with mounting on stainless steel shafts and in stainless steel bores from a coefficient of thermal expansion viewpoint.

Thank you for your help.

 

[dvd]

Axial load is pounds, moment load is lb-in - inconsistent units. Depending on geometry, your 1" diameter shaft seems small.

Call and talk to an applications engineer at Graphalloy -

https://graphalloy.com/

Young's modulus for stainless steel (which alloy?) at elevated temperatures
(

https://nickelinstitute.org/media/4657/ni_aisi_9004_hightemperaturecharacteristics.pdf)

 

[TugboatEng]

Second for Graphalloy. Consider housing the bearing in an Invar alloy if you need to control thermal expansion.

 

[Jessica Walliams]

SKF high temperature bearings are designed for challenging operating conditions, with variants capable of performing at temperatures as high as 350 °C (660 °F). These bearings incorporate graphite-based lubrication which can lubricate at high temperatures and low speeds, eliminating the risk of metal-to-metal contact.

 

[3DDave]

Another post plagiarized, this time from

https://www.skf.com/binaries/pub12/...rature-bearing---14961_3-EN_tcm_12-271804.pdf

"SKF high temperature bearings" brochure.

It's also not useful as the bearings that brochure covers are "For operating temperatures up to 350 °C (660 °F)" or quite a bit short of the 900°F required.

 

[acspain]

Thank you to all for your posts.

Graphalloy is definitely a possibility for the application.

Does anyone have experience with tolerancing rings to deal with the difference in thermal expansion between ceramic and stainless steels?

Have a good day!

 

[TugboatEng]

Sorry for the plagiarism, Dave . However, from the FAQ page at the Graphalloy website:

Q. GRAPHALLOY bearings can be pressed in with much greater press fits than hard carbon materials; how does this help?

A. Generally, the harder the carbon material, the HIGHER its elastic modulus (stiffness). GRAPHALLOY has a LOWER elastic modulus and therefore tolerates greater press fits. Being more flexible allows GRAPHALLOY to better withstand the shock of shop handling, pump installation and most importantly, pump operation. Hard carbon bushings chip more easily when dropped and are at a disadvantage when encountering similar shocks in use. Since hard carbon materials cannot tolerate heavy fits, they are difficult or impossible to use for high-temperature applications - they can become loose as their housing bore expands in the heat.

 

[3DDave]

Not you Tug - I was referring to Jessica who has spammed nonsense over many forums.

 

[TugboatEng]

All good, just making a joke as I was about to copy and paste a post.