×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Ball bearing spin to roll ratio recommendation

Ball bearing spin to roll ratio recommendation

Ball bearing spin to roll ratio recommendation

(OP)
I am in the process of choosing hybrid ceramic ball bearings for a high speed alternator (turbo-generator) application and would like recommendations as to good spin to roll ratios. Various ball bearing design programs will predict the ball to spin ratio under specific loading and speed, but apart from a vague remark that lower is better there is no real discussion of the consequences.

For example if I have a 25 mm bore ABEC grade 7 bearing running at 56000 rpm I predict a ball to spin ratio of 0.36  This seems about the same as found in some Nasa publications but I need to know if this ball to spin ratio will cause a reduction in bearing life due to cage and or raceway/ball wear.

[Aside: I have failed to get support from the ball bearing suppliers in this -and other matters- because I am not at the point of being able to buy 100s of bearings. SKF will not even allow me to open an account and to pay for engineering support!].

Thanks for all constructive advice.


 

RE: Ball bearing spin to roll ratio recommendation

You might want to contact someone in the turbomachinery group at United Technologies/Pratt-Whitney/Rocketdyne in Canoga Park CA.

They have lots of experience in this area.  They make very high speed turbopumps.  They make the ones for the space shuttle fuel and lox pumps.  You need to also get the cages right.

At DN's this high (in your case 1.4 million), overall bearing life will be short.  Of course, proper lubrication, perhaps oil mist or something like that will be crucial for significant life.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources