×
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

Thermal distortion compinsation

Thermal distortion compinsation

Thermal distortion compinsation

(OP)
I have a mechanical instrument comprising a polycarbonate frame about 120mm and wheel 100mm dia mounted on miniature ball bearings.  I am running into difficulties with thermal distortion causing extra friction on bearings.  I am looking for design guides to minimise or compinsate for thermal distortion.
Any help would be apprecisted.

RE: Thermal distortion compinsation

What process method is this PC wheel manufactured?  If molded is it unfilled or filled? Molded PC shrinks linear .003 - .0075 in/in.  What is the operating temperature of this instrument?  Thermal expansion (CTE, linear 20°C) is 17.8 - 66.7 µin/in-°F.

Check http://www.matweb.com for you specific PC.

Heckler
Sr. Mechanical Engineer
SWx 2007 SP 3.0 & Pro/E 2001
XP Pro SP2.0 P4 3.6 GHz, 1GB RAM
NVIDIA Quadro FX 1400
      o
  _`\(,_
(_)/ (_)

(In reference to David Beckham) "He can't kick with his left foot, he can't tackle, he can't head the ball and he doesn't score many goals. Apart from that, he's all right."  -- George Best

RE: Thermal distortion compinsation

Conjecture:  The housing in in two halves, like a clamshell, with a bearing in each half.  The friction arises because the bearings become more misaligned with temperature.

Response if conjecture is correct:  Make one half just a cover, but both bearings in the other housing half, so their temperatures track each other and they are naturally aligned.  You will probably have to destroy the symmetry of the wheel, too, offsetting the web to clear the bearing housing.

Response if conjecture is not correct:  Tell us a little about the problem, already.



Mike Halloran
Pembroke Pines, FL, USA

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