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Thermal Expansion to Retain a Bolt

  1. Jan 10, 2018 #1
    I have 1" aluminum rod and I want to dril a hole in a steel structure for the bolt.

    If I have a 1" drill and take .001" inches off of it at the machine shop, so that it is now 0.998 inches, there will have to be about a 200°C difference in temperature between the two articles (aluminum having a coefficeint of expansion of 17 x 10-6 and steel 11 x 10-6) which shouldn´t be a problem.

    There will be some mechanical retention (a bolt passing though both structures), but I was wondering if I am able to slide them together before they cool off and/or heat up how secure would this retention be withiut the mechanical retention (say it´s just one inch of length where they meet).
     
  2. jcsd
  3. Jan 10, 2018 #2
    I show aluminum at 0.000023 - so you would need to cool it to about 120C.

    https://www.engineeringtoolbox.com/linear-thermal-expansion-d_1379.html

    It would be a very firm connection. Since restoring that thermal difference would be nearly impossible once the metals were in contact, it would be permanent.
    Of course, slide them together smoothly. Once they bind, that's it.
     
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