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    Discussion in 'Calculations' started by Weseda, Mar 12, 2015.

    1. Weseda

      Weseda New Member

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      Hi all, I'm new here and I have a pretty basic question.

      I'm designing a press-fit assembly, and need to find out the specific geometric requirements to ensure a high enough pull-out resistance. I'm pressing a thin-walled (0.4mm) cylindrical metal part over a cylindrical plastic part. The diameters are about 20mm. Are there approximate methods I can use to get pull-out force values for a given amount of interference? Going one step further, is there a way to calculate pull-out force if the plastic part has crush ribs?
       
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    3. Lochnagar

      Lochnagar Well-Known Member

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      Hi Weswda,

      If you download this Excel spreadsheet - you will be able to calculate the force required to push the two parts together - see the values in red text on the bottom left of the spreadsheet. The big unknown/variable is the chosen value of the coefficient of friction - see the top left of the spreadsheet.
      As for your second option of "crushed ribs" - well the only way you will be able to quantify that is with FEA and/or experiment with the parts.

      http://web.mit.edu/2.75/fundamental...ssion Spreadsheets/Joint_interference_fit.xls

      Hope this helps.
       

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