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?

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.