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Bushing Press Fit Force
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Posted by: CaptnPea ®

07/22/2005, 09:59:45

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Hey All,

I'm trying to dig up information on the calculation of force required press fitting a bronze bushing into a piece of sheet metal. I have located information on hoop stresses for pressing a shaft into a hole or boss in plastic, but, my case is a little different in that I do not have a solid section being pressed in, along with the difference in modulus (steel 30.6E6 vs Bronze 15E6 psi).

Basic sizes I'm working with...

Hole: .500"
Max dia interference: -.003"
Bushing Wall: .125" (ID of .375")

The tricky part is that the dissimilar modulus of the materials is making things a bit more complex than just calculation of the hoop stress in the bushing then applying Hooke’s law to back solve for a pressure to force the circumference change required to get into the hole.

Anyone have a source that has resolved governing equations for this situation?

Oh.. and in sliding it in, anyone have an opinion on what would be a reasonable range of mu (friction coef.) would be?

Thanks,
Captn







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Re: Bushing Press Fit Force Smile
Re: Bushing Press Fit Force -- CaptnPea Post Reply Top of thread Forum
Posted by: Gary Kemp ®

07/30/2005, 18:59:15

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I would press some in and measure the actual force required. If this is for an automated system you will want to provide an excess amount of force to ensure the installation anyway. I think you can spend hours calculating and you would still get no closer than testing would provide. Particularly when you consider all of the variables involved. Tolerances, surface finish, lead in edge condition, lubrication, initial part alignment, etc.






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Re: Bushing Press Fit Force
Re: Re: Bushing Press Fit Force -- Gary Kemp Post Reply Top of thread Forum
Posted by: trio ®

08/24/2005, 22:30:12

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I would also like to know how to calculate this scenario. Physical testing is a good shortcut but I cannot measure something that wasn't mfg'd yet. I need an example to help me understand the problem.

I have read the following link, but I do not understand yet how to get "pressure factor".

/manufacturing_spec/press_fit_force.htm

The materials that I would be using would be 440c passivated pin Rc 50-58 0.2501-.2503 dia. x 1/2" long & Titanium 6Al-6V-2Sn thru bore at 0.2498-0.2500, 1/2" thick mat'l. Titanium will be anodized for color. Pin will be flush once installed. No lubrication permitted.

Two questions:
1. What is the initial force to start engagement?
2. What is the force once started?

Please point me in the right direction.







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Re: Bushing Press Fit Force Smile
Re: Re: Bushing Press Fit Force -- trio Post Reply Top of thread Forum
Posted by: Gary Kemp ®

08/25/2005, 06:27:32

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http://www.engineerstoolbox.com/doc/etb/mod/stat1/interference/interference_help.html

I would start here. Once you determine the torque value that would be transmitted by your application you can convert it to linear force. It looks like the force factor you refer to isn't listed for diameters less than 1 inch.







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