Recommended chamfer dimensions
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Posted by: bilbat ® 10/01/2003, 15:04:29 Author Profile eMail author Edit

I have a stainless steel bushing (1/4" diameter) being pressed into an aluminium bore. At times the bushing becomes misaligned and a burr is "rolled" at the leading edge of the bore. What should the dimensions of the leading chamfers (bore and shaft) be to maximize alignment/minimize burr? Physics and experience tells me the steeper the better but I can not find supporting documentation (so site references please!). Thanks. I have seen the evils of procrastination and plan to change my ways tomorrow! Bill

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press fit chamfers
Re: Recommended chamfer dimensions -- bilbat	Post Reply	Top of thread	Forum

Posted by: RKimball ® 10/01/2003, 22:46:15 Author Profile eMail author Edit

Hello, First if you are pressing stainless into aluminum I'd recommend that you have a short slip fit length before the press fit size on the bushing. As important as the chamfer size is the fact that the chamfer does not have a sharp transaction area. If you choose not to have a slip fit lead in, then you need to break or polish the edge of the chamfer. Chamfer cuts often kick up a sharp micro lip at the corner, and stainless will have no problem using this kick up as a hole reamer. Second, be sure to consider the difference in heat expansion before you choose your two press fit diameters. Aluminum expands more than stainless and you could have a loose bushing at some temps. If you are pressing the stainless bushings into a thin aluminum area you may warm the aluminum to make it accept the bushing easier or chill the bushing. .. or both.. If the aluminum is a larger cross sectioned casting or billet, warming sometimes has the reverse effect, depending on the cross section shape. To answer the actual question... any chamfer that is larger than the hole is going to work... it is the sharpness of the transaction that is the effect. ... or problem. ..... but I'd use a lead in registor dia. to allow for a straight well centered start as I first stated. G'luck -randy- ** The worst suggestion of your lifetime may be the catalyst to the grandest idea of the century, don't fail to listen to suggestions. -randy-

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Re: press fit chamfers
Re: press fit chamfers -- RKimball	Post Reply	Top of thread	Forum

Posted by: CHSH ® 08/02/2007, 15:13:48 Author Profile eMail author Edit

We have experieced the following: SS Bush OD 0.7765+/-0.0005 and Aluminum bore 0.7750+/-0.0005 with 0.050 X 15 degree chamfer on the leading edge of SS bush. We applied lubricant on the OD of SS bush during pressing bush into aluminum bore. This application works 100%. CHSH

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