Bucking of Rivets in Machined Parts

[Gerryy]

Hello,

Can anyone offer some insight into thier company policy regarding bucking rivets thru machined parts, in an airframe? Is it prohibited for concern of creating damage (micro-cracks) to the machinings ?

Appreciate any thoughts on this.

regards,
Gerry Y

 

[chuck1]

Hi Gerryy!
Solid rivets require high forces for installation which can, in some cases, damage rigid structure such as machined flanges. This is especially true for the vibration driving of titanium, A-286 and Monel solid rivets. The vibration driving of aluminum rivets require only moderate forces, but just to be safe, I usually prohibit vibration driving of all rivets in machined flanges and composites.
Hope this helps.
Chuck

 

[dnocarter]

What Chuck just wrote is very true. In my designs I always specify Hi-Lok type close tolerance bolts and collars when fastening machined parts in assemblies. Close tolerance bolts of this type are usually stronger than solid rivets.

Dean

 

[borjame]

Bucking solid rivets causes the rivet to swell inside the hole being riveted which in turn loads the hole in hoop tension. You need to be sure that there is a minimum thickness of material around the hole (minimum 2*rivet diameter from hole center to edge of part)so the part doesn't crack. If the hole location will be highly stressed, the pre-load needs to be factored into all calculations.

 

Boeing has been driving rivets into castings and forgings for 40 yr. that I know of. McDonnell used to prohibit vibratory riveting in titanium parts, on F15, and specified squeezed rivets. Cold worked, and interference fit Hilocks/hlts give some substantial hooping and pre- loads also, which is not always a bad thing.