|
Rivets and installation general notes
If you have access to both sides and are installing panels of dissimilar metals, use solid rivets if you can of the AN426-x-xAD and AN470-x-xAD when using 2024-t3 alloy. When using another alloy, select the rivets that match the strength of the alloy. Approx 1.5 the shank diameter should extend beyond the sheets prior to install. Use roughly 3x the thickness of the thickest sheet when selecting rivet diameter. This general rule is derive from the theory that the rivets will fail before the sheet fails. You will need specific data to calculate the bearing strength of a hole in vdifferent alloys and will need to adjust the general formula as required to match the alloy strength with the rivet strength to calculate for different alloys. but for AN470/426AD rivets 3x the thickness is a good starting point.
For example when riveting 2 sheets of .063 2024-t3 use a .187 or "-6" diameter rivet. The grip range is the two sheets and is .125. The rivet requires this length plus 1.5 x its own diameter for proper installation. therefore .125+1.5(.1875)=.406= rougly 6/16, so you would select An AN470-6-6 when riveting. The two head styles are AN470 universal and AN426 100 degree countersink. The AN470 series uses a different size rivet set for each size (-3,-4,-5,-6 etc measure in 32nds, length is measures in 16ths). So for driving an AN470-4 you would need a -4 or 1/8 universal rivet set and an appropriately weighted bucking bar. for 426 head rivets use a flush set.
As mentioned earlier you will need a (proper) rivet gun, not an air hammer. The rivet gun has the control and correct weight of piston to ensure the rivet is properly (not over) driven. The correct weight bucking bar also helps, I never really followed this rule except I knew when the bar would be too light. The size of the gun matters as well. They are measure in the "X" series, 2X, 3X,4X are the common sizes for anything up to 1/4.
For -3 and -4 use a 2x gun
For -3,-4,-5 use a 3x gun
For -5, -6, and -8 use a 4x gun.
I have all three if, you can get away with just a 3X for most of the work. Different manufacturers will have different weight pistons as well so one brand 3X will hit like a Standard 4x.
Get lots of practice driving rivets, going solid is the way to go for lightness, cheapness, strength and reliability. Sometime you have to go blind though.
There are many variations of blind rivets. In Aviation The most most common uses are Cherrymax, HuckMax, Allfast, ETC. Any rivet that is approved for direct solid rivet replacement by the manufacturer is whatever flies. If they want you to use Huck, thats what goes, any deviation then you need to call there engineering department to get approval for another vendors product.
The cherrymax superceeds the cherrylock, which superceeds the Cherry Friction lock, which superceeds the bulbed Cherry lock, All of which never really did as good of a job of the solid rivet, IMHO this is partly due to installers and repair people being lazy or not understanding the tolerances and limitations of blind rivets
The friction lock series retained its mandrel for added shear strength via friction. The Cherrylock , mechanically locks the rivet mandrel into place with a deformable locking collar which is pushed into place by shifting action by the tooling. The downside of this was that each rivet size and head style required its own nose piece along with a very expensive dual action puller. For a full set of heads and the tool, you looking at 5K. The cherrymax was introduced to reduce tooling cost and simplicity, i.e one size head pulls all diameters and head styles. There is also tooling avalaible that will allow you to pull a rivet behind a corner, or under something you would not be able to access normally. This tooling is also very $$$$
In the end I am using AN470 rivets were able, and cherry CR9163 series (friction lock) for there price advantage over the cherrymax series.
You do not have the required permissions to view the files attached to this post.
|
Login
Register
FAQ
Members
