In spite of all the advances in fastening methods, such as gluing and tightening, riveting is still one of the main method used by the aircraft assembly industry and also by other lightweight construction industries where the high strength sheet metal is not weldable.
September 10, 2019
There are several reasons for using the riveting method, among which the low cost of installation, the lower requirements for hole preparation, high reliability, light and strong joint due to the low weight, resistance to fatigue due to the high elasticity and durability.
A general rule is that the rivet should have a diameter of at least three times the thickness of the thickest sheet that is being joined. According to the military standard, so the bucked counter head diameter of the rivet joint must be larger than 1.4 times the diameter of the shank. The height must extend to 0.3 times the diameter of the shank. With all mentioned parameters, you can calculate the desired length of the rivet. The allowance is normally about 1.5D.
For example, two pieces of 0.050 inch (1.27 mm) sheet are to be riveted together. The proper diameter rivet would be 3 x 0.050=0.150 inch (3 x 1.27=3.81 mm).
A 5/32” rivet (0.156 inch, 3.96 mm) would be used. The metal thickness is 0.050+0.050=0.10 inch (1.27+1.27=2.54 mm), and 1.5D is 0.234 inch (5.94 mm), so the total length would have to be 0.10 + 0.234=0.334 inch (1.27+5.94=7.21 mm) for the rivet.
See image below:
In practical, for riveting such as overhaul and repair riveting, the general rule is to use the same size and head-style used in the adjacent structure. This will meet all the strength requirements for the joint.
Another topic related to the rivet is the hole preparation. After selecting the rivet size and placing the sheets, the holes must be marked for drilling.
These hole-marks should be punched with a center punch just deep enough to start the drilling.
If the punch is too hard, the mark will be too large and the metal will be distorted.
The drill diameter depends on the type of rivet in the hole:
Notice in the table that the drill size is about three thousands of an inch larger than the rivet.
After drilling, remove the burrs from the hole without chamfering the hole edge.
Sometimes the sheets can move or gap, in these cases you must use skin pins or clamps considering they will prevent the two holes from interfering and keep the sheets close together when it is time for riveting.
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