Why are airplanes made with rivets, instead of welding?

Answer 1

Some parts have always been welded. Where the strength isn't needed rivets, and other fasteners, are cheaper and faster. Modern commercial aircraft are more often glued together, I tested some adhesives that were stronger than the alloys they were connecting back in the 1980s and I'm sure they have improved since.

calnickel: Even though you are right about the friction stir welding, what's less capable about housewives? Are you implying that women who choose to stay home, which was virtually the only choice available in 1942, are somehow stupid? I know a good number of female engineers who'd probably like to make your life difficult for a comment like that.

Answer 2

Airplanes were being assembled with welds until the 707, which had spot welds for attaching fuselage stringers. However, the weldments created fatigue hot spots that resulted in early cracking; so rivets- which cost more- were substituted back in.

Friction stir welding is beginning to be used where fatigue is less critical (rockets, light planes) although it is not technically a weld, since the material is not melted- it is deformed plastically by mechanical stress instead of thermal stress, and therefore disrupts the heat treat of the surrounding material less than welding. Also, laser welding is under development (Airbus has some test panels flying).

Answer 3

Airplane Rivets

Answer 4

In the event of damage, the safety of drilling out a rivet, with regard to surrounding structure, is faster and poses less heat tempering than going after a weld with die grinder and an abrasive wheel.

Welding is a skill, and it's not one that all of us possess. If you look at the work of a skilled welder, it's almost a thing of beauty; if you look at my welds, you'd think that they were done by my dog, after a bowlful of beer, and armed with nothing more than a car battery, jumper cables and a nickel.

The standard test for welding is the "drop test:" If you drop it, and it breaks, you need to re-weld it. This probably is not a good practice for airframe maintenance.

Rivets, even flush rivets, announce their imminent failure by "smokng" which indicates that they need to be replaced while welds just break when they're ready to let go. You can look at an aircraft freshly flown after a wash and determine the amount of sheet metal work it requires by the number of working rivets that leave a trail of corrosion on the skin. A failing weld doesn't tell you when it's about to snap.

Also, you have another aesthetical issue in the appearance of an aircraft. The cost of repainting an aircraft is enormous. If we routinely re-welded, and then repainted, components, the plane would look like it had a pox. I can replace a rivet and dab some touch up paint on it, and the entire airframe won't look like it's healing from an the aviation equivalent of road rash.

There are also flammability issues. The fuel tanks of most aircraft are in the wings, which short of rope and dope planes, are riveted. Jet's usually feature a "wet wing" in which case the there isn't a bladder, isn't an actual tank, and the wing itself serves as the tank. I'm not eager to go welding on something I think could blow up in my face.

Avgas is much more volatile than Jet A, or Jet A-1, and usually feature actual tanks. They're also vented. Even the few wet wing designs are vented. I have absolutely no relish for the idea of welding on an airframe that's likely to land me and my eyebrows in seperate counties whether I'm doing the welding or just standing too close to the person doing the welding, sitting in my office for instance.

Being blown up is never any fun. Being treated for burns is never any fun. Climbing into the tail of a C-172 to buck rivets isn't fun either, but it beats trying to figure out how my clothing caught fire while I was sitting at my desk any day, hands down.

Some parts are welded. And the recommendation by my A&P instructors was to take them to a welding shop, inform them where the part came from and the magnitude of a weld's failure, and then watch as it was welded. It doesn't hurt to get a copy of the company's liability insurance binder for your records, and inspect the weld personally before priming and painting it to prevent corrosion.

In short, welding is a good way to make the flying public afraid to get on an aircraft, as well as turn a hangar into a mushroom cloud. Rivets, on the other hand, allow for convenient visual inspection, can be replaced without repainting, and can be conveniently replaced if suspect without having to x-ray the airframe. If you've never x-rayed an airplane, let me assure you that it almost makes driving a few counties away to figure out where my eyebrows came down seem like fun.

Fly the Friendly Skies!
JT

Answer 5

Welding is heavier. Skin panels sometimes must be removed for repairs and rivets are better to remove/ replace than welded joints.

Rivets can be uniformly strong while welding is unpredictable and completely dependent on the skill of the welder.

Rivets are cheaper than welding.

Answer 6

The heat treatment of the aluminum panels would be adversely effected requiring the entire plane to go back into treatment after the welding, not very feasible.
Another reason may be based somewhat on the high cost of clearing the assembly area to X-ray inspect the welds which would be required if welded.

Answer 7

Airplanes need more flexablitiy than welding will allow. This is because of the forces and movement in flight. Also many parts of the aircraft are under the skin of the aircraft and rivets and screws provide for easier access than welding would.

Answer 8

New aircraft (like the Eclipse VLJ) are being made using friction stir welding.

Traditionally, riveting has been easier to do since heat treating is unnecessary (airplanes are made of heat-sensitive aluminum, not steel), quality control is easier, and training much much easier (they taught housewives how to rivet in WWII).

Chris H, take it easy. I was implying that people who weren't mechanically inclined could (and did) build thousands of aircraft for the war effort and deserve as much credit for winning the war as the pilots flying. I've worked with (and learned a lot from) many female engineers and pilots and I have the utmost respect for them.

Answer 9

Rivets provide more flexibility to the structure. Also it is easier to make repairs to a riveted structure, you can take out the rivets and replace panels without cutting the structure.

Answer 10

http://www.nps.navy.mil/avsafety/gouge/stress.htm