What's the purpose of spot welding?

"TurboSloth" (TheTurboSloth) 02/15/2015 at 20:09 • Filed to: None

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I was looking over this story at speedhunters about Daigo Saito's garage, and I saw this chassis. What's the purpose of spot welding? Why not just make 1 continuous weld?

SaigaShooter - He's got an Impreza > TurboSloth 02/15/2015 at 20:15

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Maybe to keep the material from overheating and warping?

OPPOsaurus WRX > SaigaShooter - He's got an Impreza 02/15/2015 at 20:15

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exactly what I was thinking.

Arch Duke Maxyenko, Shit Talk Extraordinaire > TurboSloth 02/15/2015 at 20:24

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Making one continuous weld would warp the shit out of the metal and would be slower than automated spot welders.

DasWauto > TurboSloth 02/15/2015 at 20:27

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Weight, manufacturing time and expense. It's lighter (not too greatly, but appreciably), quicker and as a result, cheaper.

A seam welded shell is stronger but it's generally not worth doing on a production car. The EK9 Civic Type R is one example I know of that is.

desertdog5051 > TurboSloth 02/15/2015 at 20:29

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There are 2 different types of "spot welding". Each has its own value. Read this.]\

https://www.millerwelds.com/pdf/Resistance…

E. Julius > TurboSloth 02/15/2015 at 20:37

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All the reasons for spot welding that people have listed here are valid, however, this is changing as technology continues to develop. Techniques such as laser brazing and extremely precise robotics allow for cheaper and easier continuous seams, even on relatively pedestrian cars like the Chrysler 200

(source: http://www.chrysler.com/en/200/manufac… )

More info (a bit old though): http://aws.org/conferences/ab…

dogisbadob > TurboSloth 02/15/2015 at 20:46

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See spot run. See spot weld.

Or just use duct tape

PS9 > TurboSloth 02/15/2015 at 21:12

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This sounds like the perfect question for that Brown Welding Dog. Too bad he's busy doing a lap of America right now...

AMGtech - now with more recalls! > TurboSloth 02/16/2015 at 01:10

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What you see above is most commonly used in hot rod and restoration shops and is also known as stitch welding. This is done to prevent warping of the metal and it takes a long time and a ton of patience to do properly. It will often be a completely welded seam when it's finished.

Spot welding often refers to what is done on a production line or just for very small repairs. You may have seen spot welding on a vehicle's pinch weld. Two sheets of metal laying against one another with a spot welded every six inches or so. After it's been painted this spot will just look like a small 3/8" dimple. This is mostly used for speed and low cost.

You can tell a Finn but you can't tell him much > TurboSloth 02/16/2015 at 12:13

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Spot welding is easily automated, it is fast and it is repeatable. This makes it an excellent process for a high production environment. This video is a perfect illustration of the reason for spot welding.

If you watch a rally car build you see the reason that seam welding isn't used in a production environment. It does make a car stiffer, but at the cost of a lot of time from a skilled welder. That results in a car that is much more expensive than something that can get run down a line and spot welded. When they are looking at the engine bay you can see a lot of the spots where the body is seam welded. There is an offhand comment about it taking something like 500 man hours to weld the body and add the roll cage.