Welding Tips and Tricks

I'm putting this in the general forum as it's common for most types of welding.

In general the power flows from negative to positive, except in the case of AC where it alternates.

My question is why does it make so much noise when the power flows in both directions? This is true with all forms of welding, AFAIK.

To be honest, I'd like to have AC so I can weld aluminum but the noise is not something I'm looking forward to. In fact I would go so far as to say that one of the reasons I like DC Tig is that it's so quiet.

So what gives with AC and why is it so noisy?

You could wear ear plugs.

sound is simply a pulse. to make continuous noise you need continuous pulses.
dc does make a noise, just once at the start. it makes one pulse. AC has continuous pulses.
welder ac is square wave so its literally DC being turned on then off. every time its turned on it make a sound pulse. hence you get a continuous sound.

the ac welding sound is not to bad unless you run at some high pitch scream frequency.
mix tig and double pulse mig is weird sound.

A graph of electrical current is typically shown in Amperage on the Y axis and time in seconds on the X axis.

If you graph DC you have a constant current (constant Amperage) per second which is a flat line at that amperage.
y (A) = mx(s) + b
In a DC application the formula is y = selected amperage since m (slope) = 0 (constant) and b = selected amperate at x = 0
It a flat line or meaning the frequency is 0hz. So at 120 amps the formula is y = 120 A.

Now think about AC. It alternates between positive and negative poles at a given frequency in the form of a wave.
A sine wave generator for example would be
y = Peak Amperage * sin(2pi * freq * t) + phase shift. Lets ignore phase shift.
y = A * sin(2pi * f * t) F is the frequency of the wave form.

That frequency creates an audible tone.

That's my best guess. I'm not much of an EE although I did study some of that stuff back in the day. Honestly looking this up reminded me of how much I have forgotten about math/calculus/trig haha.

https://en.wikipedia.org/wiki/Mains_hum

I always wear earplugs, regardless. But yea, same reason lightning produces thunder. It heats the fluid it it's vicinity (air), and it expands outward as a sound pressure wave. AC is the same, just on a much smaller scale, and the fluid is the shielding gas, which then transfers it to the ambient air.

bap_ wrote:https://en.wikipedia.org/wiki/Mains_hum

That's a good read.

I never thought of hum from a ground loop as being similar, but evidently it is.

Yeah, I could wear ear plugs, and I could also wear ear muffs. Truth be told I would rather hear the hum... not too crazy about having $#!T in or on my ears...

I guess it means you need to turn the music up louder...

It is just the way it is.. We can thank physics for that. Like the other guys said. It pulses and each pulse is like a starting DC TIG sound but because it alternates and starts every time it pulses it makes the loud noise all the time..

We cant get around it but we can use earplugs or play some music in the headphones if that's your thing. Just make sure that your welding helmet keeps you protected and don't jeopardize the safety.

Also it may be interesting this research paper about the welding noise as the health hazard.
https://www.tandfonline.com/doi/abs/10. ... ode=twld20
I read it a few days ago somewhere on reddit someone linked to it.. Maybe you will find it interesting. It is always good to protect yourself from things that bother you while working whether that is noise or arc flash it does not matter.