Which AC frequency bandwidth is necessary ?

[cali_migweldig]

Hi guys,
my friends and I are from Germany and planning to buy a welding machine for hobby purposes.
We need an AC/DC welder, due to stainless steel and aluminum/magnesium.
We prefer a programmable machine, so we can use always the same settings for routine jobs.
A foot pedal is a must have, as far as I understood… or at least it is very handy.

We have 3 different welding machines from LCDVision (LCD Vision or LCV-Vision) on our list.
DIGI AC/DC 200P (230V)
D-INV 200P ACDC (230V)
D-INV 320P AC DC (400V)

They not only vary in welding current in AC mode:
DIGI AC/DC 200P = 20-200 A
D-INV 200P ACDC = 10-200 A
D-INV 320P ACDC = 10-320 A

They also vary in welding frequency in AC mode:
DIGI AC/DC 200P = 20 - 100 Hz
D-INV 200P ACDC = 20 - 150 Hz
D-INV 320P ACDC = 30 - 250 Hz

My 1st question is now, how important is a higher welding frequency in AC mode, than 100 Hz?
My 2nd question is now, how important is a lower welding current in AC mode, than 20 A?
My 3nd question is now, how important is a higher welding current in AC mode, than 200 A (or real 200 A)?

I say thank you in advanced for your support and your opinion.

Cali_migwelding

p.s. here are the links to the machines, if you are interested.

DIGI AC/DC 200P for 649€

D-INV 200P ACDC for 849€

D-INV 320P ACDC for 999€

 

[hotponyshoes]

For welding on a/c you might also want to check the duty cycle at the power you intend to use the machine at.
I expect that the 3-phase version will be much better in the duty cycle aspect and the specs above look better than the other 2 as well.
You do say hobby use though so you might not need anything like what it offers.

I have a 200a machine for hobby use and a 230a machine in the workshop. I can certainly notice the extra 30amps on thicker sections but I have welded lumps of 10mm together with preheat with no problems for hobby use on stuff that's not got any real structural requirements. Others on here will be able to advise on how much power you will need if you let them know what thicknesses you will be welding.

I have done all sorts of hobby stuff in alloy, on frequency I have never gone below 50hz and I dont think i have gone above 100hz. Actually i have tried above 100hz but i dont notice much difference once i go over that apart from the noise gets a lot more annoying.

I think power wise on aluminium I have maybe only gone as low as 40a or so for maybe 1.5mm sheet. I have done some thinner stuff like .8mm sheet but that's tacking it through holes onto thicker framework. I dont really know as i set the welder to full power and use the foot pedal. Again, only important depending on what thickness you are welding.

 

[hotponyshoes]

Given the choice (if I had currently had a 400v power supply) then for an extra 250euro I would get the 320a machine. Even if you dont need more than 200a it is (should) last a lot longer as you wont be stressing the limits of it in any way.

I have found that even for hobby use that the welding torch gets very hot very quick when welding aluminium so if I had a fixed budget of 1000 I would be buying the cheaper machine and a water cooled torch to go with it.

 

[Munkul]

My 1st question is now, how important is a higher welding frequency in AC mode, than 100 Hz?
- Not very, unless you're welding very thin sections and need to focus the beam. For general usage, 60hz is actually fine. I tend to use between 60 and 120 mostly

My 2nd question is now, how important is a lower welding current in AC mode, than 20 A?
- not very, unless you're welding sub-1mm sections or trying to weld coke cans together.

My 3nd question is now, how important is a higher welding current in AC mode, than 200 A (or real 200 A)?
- you can't use the amps you don't have 200 amps from a cheaper machine will weld 6mm thick alloy, AT A PUSH.

If you have 3 phase 400v, then my advice is, get a 3 phase machine. Exactly what hotponyshoes said, really.

 

[Cheesie]

I use frequency above 2k when tacking external joint on 2mm on an ewm in work to concentrate the arc then turn it down below 2k when welding