How to TIG Weld Aluminum part 3 - AC frequency settings

A lot of newer TIG inverters have a setting that allows adjusting the frequency of the alternating current for tig welding aluminum.

If you use a TIG welder with AC frequency settings, and you are trying to learn how to tig weld aluminum, this video is for you.

This video provides practical applications for AC frequency settings.

...Introducing the New WeldMonger Challenger TIG kit that includes the most frequently used Cups. 

challenger kit 17 front
challenger kit 17 contents

see more tig welding aluminum videos or go to the main TIG welding page

How to TIG weld aluminum parts 1 and 2

How to tig weld aluminum part one was about differences in polarity, why we tig weld aluminum on AC and all types of examples on different weld joints along with lots of arc shots you can see part one here

PArt 2 is about AC balance, tips for feeding the filler wire and a lot more.  you can see part 2 here

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I asked for comments and questions in part 1 of this "how to tig weld aluminum" series.

I got a lot of them.

..and one of the frequently asked questions was about AC frequency applications.

When do you use higher frequencies? and when are lower frequencies better?

What is a good all around frequency setting?

And does it even make that much difference?

Applications for lower AC frequency settings

I attended the Lincoln Electric advanced motorsports class a few years ago and I remember that they had an aluminum head with sections milled out for practice on welding aluminum castings.

I tried to weld it using 120hz and had a hard time even establishing a puddle.

Someone suggested using lower frequency setting because the Lincoln instructor told him it worked better on thick aluminum castings.

So I lowered the AC frequency setting to 50hz and I was off to the races.

Ever since that day, I have been using lower frequency settings to get more heat into thick aluminum castings.

Applications for Higher AC frequency settings

For thin tee joints, and for thinner lap joints, a higher setting seems to help a bit.

60 hz and 120 hz both worked fine for the lap joint in .063" 6061 aluminum

250 hz worked for a tee joing in .063" 6061 aluminum.

but the high pitched sound from 400 hz was just too annoying.  ear plugs are definitely needed for tig welding at 400 hz

What if your tig machine does NOT have an AC frequency setting?

It is just not that big of a deal.

As you saw, AC frequency has an effect on tig welding aluminum but the hands and eyes of a good welder can also have a dramatic effect on the final weld.

Doing things like using the right size electrode for a job, using the right cup, the right gas, the right technique, etc. all make big difference.

PRO tip... use a #5 cup with tapered tungsten for smaller beads

Sometimes these things can make as much or more difference than being able to adjust the AC frequency.

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