HF Tig welding

3 replies [Last post]
Mike b's picture
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Joined: 2013-10-28

So here is an interesting one. I have been in the field for about 27 years and this one stumped me.
I presently work in a welding shop. It is family owned and they own a bunch of old equipment. We have several welding positions for turning the part you are welding. These units are about 40+ years old. Here is my question.
Whenever a HF welder is used, I end up doing major electrical repairs to the units. I have tried to isolate motors and drives to reduce damage but I am still having problems. Any suggestions will be welcome.

mdshunk's picture
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Joined: 2014-03-14

Could you describe the nature of the repairs that become necessary to the equipment as a result of welding by the TIG process? I've done quite a bit of work on pipe welding fixtures that are motor controlled, and haven't experienced what you report.

Have you investigated the possibility of replacing the VFD and motor with a pneumatic motor and foot pedal?

Mike b's picture
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Joined: 2013-10-28

Basically, what is happening is these units use DC drives on the turning motor and AC motors to go up and down. What normally happens is we will either blow the DC drive or the motor. We have isolated the drive and that helps, however, depending on how they are welding the DC motor will jump and change positions. I have tried isolating the motor, which helped though did not completely stop it. Using pnuematics would help, though we do not have availability everywhere in the shop for air.

mdshunk's picture
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Joined: 2014-03-14

I haven't worked with DC drives in a very long time, so I can't really help too much in the area of their immunity to the high frequencies from the TIG process. I'm betting that the manufacturer of the drive would have some good ideas. If you changed this to an AC arrangement, there's a lot more I know of that would do the trick. DC drives have pretty much fallen out of favor, so it seems, in industry for new work.

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