Electronics > Mechanical & Automation Engineering

grease for tig welder solenoid (gas flow switch)?

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coppercone2:
So I am tying up loose ends and I came to the gas solenoid.

It is simple, spring, metal slug, plastic housing, o-ring. I thought it was a bit rough when I was actuating it so I took it apart and ultrasonic cleaned it. I put a light wipe of oil on the metal slug and spring just so it does not corrode after cleaning during bake out. I did not reassmeble it yet so I can still clean the spring and metal cylinder/slug. I believe there was a tiny amount of grit in there that was making it run with a tiny 'crunch'. It is just a cylinder pushed by a spring that is retracted by the magnetic field of the solenoid.

Should I apply any lubricant on it? I.e. like air tool oil or something. Its for argon. Or a thin coating of grease, like I thought silicone grease maybe. Or are they meant to run clean/dry? IDK if its considered 'contamination' of the weld if there is a tiny bit of grease on that slug.

TERRA Operative:
We never used to use lubrication. The inevitable workshop dust will stick to it and gum it up.
The actual valve body was usually a sealed, non serviceable part and you don't want any oil inside where the gas goes.

If a good cleaning didn't fix it, it should be replaced. We usully used aftermarket ones that were relatively cheap (price, not quality) as there weren't too many variations in design so a couple part numbers would cover most welders, and customers wanted the welder fixed fast at lowest cost.
We didn't notice any real difference in lifetime between the genuine or aftermarket parts, in fact often the genuine item was the same part we were buying aftermarket, just stuck in a bag with an 'official' welder brand name. ;)

coppercone2:
Well I figure it should be pretty good if its just hooked up in to the argon tank ? On a 200 it comes apart easy the valve is press fit in a o-ring and the chassis bolt hold it together

I also noticed that its just a metal-plastic seal. I thought there would be rubber or something on the cylinder, but it looks like it just makes contact with the plastic (like a rubber end piece for the metal rod), it just has a lathe cut flat on it that touches a flat plastic to make a seal. Since there is no deformable stuff I figure it can't be that tight.

I wonder if it could be missing parts? How gas tight should they be? But I also don't see how there could be rubber attached to there either, unless it was glued on and someone lost it.

Is metal to hard flat plastic a common 'valve seal" for these things? I figured there would be a cap on it like a syringe plunger. The gas regs all use rubber too.

What I am saying is that the slug is just lathe cut flat on the end (with spiral pattern) and it sits on a smooth plastic ring that is part of the valve body to block gas flow.

Do you think I am missing a piece? I think the term would be 'seatless' or maybe 'hard seat' . I could glue a rubber disk on the bottom, but I am not 100% sure if its supposed to have one.

TERRA Operative:
We rarely ever took them apart and I have no idea what yours looks like without a picture.

Usually, unless the service manual specified that they were serviceable, if they were playing up we just threw them in the scrap metal bin and installed a new one.

Was no good spending an hour or so poking away at the valve, only to have to do a site visit to replace it for free when it failed again a few days later anyway. ;)

coppercone2:
oh no this one is dead simple.

Its just 2 plastic parts, held together by 2 screws to the electromagnet part.

A bottom valve body, and a stem body. THe stem has a o-ring on it that press fits into the valve body. The stem has a spring and magnet inside of it.

So you do is remove 2 screws, then yank on the stem with fortune cookie cracking strength and it comes apart, since all you need to do is pull a o ring out of a 4mm deep hole. Then the metal slug and the spring slide right out.

Honestly one of the most simple objects I have seen. I think its very elegant. No snap hinges or nothing, it relies on the sandwich to the coil part to hold it together, otherwise about 1 psi of pressure will cause the top to pop off.

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