Bernard Mig Guns

Date 05-29-2003 19:17

We have these guns in our shop and have had that happen here. Take the handle apart and look for bad connections. You might want to check the neck itself, the insulation between the brass part and the copper might be dammaged or gone, and are coming in contact with each other. I think the necks are replaceable, might have to bite the bullit and buy some new parts.

Rick

By jwright650 (*****)

Date 05-29-2003 19:34

Rick,
The new parts are cheap compared to someone getting the crap knocked out of them. I have taken these apart and know about the teflon insulation that you are talking about. The guys at the welding supply shop said that the gun getting hot and cooling off breaks this barrier down and it will fail at some point. My question is, "When" can you anticipate this failure and replace it before it happens again. This gun is fairly new, that blew apart in the welder's hands. I want to keep an eye on these guns and replace them or replace some parts as they seem to need them. This one caught us off guard and we're trying to figure it all out. Some of the welders hold the brass neck for better control, but I'm advising against it now that I've seen what can happen.
Thanks for your reply,
John Wright

By CHGuilford (****)

Date 05-29-2003 21:25

John,
From my experience, I have to say the necks of those guns should never be getting hot enough to break down the insulation inside, especially teflon. I would not let the vendor tell me otherwise.

The gas nozzle is a different story, those can get hot temperature wise. And electrically hot if there is spatter built up between the contact tip and the nozzle (of course then you are at risk of getting porosity from reduced gas flow). However....there is an insulator in the nozzle that prevents heat and electricity from flowing into the neck assembly, at least it is supposed to.

To hazard a guess about the accident, I would say the guy was tacking with the nozzle against the steel. But if the gun was as it should be there would not have been any problem. Has anyone in your plant disassembled the guns? Maybe they didn't reassemble them right? Are you using aftermarket replacement parts that might not be fitting exactly right; making contact somewhere it shouldn't? If not, then you have some defective welding guns that should be immediately replaced with new ones. In fact, they should probably be recalled.

We have used Bernard guns in the past; they worked fine. We now use Magnum 400s from Lincoln, mostly because the contact tips and other parts are cheaper through our present vendor. I have to say that ours see some rough use, especially as "substitute hammers" for fitting clips and small parts. Yet with all that abuse, our major problem is from broken triggers. I don't recall ever having a neck becoming live.

One other side point. We are often accused of hampering production by requiring too much PPE. But, every worker is required to wear at least "driver's" gloves for doing ANY kind of work, even pushing a broom (we provide them). The only exceptions are for using pencils and such, or where there is a greater hazard of getting caught in a machine, which is not often. Sumpin' to think about.
Chet Guilford

By Michael Sherman (***)

Date 05-30-2003 10:47

John, in the past we have used Bernard, Miller, Tweco and Lincoln guns. Two years ago I switched to all Lincoln Magnum 400's. All of our gun problems, including necks being hot, went away. Just my opinion, but consider biting the bullet and changing over to a better tool. I know this would be a major expense for a company your size, but I know how much one injured employee can cost.

Respectfully,
Mike Sherman
Shermans Welding

By jwright650 (*****)

Date 05-30-2003 11:55

Mike, Chet, Rick,
I have an AED (Automated External Defibrillator) in our First Aid arsenal and I am trained to use it. I certainly don't want to have to use it to jump start somebody just because we didn't use a quality part and they got zapped. This might sound to some like we are running scared because we've had an accident, but one employee hurt is one employee too many. We have good people and can't afford to lose any of them or have them out on an OJA.
John Wright

By jwright650 (*****)

Date 05-30-2003 14:46

Update:
I called the supply shop to inquire about the Lincoln magnum 400 series guns and I was told they won't handle the 3/32" dia. wire or the amperages we run, and that our Bernard guns are 600 amp guns. The mfg rep for the gun we use is coming to our shop to see this gun that blew up and he also wants to see the other two guns that are electrically hot at the neck.
My question to him will be how to determine "when" to replace it.
John Wright

By CHGuilford (****)

Date 05-31-2003 09:27

John,
I see you run bigger wire than we do. I never tried 3/32" wire in a Magnum 400 so I can't argue that. But I would hold the vendor's feet to the fire. They are not doing you a favor by doing business with you, it's the other way around. So maybe you should consider stirring up some good, healthy competition by inviting another vendor to look at the problem. Between them should be able to find you some guns that are durable, large enough, and safe to use. (Sorry 'bout that, Vendors; I just like to give back what I often get. My apologies to the honest, fair, hard working variety.)

But more seriously, John, I would look at the overall system you have of doing things to see if new products and new safety procedures make sense. It sounds like you already are to some extent, but I would look at how to make each job function , and person safer, from a different perspective.
Should everyone wear gloves? Should you switch to smaller wire and better guns? Will you lose too much in efficiency by doing that? Which wire size is less smoky? Can jigs or fixtures reduce the need for tack welding (which is when people are least likey to use PPE)? Are bigger guns causing carpal tunnel syndrome? And similar kinds of questions.

I'm not trying to suggest you re-invent your business; just to avoid the "We've always done it that way" mind set that often prevents us from stepping back and seeing a better way. (Hmm, that sounded a lot like- "Step OUT of the box!).
We had gone over 15 YEARS and over 2.5 MILLION work hours without a lost time accident until about a year and a half ago. (One guy dropped an angle just "wrong" and required surgery to his finger.) Since then we have built up to over 200,000 safe work hours and over 147 days without even a recordable incident. Until a couple of months ago, we had overtime for over 2 years running on all kinds of fabrication, big and small. I have tremendous respect for our company for achieving that record.

I didn't bring this up to brag. I brought this up because our company did it by "stepping out of the box" and by asking a lot of the questions like I mentioned above. At the same time we have managed to make some profits, even increased it in some situations. I honestly feel it is worth doing that, safety wise, and our fellow employees deserve the effort.

I'll climb down from the soap box now. Sorry for being long- winded but I hope it helps.
Chet Guilford

By JINX

Date 06-02-2003 19:48

John,
Are you using a self shielding FCAW or a shielding gas?
If using a shielding gas, what is the gas composition?
What is the electrode classification?
What voltage/amperage are you running with the 3/32" electrode?
Regards, Joe

By jwright650 (*****)

Date 06-09-2003 16:37

Joe,
I've been on vacation for the last week and have lots to read and catch up on here.
We use ESAB's Dual Shield 111-AC, E70T-1 w/100%CO2 @ 40-50cfh, AWS spec. A5.20. We run anywhere from 325-500 amps @ 26-33v.
John Wright

By JINX

Date 06-09-2003 20:42

John,
I hope you enjoyed your vacation, we all need time away from our daily routine. The reason I asked the parameter questions was to determine if you are at the high end of the duty cycle for a 600 amp air cooled gun.
According to the Bernard literature the 600 amp gus is rated at 60% duty cycle at 540 amps using 100% CO2 shielding gas. If you welders are making long continuous welds at 500 amps with possibly a short stick out, a contact tip flush with the nozzle, a 5/8" diameter nozzle the gun has a good chance of overheating. As you know when the goose neck overheats, that will cause damage to the insulation.
I would review the welding techinque, and consider buying one water cooled gun for evaluation.
Regards, Joe

By jwright650 (*****)

Date 06-09-2003 20:53

We went to the 600 amp guns several years ago because the 500 amp guns were overheating. I found out today from the Bernard rep that someone had lost the screws out of the holder and replaced them with longer than stock screws and it was tightened down too far and crushed the brass and therefore making a direct connection. I found two more guns just like this in the shop and are replacing them now. The rep told me to watch out for the set screw that holds the brass neck straight, that from the factory these have an aluminum block for the set screw to hold against and it falls out or was never put in there at the factory. Overtighening this set screw without the block in place punctures the brass neck shorting out the gun as well.
FYI
John Wright

By rhoople47 (**)

Date 06-04-2003 17:40

I didn't realize you were using such large dia. wire. Have you been using a water cooled gun? This might cut down on the rate of the degeneration of the insulation.

By jwright650 (*****)

Date 06-09-2003 16:38

rhoople47,
No, we haven't run the water cooled guns before.
John Wright

By rhoople47 (**)

Date 06-11-2003 15:40

John; I think th water cooled gun might help you, and the welder greatly.

Rick

By bspeirs (*)

Date 06-12-2003 01:36

One alternate to water cooled guns is an air cooled gun - http://www.pacmig.com/

I have never used one - anyone have anything good or bad to say about them?