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I have a magnetic ground on my MIG machine, as opposed to a clamp. Is this a bad idea? I've never given much thought to it, I put it on there probably 5 years ago, but after poking around the site I haven't noticed anyone say anything about this kind of ground. I did notice last night that the nut that holds it on to the magnet did come loose, and now I'm starting to wonder if it's my cause for intermitten funky welds.
Reply:Hello independentcustoms, there are instances where the magnet on your ground could cause some arc instability issues. Generally these are most noticeable when the magnet is in a fairly close proximity to the welding that is taking place. If you are familiar with the term "magnetic arc-blow" this might be a case where that would apply. Set-up magnets can certainly effect the stability of the arc as well, they are generally fine for tacking-up, but I wouldn't suggest leaving them on a part when you are welding it. As you mentioned, you have likely read a bit about the "arc blow" topic, continue to read through that stuff and get an idea of the various ways that folks have addressed it. Best regards, Allanaevald
Reply:Yes, loose connections can cause poor welds.There is nothing wrong with the magnetic work connection, but they have some limitations. It can be tough to get a good connection due to the limited contact force, the weight of the lead may cause them to slide, fall off, or make intermittent contact, they are more likely to leave burns at the contact point than a good clamp, they only work with steel and certain stainlesses, the mag field can lead to arc blow and/or permanant magnetization of the material,etc.On the plus side: they are fast and convenient, they can be attached in the middle of a surface (often REAL handy) without welding on a tab, in some situations it is handy to have the lead able to pull off easily if something snags the lead.That said, we've got them in the shop and they are rarely used. Usually use a standard clamp or vise-tongs with a stud welded on for the lead.
Reply:Thanks for the help guys. I think I'll stop today and pick up a clamp. I've never really given it much thought, and always just figured I was having an off day when my welds suddenly take a turn for the worse. I'm sure I do have off days either way, but there's no sense in making it worse with a crappy ground. While I was doing some research on arc blow, I came across another problem I may have. I broke my my flowguage a couple years ago, and because I was too ignorant I simply put a Parker regulator on it with a pressure guage and went back to work. I'm now thinking my flow rates are too high.Last edited by independentcustoms; 10-07-2009 at 01:28 PM.Reason: I have a potty mouth
Reply:Excessive flow-rates can cause turbulence in the weld puddle and cause problems with the welds. So, if you can, certainly invest in a new regulator and see about setting it at the proper flows for the particular nozzle diameter that you are using. If you don't have a good sense of what that particular flow should be, try experimenting a bit by turning the gas flow down until you see porosity in the weld deposits and then gradually increase it until you no longer see the porosity. You might additionally add a bit more to ensure that you have enough gas. Best regards, Allanaevald |
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发表于 2021-9-1 00:42:28