So I just switched my welder from flux core (FCAW) to MIG. I am not used to working the bottle. When I went to weld on my new transmission cross member today, I noticed that my welds were looking kind of rusty. I figured that maybe my regulator got bumped or something, not a huge deal. I was also running a fan in the garage, so the air might be blowing the C25 shielding gas away. So I kept welding and tried to block some of the flowing air. The welds didn't look very good, like they were dirty, but some were shiny silver. When I got done, I shut off the power to the welder and went inside and showered up. Later, I realized that I didn't shut off the gas bottle. I went back out and tried to shut the valve, but it was already closed. So, I did a bunch of welding on a fairly important cross member with no gas. My question is: does running my welder with the gas off compromise the strength of the weld? Should I cut off the bracket and re-weld?
I would because the weld is not going to be worth anything strength wise in addition to all the contamination problems.
I agree. Cut it off, clean it up, and reweld it with the gas turned on. The weld you have there now is junk if the gas was turned off. Sucks, but the next time you will know in a few seconds that the gas is not on. Gene
might be hard to adjust the flow rate with the bottle off? see if your regulator has a flow gage, and make sure you know how to read it and adjust the rate to where it should be. If you make it a habit to make sure to check this each time you start welding, then you probably won't have that problem again.
I would cut it off and start over as well. Also make sure you switched the polarity of the machine when you changed from flux core to hard wire. It is an important step as well.
like he said, the polarity thing is quite important. Also if you do have an output flow guage, set it in the 25-30 cfm range, also do some practice stuff before you get into the frame work, figure out the best settings for the material you are working on as the machines guidelines tend to not work all the time.
I ran out of gas the other day and didnt realize it unitl I ran a long weld....ground down and the welds were good once ground a bit...but this IS the trans cross. I wouldnt take a chance....better that sitting on the side of the road wondering why you didnt take that extra hr. to fix it.
There are times when a weld may look fair after loosing on not having gas. But without a gas shield for regular mig wire you are guaranteed to have porosity. If you could put that under magnification you would see it. Removing it is tricky. You have to remove it all! Removing only part of it will cause the next good weld over it to also carry this porosity. Grind the shit out of it.
Okay, will do. Thanks for the responses. The regulator does not have a flow gauge, so I'll have to get one to prevent this mistake again. I did switch the polarity, but just didn't open the bottle. Thanks again for your help.
I didnt know they existed but some units have an internal regulator. I dont like them that way obviously you cant adjust the flow or even know it exists until its too late.
YOU NEED 3 things: 1-GAS (set at 12-15psi) is your atmosphere for a clean weld 2-AMPS set properly for the thickness of material and wire speed 3- CLEAN metal to weld (if its not grinded/sanded clean, it's not worth welding onto)
it's always windy IN my garage (Texas+10 giant fans)so I weld at 35cfm. but I get a killer deal on shield gas, and my supplier is within walking distance, so I don't mind.
if you really want to know how much gas is coming out of your gun you need a CFM gage not a PSI gage.
The gas not only provides a shield, but also aids in arc stability (ARGON) and penetration (Carbon Dioxide). In agreement with the others your welds will have to be removed and replaced. I would recommend getting a flow meter gauge for your rig, well worth the investment. I typically run around 20. Make sure you adjust the gas to a working pressure. To do this take the tension off your spool so that your not feeding wire. Hit the trigger and adjust your gas to the desired flow rate, this will ensure that you are getting that amount of gas when you are welding and not a lower rate.
Let's talk about polarity reversal for a moment please. I usually use flux core wire when my garage is open due to the breeze. I notice that I get much better penetration as well with the flux core and that I get more "build up" with regular wire. I've never messed around with changing the polarity. What exactly are the correct polarity settings for each type of wire. Thanks for bringing this subject to my consciousness.
Them french fried taters, mmmmhmmmm. "For MIG welding, the correct polarity is DC reverse (also known as electrode positive). Many wire welders come set for straight polarity (electrode negative), which is used for flux cored welding. Follow the instruction manual to set the right polarity. For more tips on proper MIG welding technique, go to www.hobartwelders.com. " From http://farmindustrynews.com/news/farming_mig_welders_machines/
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