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how come the flat mig cwb test has such a high (85%) failure rate for first attempt? Almost always the reason they give is lack of fusion in the root pass(s)
Reply:I suspect it's because most people don't pay attention the first time. It is not a difficult test but if you don't run it in hot and stay on the leading edge of the puddle there will be enough lack of fusion to have the coupn open and fail.Drag it in and make sure you fuse each pass and you will do fine. Most of the failures in our shop are lack of fusion right down the middle - little fusion between the two first passes.
Reply:Most people botch the first two passes. Weld the square side first, and then weld the bevel side. Stay at the leading edge of the puddle, have sufficient heat and proper gun angle and you can't go wrong. It's probably the easiest test I've done. When I did it, the test was two root bends and one face bend.Last edited by mb_welder; 04-24-2011 at 01:59 AM.
Reply:I take it this is short-circuit rather than spray?Have we all gone mad?
Reply:The first thing is to notice that the fillet weld is to be a maximum of 5/16th inch. People think that the weld must be 5/16. In actual fact you are faraway better to make a SMALL, fast and hot weld bead with the arc at the leading edge of the puddle. The whole purpose of that fillet is to get good fusion in the corner. The flat plate test is done hot in spray mode. You will be required to restart at the location directed by the supervising inspector. It is important that you clean your bead completely of any trace of glass. In the shop I worked in we would set up one grinder with a new sharp wire brush. Restart ahead and track into the old crater or start behind and track into the crater. In any case make sure your restart is sound. It is a good idea to practice a few dozen restarts before you do the test on the machine you are going to use to confirm it will restart and tie in the crater correctly. Snip the wire every time you restart. Fill it up making your beads hot and flat. You can cap with a wide weaving pass or two passes side by side. It is your choice. I prefer two beads to prevent the possibility of cold lap at the edges. Your plate will get quite hot. To even out the beads I just turn the plate around to change the direction of weld. The end of the small plate gets super hot at the end of the bead and the bead tends to flatten out more. Changing directions moves that flattening out to the opposite end each time. If people are having 85 % failure rate they are not being given the guidance and support of their foreman/welding supervisor. Trying to remember with .045 metal core wire we would run around 27.5 to 28 volts and around 300 to 350 inches per minute.Last edited by lotechman; 04-24-2011 at 09:12 PM.Reason: not completed
Reply:Hmmm, I failed it my first time. Face was flawless, and the root opened up like a magazine.[Account Abandoned 8/8/16 Please Do Not Attempt Contact Or Expect A Reply]. See you on YouTube! -ChuckE2009
Reply:It would seem to me that if your failing a 1G test using spray transfer, either your machine is setup quite poorly or you simply cant weld.Are you required to have a restart in the root bend?Have we all gone mad?
Reply:Actually there are two restarts. You run about 2/3 of the length of the test piece with a fillet weld. That area becomes one root bend. You run a bottom groove weld between the fillet and bevel side for about one third. That becomes the second root bend. The stops are witnessed and marked by the inspector. The FG test makes sure that you can do proper restarts both with a fillet and a groove weld. Like snO said it is pretty hard to fail. Go fast to keep the arc at the leading edge. Don't try to maximize buildup. More passes is better.
Reply:that seems to be some good info, too bad my sup. never told me that when he gave me the test today, told me to do my root passes today and he will inspect them tomarow, I hope he passes them, he is a bit of a hard *** when it comes down to welding... but then on the other hand cant weld there unless your certified for 1G |
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发表于 2021-8-31 23:37:40