Machine thickness ratings?

admin

I'll start by saying I'm not a pro, but I can MIG and TIG fairly decent. One thing I always wondered about were the material thickness ratings the manufacturers give their machines. For example, right now I have a Miller Diversion 165 and a 135 amp/120v Lincoln MIG, both are rated for 1/4" or so. A couple years ago  I made an exhaust for my VW. I only had the Lincoln MIG then but I had to weld 16g 304 pipe to a mild 1/2" turbo flange. Obviously  a 120v machine isn't gonna do 1/2" straight through, but that pipe to the flange worked out pretty well. Hell I think I coulda did a 1/2" butt weld on that machine it I grooved the hell out of the  front and back and made like 2 passes each side.Anyway, I assume that they go by what the machine can fully penetrate in a single pass, am I correct?
Reply:Originally Posted by blaziniI'll start by saying I'm not a pro, but I can MIG and TIG fairly decent. One thing I always wondered about were the material thickness ratings the manufacturers give their machines. For example, right now I have a Miller Diversion 165 and a 135 amp/120v Lincoln MIG, both are rated for 1/4" or so. A couple years ago  I made an exhaust for my VW. I only had the Lincoln MIG then but I had to weld 16g 304 pipe to a mild 1/2" turbo flange. Obviously  a 120v machine isn't gonna do 1/2" straight through, but that pipe to the flange worked out pretty well. Hell I think I coulda did a 1/2" butt weld on that machine it I grooved the hell out of the  front and back and made like 2 passes each side.Anyway, I assume that they go by what the machine can fully penetrate in a single pass, am I correct?
Reply:I've seen a couple of the smaller 110 volt machines say: Maximum thickness = 3/16"*The asterisk note at the bottom of the page said "Multiple pass". Always read the fine print!
Reply:Yes, some manufactures do inflate the specs, striped down units are famous for this. On a good day, going down hill with the wind, on waxed ice........
Reply:I think most welders would be surprise how little penetration ( depth of fusion) into the base metal is achieved with any given process. The  chemical composition of the admixture of weld metal and base metal is as least as important as the depth of fusion. Many small mig units are set up tu run self shielded flux cored electrode/ filler metal. This typically contains a great amount of manganese which can lead to a brittle weld if use to weld more than three passes. The other issue with the small machines are their duty cycle and their suspectability to damage from heat build up. It simply becomes to costly to run enough beads to make a big weld.
Reply:as dsw says.. i was welding some 1/2" steel today with 1/8 7018 at 135 amps. i ran out of 1/8, and tried to continue with some 3/32 i had at 100  amps. got some cold wormy beads and ground em off.and no point in a 1/2" weld on metal 1/16" thick..
Reply:Just a few notes.  The rule of thumb and nothing more than that is 1 amp for each .001" of plate being welded.  There is more to it than that, but its a guide.Next note, you will probably never get more than 100 amps out of your 110 volt mig welder regardless of what it says on the front.Read the sticky about 110 volt migs.David Real world weldin.  When I grow up I want to be a tig weldor.
Reply:Originally Posted by David R...........Next note, you will probably never get more than 100 amps out of your 110 volt mig welder regardless of what it says on the front.
Reply:machine thickness ratings are guidelines there's no standard for testing or rating. Industrial machines don't even list it. It's assumed you buy based off of rated output and duty cycle. Of course the manufacturers are gonna pump their numbers by saying they can do thicker material than what is practical.anyways you can do unlimited thickness with those little 110 machines, just preheat a bunch, and get used to multipass welding!  It may take longer but it's possible.
Reply:nobody mentioned duty cycle. at 100 amps an20 percent cycle,you may have close to 100 amps at the start of a butt weld on quarter inch materia, after an inch of weld, your looking at maybe 85 amps.those 110 volt machines are excellent they just take a long time to finish a weld on something like half inch stuff because they cant carrie the amperage long enough to melt the base metal properly.the 100 amps that i weld with on my 225ranger is for more powerfull cause it never exceeds the duty cycle[all rated at 100 percent],3 inches down the line never skipping a beat which causes the metal to heat up much more and fuse properly.also,that wire feeders using.030-.035.an eighth inch electrode deposits way more filler.not to say those little machines arent capable there just not practical for heavy stuff.niether is mig[less youve got a bigger machine]Last edited by ranger225; 02-09-2010 at 10:21 PM.Reason: misspell
Reply:I like to set my settings one "suggested setting" up, like if 3/16 says 18 volts 280fps I like to put it at 19 volts 320fps. on my 110 mig I pretty much just leave it cranked up all the way, after the whole mig like tig discussions on here, when I have time I'm going to mess with different wire speeds that aren't close to the suggested settings"Obstacles are those frightful things you see when you take your eyes off your goal"   -Henry Ford
Reply:If a hobbist machine says it will do a !/4'' max count on it doing an 1/8" maybe 3/16" in a pinch. Expecting any more will just end up p*ssing you off.Tough as nails and damn near as smart
Reply:Originally Posted by ranger225nobody mentioned duty cycle. at 100 amps an20 percent cycle,you may have close to 100 amps at the start of a butt weld on quarter inch materia, after an inch of weld, your looking at maybe 85 amps.those 110 volt machines are excellent they just take a long time to finish a weld on something like half inch stuff because they cant carrie the amperage long enough to melt the base metal properly.the 100 amps that i weld with on my 225ranger is for more powerfull cause it never exceeds the duty cycle[all rated at 100 percent],3 inches down the line never skipping a beat which causes the metal to heat up much more and fuse properly.also,that wire feeders using.030-.035.an eighth inch electrode deposits way more filler.not to say those little machines arent capable there just not practical for heavy stuff.niether is mig[less youve got a bigger machine]