welding different thicknesses of steel

By Lee90071 Date 08-31-2001 17:41

I have a general question regarding Mig welding different thicknesses of steel. I am working on a race car, have taken a basic arc/mig welding class at my local community college, and I am experiencing blow outs when welding a 3/16" race seat frame to the floor pan of the car. I was trying 35 flux core welding wire, using a 30 amp/30% duty cycle and medium speed wire feed. The floor pan is 1/16" thick, or about that and seems to have a high iron content. I tried welding 1" at one end and then the same at the opposite end, to try and prevent too much heat build up, but still get blow outs in the floor pan steel. Should I try a small wire? Since I'm working outside, I have opted for the flux core wire as it's windy enough that using gas seemed futile. Any suggestions would be greatly appreciated. Also I'm using a Clark 130 EN welder.
thank you

By GRoberts (***)

Date 08-31-2001 22:35

Welding of 3/16" to 1/16" steel can definately be done with the equipment that you have. I have similar equipment and electrodes at home for playing around with. I have tried both the .035" and the .030" self-shielded FCAW electrodes in mine, and have had sucess (after many trials and tribulations) with both. The .030" electrode would be the easier of the two to weld the thin metal with, but it could be done with either. The key is machine setup and technique. I don't know what amps or volts I am running because the silly knobs are just labeled with letters and numbers that do not indicate any actual values, but I tend to run my machine near the top to middle of the voltage range, and the bottom of the wire feed speed range to get the best results on thin material. Possibly more important though is the welding technique. Make sure when you are welding, you arc is concentrated on the 3/16" thick material. When you puddle starts to build up, and you are sure you have fusion with the thicker material, move the arc across to the thinner material just long enough to get the bead to wet it, and then move the arc back onto the thicker material. If you can get some scraps to practice on, you can play with machine settings and technique before blowing holes in your floorpan.

Hope this helps

By guy

Date 09-08-2001 08:12

If at all posible go to .023 solid wire with CO gas.The CO gas helps in windy conditions and the .023
wire is great on thin metal,I have a welding business and I never use flux core on thin metal.Flux core
seems to get much hotter and warp more than with gas.This is just my opinion but I hope it helps you.

By THS-CWI (*)

Date 09-09-2001 01:08

I.ll agree with guy---if you can't use GTAW (TIG) use solid wire with CO2 shielding. I've done a lot of 18ga. in the wind and it works. Good Luck.

By Paul Brown Date 09-24-2001 15:41

75%Argon25%CO2 will work even better, as the straight co2 will tend to penetrate more as it is a reactive gas, not inert, and will also give less splatter and a better looking weld. remember to keep the most heat on the thicker material, then when it melts, push over to the thin stuff, good luck, Paul

By Lee90071 Date 11-29-2001 20:15

My heartfelt thanks to all that replied. I did get a bottle of 25/75 plus .023, .030 and .035 solid wire. With the thinner metals I did practice on a few scraps and found the settings that worked best, giving good penetration without warping or burn through. The car passed all inspections as was/is certified by the sanctioning body. Thanks again for all the help!