is MIG polarity important?

By supermechanic (**)

Date 03-09-2003 16:38

Only need to change when using flux core. If not using flux core, don't change it.

By Michael Sherman (***)

Date 03-10-2003 12:15

And then only on some flux core wire, not all of them.

Mike Sherman

By Ian Taylor (*)

Date 03-10-2003 13:07

Mike, Can you give a brief summary of -ve flux wire vs. +ve flux wire (ie how differently they weld, etc). I was thinking of having a switchable polarity on my 130amp Mig (see previous post) but if I can get a flux wire to suit the machine and the job (mostly mild steel and occasionally CrMo kart frames) then I will not bother. (I don't want to get another type of gas so I would use the flux wire gasles)

Regards
Ian

By Michael Sherman (***)

Date 03-10-2003 14:51

Ian, I use E71T-1 gas shielded (75/25 or CO2) in the shop on DCEP in a spray transfer mode, I like this wire alot. Outside in the wind I use E71T-11, but it does require straight polarity (DCEN). Some electrodes that are DCEP and self shielded are: E71T-3, E71T-4, E71T-6.
Mike Sherman

By Ian Taylor (*)

Date 03-10-2003 16:12

Mike, I've been trying to read the specs of the three wires you quoted (-3, -4 and -6) on various supplier websites but I'm becoming more and more confused. Which wire would you recommend as a general purpose self-shielded wire. I am not a professional welder however I do quite a lot of welding as a hobby to support my main hobby (go-karts). As mentioned earlier I modify, repair and occasionally fabricate from scratch go-kart frames which are a mixture of mild steel and CrMo. The main reason for looking at self shielded wire (DCEP) is so that I can carry my MIG welder in the van to be able to do repairs at the circuit without carrying the Argoshield bottle with me (here in the UK the insurance implications negate us carrying oxy-acetylene in the van). Your input would be very much appreciated.

(ps. all the CrMo go-kart frames are Mig welded by the various manufactures - very few (if any) are TIG'd. Tube is 32mm dia and 2mm wall thickness)

Regards
Ian

By Michael Sherman (***)

Date 03-10-2003 18:16

Ian, my son races go carts. It is quite an interesting sport. He races dirt track, alcohol burning Briggs & Stratton engines. Very fast. I would consider an E71T-3 These are designed for thinner material and not much penetration beyond the root. Use on up to .187" material and single pass applications only. Use E71T-4 on multiple pass applications.

By Ian Taylor (*)

Date 03-14-2003 09:53

Mike. I really appreciate your replies. I will have a go with the wire you suggest. Incidentally, two of my sons race karts (2-cycle engines) and I used to race 2-cycle, 125cc shifters. Karting is great fun, very fast and is providing an excellent insight for my sons who are interested in all things of an engineering nature.

Many thanks
Ian