GMAW Spray 2

[roguebear58]

I am reviewing a WPS for GMAW. The weld progression is listed as "up". Are not Short circuit (which cannot be used on this job) and pulse the only GMAW methods that can be used out of position?

 

[DVWE]

GMAW Spray shouldn't be used for vertical welding. Assuming this is for mild steel, there are a few basic things to check:

1. Shielding gas. Probably is some mix of Argon. If it is, then 80% minimum is required, 90% minimum is preferred.

2. Mode of metal transfer listed on WPS is Spray.

Both of these are essential variables which need to be addressed in the WPS.

 

[gtaw]

Spray is limited to flat grooves and flat and horizontal fillets.

The amperage would have to be above the transition amperage to ensure spray mode transfer is achieved. As mentioned, a high percentage of argon is required to ensure a steady spray. A 75% argon mix isn't going to be the best choice for spray. At best it will be unstable switching between spray and short circuiting.

The lower threshold for spray transfer on steel would be on the order of:

0.030 in. dia. - 175 amp
0.035 in. dia. - 185 amp
0045 in. dia. - 220 amp
0.060 in. dia. - 280 amp

Voltages tend to be higher for spray transfer as well. I would epect to see voltages above 25 V



Best regards - Al

 

[roguebear58]

thank you all for your responses. everything else in wps is fine. the "up" set off a flag for me. and it appears that this is true on every gmaw process this particular shop has.thought maybe there had been a revision i was not aware of. thanks again.

 

[Mr168]

I have, more often than not, seen "Up" used as a bit of a misnomer for "you shall not run this downhill" on both PQR's and WPS's, more so on WPS's as a change in uphill vs. downhill is an essential variable for welder performance qualification.