NTUU “KPI”, UFU, PWI TQC E1815-01 Ponomarev V., Slivinsky A.

MIG/MAG spray and streaming metal transfer modes

- Welding conditions for these metal transfer modes

- Their advantages and limitations

NTUU “KPI”, UFU, PWI TQC E1815-01 Ponomarev V., Slivinsky A.

Short-circuiting

Globular Streaming rotating

Streaming

Spray

MIG-Pulsed

Transfer modes versus welding current and arc voltage

Ua

Iw

Transition current

CO2, or argon based mixtures Argon based mixtures

NTUU “KPI”, UFU, PWI TQC E1815-01 Ponomarev V., Slivinsky A.

Globular – spray transfer transition

Current

Transition current

Rat

e o

f d

rop

let

tran

sfer

Dro

ple

t d

iam

eter

180 A Iw < Itr (190 А)

AWS ER70S-61.0 mm; Ar2%O2

211 AIw > Itr

Iw

Femz

250 A

Iw

Femz

Iw

Femr

NTUU “KPI”, UFU, PWI TQC E1815-01 Ponomarev V., Slivinsky A.

Transition current for different electrode materials and diameters as well as for

different shielding mixtures

Electrode wire material Electrode wire diameter, mm

Shielding mixture Transition current, А

Low-carbon steel

0,81,01,21,6

95%Ar + 5%CO2

140180240280

Low-carbon steel

0,81,01,21,6

80%Ar + 20%CO2

160200275280

Stainless steel

0,91,01,21,6

98%Ar + 2%O2

170170225285

Aluminium

0,81,01,21,6

Argon

90 - 95100120

170 - 180

NTUU “KPI”, UFU, PWI TQC E1815-01 Ponomarev V., Slivinsky A.

Examples of spray metal transfer

1 mm; Ar+5%O2; 197 А

The welding current slightly exceeds the transition current level

1 mm; Ar+2%O2; 211 А

The droplets are transferred in line with electrode rather than along the shortest path between the electrode and workpiece that is typical for this mode of the metal transfer.

NTUU “KPI”, UFU, PWI TQC E1815-01 Ponomarev V., Slivinsky A.

The spray transfer can be experienced at different arc lengths

Melting rate: 8.1 m/min 8.8 m/min 9.5 m/min

The shorter is the arc, the longer becomes the electrode extension (provided the contact tube – to - work distance is kept changeless) and, as a result, the electrode gets more intensive preheating by the current and therefore its melting rate rises (low-carbon wire of 1 mm and 211 А for all three tests).

NTUU “KPI”, UFU, PWI TQC E1815-01 Ponomarev V., Slivinsky A.

Welding conditions and application sphere of the spray and streaming transfers

Welding conditions for spray and streaming transfers:

1. High arc voltage and welding current;2. Shielding: argon based mixtures.

MIG/MAG spray and streaming transfer application is restricted to welding only in the flat position because, in spite of the fact that all droplets are getting into the weld pool, the pool itself is too large to be properly controlled when welding in the vertical or overhead position.