mig/mag spray and streaming metal transfer modes
DESCRIPTION
MIG/MAG spray and streaming metal transfer modes. - Welding conditions for these metal transfer modes - Their advantages and limitations. CO 2 , or argon based mixtures. U a. Argon based mixtures. Transition current. Globular. Streaming rotating. Streaming. Spray. - PowerPoint PPT PresentationTRANSCRIPT
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.