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DEFINITION OF SPRAY TRANSFER. KELVIN LONGDEN PROCEDURES DEPARTMENT. PRESENTATION OVERVIEW. Modes of metal transfer Factor affecting metal transfer Spray transfer data Guidelines for spray transfer. MODES OF METAL TRANSFER. Short-Circuiting Transfer (GMAW-SC) Globular Transfer (GMAW-GL)

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definition of spray transfer

DEFINITION OF SPRAY TRANSFER

KELVIN LONGDEN

PROCEDURES DEPARTMENT

presentation overview
PRESENTATION OVERVIEW
  • Modes of metal transfer
  • Factor affecting metal transfer
  • Spray transfer data
  • Guidelines for spray transfer
modes of metal transfer
MODES OF METAL TRANSFER
  • Short-Circuiting Transfer (GMAW-SC)
  • Globular Transfer (GMAW-GL)
  • Spray Transfer (GMAW-SP)
  • Pulsed Transfer (GMAW-P)
short circuiting transfer mode gmaw sc
SHORT-CIRCUITING TRANSFER MODE (GMAW-SC)
  • Repetitive short-circuits (the arc is extinguished) between the wire and the welding puddle.
  • The parameters are at their lowest range for the GMAW process
  • Application in all positions for thin sheet and for the root pass welding of pipe.
  • Difficult to apply successfully to thicker materials because of the low values of amperage and voltage may result in fusion problems.
  • Not prequalified.
globular transfer gmaw gl
GLOBULAR TRANSFER (GMAW-GL)
  • Droplet transfer is nonaxial with a diameter larger that the wire size.
  • In argon-rich gases this mode of metal transfer occurs with parameters below the spray transition but above that for short-circuiting.
  • Spatter can be excessive, rough-looking beads, glass-like silica island formations.
  • Limited use compared to short-circuit and spray transfer modes.
  • Not considered prequalified.
spray transfer gmaw sp
SPRAY TRANSFER (GMAW-SP)
  • Molten metal is transferred across the arc in a continuous stream of fine droplets.
  • The arc is stable.
  • Current and voltage above critical transition values and the use of argon-rich gas mixtures.
  • High deposition rates and desirable fusion and penetration characteristics.
  • Considered prequalified.
pulsed transfer gmaw p
PULSED TRANSFER (GMAW-P)
  • Periodic surges or pulses of current above the transition value for spray transfer which causes the detachment of droplets.
  • Between the current pulses, the arc is maintained by a relatively low background current.
  • Average current can be well below the transition value - weld appearance resembling that obtained in spray transfer.
  • Not prequalified
metal transfer across the arc in gmaw
METAL TRANSFER ACROSS THE ARC IN GMAW
  • The mode of the weld metal transfer is determined by the following factors:
  • Welding current
  • Electrode size
  • Electrode composition
  • Electrode stick out
  • Shielding gas
gas mixtures for gmaw for carbon steels
GAS MIXTURES FOR GMAW FOR CARBON STEELS
  • The gas mixtures commonly used for gas metal arc welding of carbon steel are:
  • Argon / Oxygen - 98% Ar / 2% O2 , 95%Ar / 5% O2
  • Argon / Carbon dioxide - 90% Ar / 10% CO2 , 85% Ar / 15% CO2 , 75% Ar / 25% CO2
  • Argon / Carbon dioxide / oxygen - 91% Ar / 5% CO2 / 4% O2, 90% Ar / 8% CO2 / 2% O2,
gmaw gases that produce similar results
Group A - Lows Energy Mixes

Argon + 1-10% oxygen

Argon + 2-10% CO2

Argon + 1-10% oxygen + 2-10% CO2

Group B – Medium Energy Mixes

Argon + 14-20% CO2

Argon + 1-5% oxygen + 14-20% CO2

GMAW Gases That Produce Similar Results
spray transfer guidelines
Spray Transfer Guidelines
  • Shielding Gas – Argon rich - maximum 20% CO2
  • Welding parameters in accordance with graphs
  • Look and sound of the arc