Welding Processes

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Welding Processes

• by
• Dr. Susantha Pathirana
• Department of Production Engineering
• University of Peradeniya

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Welding processes

• Manual metal arc welding
• Spot welding
• Seam welding
• Electron beam welding
• Friction welding
• Submerged arc welding

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Welding requirements

• Heat source
• Parent/work material
• Filler material with fluxes or chemicals

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Spot Welding
FIG 03
FIG 04
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Spot Welding
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Seam Welding
FIG 09 (a)
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Seam Welding
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Arc welding (AC/DC)

• Heat distribution
• Temperature distribution
• Penetration
• Quality assurance
• Selection of welding parameters
• i. Voltage setting
• ii. Current setting
• iii. Welding speed
• iv. Electrode angles

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Power/ Heat sources

• Alternating Current (AC)
• Direct Current (DC)

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Manual Metal Arc Welding (MMAW)

• Machines / Plants
• Transformer
• Rectifier
• Generator (DC)
• - Open circuit voltage (OCV)
• - Short circuit current (SCC)

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What we expect in a weld

• Strength
• Quality - Thickness
• - Width
• - Appearance
• - Efficiency

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Strength
(Controlling factors)

• Adequate penetration
• Good joint design
• Proper welding position
• Selection of electrodes
• Composition of weld metal

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Penetration

• (Controlling factors)
• - Welding power ( W V x I )
• V- Arc voltage
• I - Welding current
• - Welding speed
• - Electrode angle
• - Arc gap

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Joint Design and Symbols Used
(BS 499 part 2 1980)

• Butt weld
• Fillet weld

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Welding Position

• Flat
• Horizontal
• Vertical
• Overhead

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Penetration
p
HAZ
Heat Affected Zone
P k Va Iß E?
Other configurations
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Welding circuit
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Machine Characteristics
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A
Welding machine
V

• Measure
• Voltage
• Current
• Arc gap
• Speed

Computer
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Computer Aided Welding

• On line monitoring for expected quality
• Useful in designing automatic (robotic) welding
• Online corrective action is possible