Semiautomatic arc welding problem - Edwards @ Wiki

1 General knowledge of semi-automatic arc welding

Question 1.1 Outline of welding

• Welding classification
  • Fusion welding: locally melted and solidified to bond
  • Insulation displacement: Heat and apply pressure to the joint and bond
  • Brazing joint

Question 1.2 Operation of semi-automatic arc welding

1. The arc length is kept constant automatically
2. Wire feed automatically
3. Torch is manually operated

Question 1.3 Wires and welding rods in semi-automatic arc welding

• Semi-automatic arc welding wire
  • Solid wire
  • Flux-cored wire

• Self shielded arc welding wire
  • No shielding gas required

• TIG welding
  • Welding with a thin rod-like filler rod in principle

Question 1.4 Characteristics in semiautomatic arc welding

• The arc length is kept constant automatically

Question 1.5 Characteristics of solid wire method in semiautomatic arc welding

1. Good penetration and high efficiency
2. The effect of shielding gas decreases due to the flow of the atmosphere
3. Start of welding due to short circuit transition by torch operation part

Question 1.6 Characteristics of flux cored wire method in semi-automatic arc welding

1. Excellent bead appearance against slag generation
2. Arc stabilized
3. Wires that can be welded to AC power supply also exist

Question 1.7 Gas in semi-automatic arc welding

1. Carbon dioxide gas in MAG welding suppresses contamination
   of atmospheric oxygen in molten metal
2. Semi-automatic welding without shielding gas also exists
3. Shield gas of mixed gas also exists in semiautomatic arc welding

Question 1.8 Gas in semi-automatic arc welding

1. Intentional mixing in MIG welding Promotes diffusion
   of weld metal by mixing O_{2} gas
2. CO_ {2} and Ar mixed gas exist for semi-automatic arc welding
3. Suppress moisture to supply gas in semiautomatic arc welding
   and prevent corrosion

Question 1.9 Type of gas in semiautomatic arc welding

1. CO_{2}
2. CO_{2} + Ar
3. CO_{2} + O_{2}

Question 1.10 Transition form of welding 3 type

• Spray transition type: Using a large current and good bead appearance
• Short circuit transition type: Used for welding thin plates
  and welding all positions using small current
• Globular transition type: Solutions move more than direct wire
  Note:Globule polymer
  • Drop transition: use low middle current with MAG welding
  • Repulsive transition: using high current
    with carbon dioxide arc welding etc.

Question 1.11 Characteristics of short circuit transition type

1. Welding by short-circuit period of wire and base material
2. Used for thin plates of 6 [mm] or less
3. Used for small current MAG welding

Question 1.12 Polarity of MAG welding

• In principle, the positive electrode is the wire side,
  the negative electrode is connected to the workpiece

Question 1.13 Characteristics of joints in semiautomatic arc welding

1. Weld metal: part formed from welding wire and base metal
2. Bond part: Boundary part between weld metal and base metal
3. Heat affected zone: Base metal part
   whose structure has changed due to welding heat

Question 1.14 Effect of residual stress

• Residual stress: an example of a large number of defects in welding
• Residual stress and deformation
  • Occurs due to rapid heating and quenching in local heating due to welding
  • Residual stress is generated inside welded part, weld deformation is visible

Question 1.15 Rust prevention from the atmosphere against weld metal

1. Selection and use of shielding gas
2. Selection and use of wire

Question 1.16 Automatic control in semi-automatic welding

1. Partial automatic release of shielding gas
2. Automatic feeding of wire etc.
3. Maintenance of arc length
4. Voltage control

Question 1.17 Advantages of semi-automatic arc welding for hand welding

1. High speed welding
2. In principle the penetration is large
3. No need for sticks
4. Easy acquisition of technology

Note

1. Automatic delivery of wires etc. according to current
2. Maintenance of arc length
3. Automatic release of some shielding gas
4. Reduction of slag

Question 1.18 Droplets after gas shield arc welding method

1. Spray transfer type
2. Short circuit transition type
3. Globular transfer type

Question 1.19 Characteristics of short circuit transition formula

1. A little penetration
2. Good bead
3. Good thin plate and vertical welding

Note

1. Can start short-circuit welding
2. Automatic control of arc length
3. Partial shielding gas can be released automatically