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Chapter 19 PowerPoint Presentation

Chapter 19

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Chapter 19

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  1. Chapter 19 GMAW–Equipment Gas Metal Arc Welding • GMAW Current Selection • GMAW Welding Power Sources • GMAW Equipment • GMAW Welding Wire

  2. Constant-current (CC) power sources have a steep volt-ampere (V-A) curve, while constant-voltage (CV) power sources have a slightly sloping V-A curve.

  3. CV power sources are self-correcting with respect to arc length, which means that arc length remains constant with changes in electrode extension.

  4. GMAW equipment includes a welding gun cable and gun assembly, a wire feeder, shielding gas, and a workpiece lead with a workpiece connection.

  5. Welding gun components include a handle with a conductor tube and trigger, a contact tip, a gas nozzle, a gas diffuser, and an insulator.

  6. Welding guns are available with curved or straight conductor tubes.

  7. The wire feeder may be portable, mounted on the welding machine, or mounted elsewhere to facilitate welding in a large area.

  8. Drive roll grooves can be U-shaped, V-shaped, or knurled depending on the type of welding wire.

  9. The wire outlet guide must be aligned closely with the groove in the drive rolls, without touching it.

  10. Inert gases do not react readily with other materials, making them useful as shielding gases for arc welding.

  11. Different shielding gases produce different weld bead contour and penetration characteristics.

  12. The welding area should be protected with windbreaks to prevent gas drifts.

  13. The American Welding Society (AWS) classification system for carbon steel electrodes consists of a series of letters and numbers.

  14. The American Welding Society (AWS) has developed similar classification systems for metals other than carbon steel.

  15. Welding position and the type of metal to be welded are factors that must be considered when selecting welding wire.