Design Brief: To understand the various types of welding processes.

Context: Safety is first in the workshop. Read and understand all of the safety rules before using any tool or machine.

Possible Solutions: Have instructor demonstrate (mandatory) the tool first. Have another student demonstrate the tool. Read the manual that comes with the tool (mandatory). Ensure that you have been certified “competent” by the instructor before you use the tool (mandatory).

Detail Design: The following are the common types of welding processes:

The most popular processes are Gas Metal Arc Welding (GMAW), sometimes called MIG welding and Gas Tungsten Arc Welding (GTAW) sometimes referred to as TIG welding. A third process, Shielded Metal Arc Welding (SMAW) or stick welding.

SMAW — Shielded Metal Arc Welding or Stick Welding

SMAW is an electric arc welding process in which heat for welding is generated by an electric arc between a covered metal electrode & the base metal. The electrode coating provides shielding. The welding equipment for this process is currently the most inexpensive of the methods described here. However, electrodes do create some inefficiency, such as stub loss & a slag coating, which must be removed.

GTAW — Gas Tungsten Arc Welding or Tig Welding

Tig Welding is easily performed on a variety of metals. It generally requires little or no post weld finishing. It is an electric welding process in which heat for welding is generated by an electric arc between the end of a non-consumable tungsten electrode & the base metal. Filler metal may be added, if necessary. An inert shielding gas supplies shielding for the arc. (Inert gas creates a protective atmosphere around the welding in process).

GMAW — Gas Metal Arc Welding or Mig Welding

Gas metal arc welding is quick & easy on thin-gauge metal as well as heavy plate. It generally calls for little post weld cleanup. GMAW is an electric arc welding process where heat is produced by an arc between a continuously fed filler metal electrode & the base metal. Shielding is obtained from an externally supplied gas or gas mixture. The two most common types of GMAW are:

• Short Circuit Transfer — The arc is broken or short circuited with each drop of metal & restarted. Short circuiting transfer is not used with aluminum welding.
• Spray Transfer — Metal is transferred across the arc creating a continuous spray of fine droplets of metal. These droplets are projected down to the base metal.

Materials: welder, electrodes, leathers (jacket and gloves), shielded hood.

Commissioning: Were you successful in this project when you tried it out?

Evaluation: Did this project work as you expected it to?

Reflection: Did you enjoy this project? What were you most proud of? What would you do differently next time?