7
Welding
7.1 OBJECTIVES
1.) become familiar with basic welding operations
2.) perform basic calculations for fusion welding processes
3.) perform basic welding operations
7.2 MATERIALS AND EQUIPMENT
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TIG Welder
MIG Welder
Welding specimens
7.3 BACKGROUND
Welding and joining processes are used to bond two different materials together. In the case of
welding, the joint involves bonding the materials together at the atomic level through some
combination of heat and pressure. This lab will introduce you to two of the most common fusion
welding processes, Gas-Metal Arc Welding , GMAW (also known as Metal Inert Gas or MIG),
and Gas Tungsten Arc Welding, GTAW (also known as Tungsten Inert Gas or TIG).
7.4 PROCEDURE
Your lab instructor will demonstrate several welding processes for you. You will be provided
with workpieces and allowed to try the processes yourself. Record all critical variables in the
provided data sheet.
7.5 LAB REPORT REQUIREMENTS
Following the Lab Report Guidelines included in Appendix A of this manual, prepare and
submit your report as a group. In particular, your lab report should include the following:
1.)
Estimate the power and energy requirements for each of the welding operations you
performed
2.)
What are the advantages and disadvantages of the two processes you performed?
Welding Data Sheet:
Welding Process 1 – GMAW (MIG)
Voltage Setting: ________________
Material Being Welded (type and dimensions): ________________
Welding Wire Type and Size: _________________
Shielding Gas and Flow Rate: _____________________
Measure the weld bead of your most successful weld. Sketch the weld bead here with enough
dimensions to estimate the cross-sectional area. Assume that penetration into the metal
converges at 45 deg. angles from the edges of the weld bead (90 degree included angle). What
was the length of your weld? Make notes about the quality of the weld and any variations you
observed as a result of changes to machine settings or welding technique.
Welding Process 2 – GTAW (TIG)
Current Setting: ________________
Material Being Welded (type and dimensions): ________________
Welding Electrode material and tip shape: _________________
Polarity and Current Settings: ____________________________
Shielding Gas and Flow Rate: _____________________
Average current during most successful weld _______________________
Average voltage during most successful weld _______________________
Measure the weld bead of your most successful weld. Sketch the weld bead here with enough
dimensions to estimate the cross-sectional area. Assume that penetration into the metal
converges at 45 deg. angles from the edges of the weld bead (90 degree included angle). What
was the length of your weld? Make notes about the quality of the weld and any variations you
observed as a result of changes to machine settings or welding technique.