GMAW Fundamentals: Part 1 of 2 (WDTM3)The learner will examine the fundamentals of GMAW.Author  Craig Schmidt 



Question 1: What does the abbreviation GMAW stand for?
Answer 1: Great Metal Arc Working Answer 2: Gas Material Arc Welding Answer 3: Gas Metal Arc Welding Correct Answer: Gas Metal Arc Welding Feedback: Gas metal arc welding is a welding process that uses an arc between a continuous filler metal electrode and the weld pool. 



Question 2: What is another abbreviation for GMAW ?
Answer 1: MIG Answer 2: WAMG Answer 3: MEG Correct Answer: MIG Feedback: MIG stands for Metal Inert Gas. 



Question 3: The three basic metal transfer modes in GMAW are short circuiting, globular transfer, and spray transfer. What would a fourth one be?
Answer 1: Under arc Answer 2: Hot spray Answer 3: Pulse spray Answer 4: Under arc or hot spray Correct Answer: Pulse spray Feedback: Pulse spray is much like a spray transfer but it has two levels of current: one constant lower background current and a second pulsing current that goes above the “transition current” to spray. Pulse spray also requires a special pulsing power source. 



Question 4: What material thickness is recommended for short circuit transfer?
Answer 1: 2 inch Answer 2: Thin Answer 3: Thick Answer 4: Any thickness Correct Answer: Thin Feedback: Because of the low voltages and currents (amps) used, thin material is best suited for short circuit transfer. 



Question 5: How many short circuits occur per second while welding in short circuit transfer?
Answer 1: 515 Answer 2: 600800 Answer 3: Two Answer 4: 20250 Correct Answer: 20250 Feedback: "Short circuit" is defined as an arcon/arcoff weld cycle. 



Question 6: Buried arc is an offshoot of short circuit. What makes buried arc different from short circuit?
Answer 1: The name Answer 2: The wire and gas used Answer 3: Excessive wire feed speeds (WFS) Answer 4: The machine being used Correct Answer: Excessive wire feed speeds (WFS) Feedback: Buried arc creates short circuits below the surface of the material. 



Question 7: Globular transfer is the least preferred transfer method.
Answer 1: True Answer 2: False Correct Answer: True Feedback: Globular transfer is the least preferred transfer method because of the large amounts of spatter created and the possibilities of weld discontinuities. 



Question 8: Spray transfer requires an argon gas content of at least what percentage?
Answer 1: 75% Answer 2: 50% Answer 3: 90% Answer 4: 80% Correct Answer: 80% 



Question 9: How many times does the electrode contact the material when welding in spray transfer?
Answer 1: 20200 Answer 2: 50100 Answer 3: One Answer 4: 10 Correct Answer: One Feedback: Spray transfer is defined as an open arc (always on). Droplets form and detach across the arc at a rate of hundreds per second and therefore only contact the material once at the arc start. 



Question 10: Spray transfer requires high voltages and high WFS. What positions and thickness of material is spray transfer best suited for?
Answer 1: All positions and all thicknesses Answer 2: Overhead and vertical positions using thin materials Answer 3: Flat and horizontal positions using thicker materials Correct Answer: Flat and horizontal positions using thicker materials Feedback: Because of surface tension and gravity, spray transfer is not suited for overhead or vertical positions. And because of the high voltages and WFS, thin materials are not recommended. 



Question 11: Increasing wire feed speed will increase all except what?
Answer 1: Depth and width of penetration Answer 2: Deposition rate Answer 3: Quality Answer 4: Weld bead size Correct Answer: Quality Feedback: Welding amperage (current) varies with the wire feed speed setting if no other variables are changed. Increasing the current will increase the heat on the wire, producing greater penetration. 



Question 12: What happens when voltage is increased?
Answer 1: The fusion zone increases Answer 2: The weld profile flattens Answer 3: The fusion zone increases and the weld zone flattens Answer 4: It makes no difference Correct Answer: The fusion zone increases and the weld zone flattens Feedback: Welding voltage is directly related to the arc length. Increasing the voltage will heat the base material more, producing a wider, flatter bead profile. 



Question 13: What happens when voltage is decreased?
Answer 1: A narrow weld bead with a high crown is produced Answer 2: The weld profile flattens Answer 3: The fusion zone decreases Answer 4: It makes no difference Correct Answer: A narrow weld bead with a high crown is produced 



Question 14: What two settings dictate the mode of transfer you are in?
Answer 1: There is only one setting: wire feed speed Answer 2: There is only one setting: voltage Answer 3: Power switch and time Answer 4: Wire feed speed and voltage Correct Answer: Wire feed speed and voltage 



Question 15: What material can NOT be welded with GMAW?
Answer 1: Copper Answer 2: Aluminum Answer 3: Stainless steel Answer 4: Titanium Answer 5: Carbon steel Answer 6: Low alloy steel Answer 7: Cardboard Correct Answer: Cardboard Feedback: Carbon steel, highstrength lowalloy steel, stainless steel, aluminum, copper, titanium, and nickel alloys can be welded with GMAW by choosing the appropriate combination of shielding gases, electrodes, and welding variables. 


This workforce product was funded by a grant awarded by the U.S. Department of Labor’s Employment and Training Administration. The product was created by the grantee and does not necessarily reflect the official position of the U.S. Department of Labor. The U.S. Department of Labor makes no guarantees, warranties, or assurances of any kind, express or implied, with respect to such information, including, but not limited to, accuracy of information or its completeness, timeliness, usefulness, adequacy, continued availability, or ownership. Auxiliary aids and services are available upon request to individuals with disabilities. This equal opportunity program is part of a grant from the U.S. Department of Labor equaling $2,999,750.00.