GMAW Aluminum

Question 1

Is aluminum hard to weld?

Answer 1

No. Aluminum has a lower melting point, thermal conductivity is 5x greater than steel, and oxide on surface melts at a higher temp than base metal.

Question 2

What processes are used to weld aluminum?

Answer 2

GTAW (thin parts) and GMAW (thicker parts).

OFC and SMAW are possible but very rare. (FCAW - NO)

Question 3

What modes of transfer are used for GMAW of aluminum?

Answer 3

Spray or Pulsed Spray. (Short circuit would be too cold).

Question 4

What type of power source is used for GMAW aluminum?

Answer 4

Normally CV (CC can be used) because amperage will fluctuate to control arc length.

Question 5

What type of current/polarity is used?

Answer 5

DCEP (Reverse polarity)

Question 6

Is the arc control used on a CV machine for GMAW aluminum?

Answer 6

No (inductance only applies to Short Circuit transfer)

Question 7

What shielding gas is used?

Answer 7

100% Argon.

Helium, or mixtures of argon and helium can be used.

Question 8

What should the gas flow rate be set at?

Answer 8

25-40 CFH

Question 9

What type of welding feeders are used?

Answer 9

Push/pull systems or spool guns.

Question 10

Should I push or pull travel be used?

Answer 10

Only A push (forehand) should be used. Arc provides cleaning action.

Question 11

What oscillation techniques are used?

Answer 11

None or back and forth. (Weaves are not recommend due to lack of cleaning action)

Question 12

What position can aluminum be welded in?

Answer 12

All positions (with spray transfer) High thermal conductivity causes puddle to solidify more quickly.

Question 13

How is a weld terminated?

Answer 13

Double-back to fill the crater. (Crater crack will form in an unfilled crater)

Question 14

What is an alloy?

Answer 14

Mixture of metals like

1. Aluminum
2. Copper
3. Manganese
4. Silicon
5. Magnesium
6. Silicon and magnesium
7. Zinc
8. Other elements

Question 15

Are all alloys weldable?

Answer 15

No, alloys 2024 and 7075 are not weldable.

Question 16

What should be considered When selecting a filler metal?

Answer 16

W - easily welding
S - strength
D - ductility
C - corrosion resistance
T - service at elevated temperatures
M - color match

Question 17

How is aluminum prepared for welding?

Answer 17

Must be clean via stainless steel wire brush, acids, saying discs, die grinder and Burr. (Often cut and shaped with carbide tools)