How to Weld Aluminum

Welding Aluminum

Aluminum welding, commonly used in aerospace for its lightweight and resistance to corrosion can be difficult to master. Midwest Metal Products uses two different methods to weld aluminum, TIG Welding and MIG Welding. Learn more about proper tools, safety, methods, techniques, and issues involved with aluminum welding below.

Preparing to Weld Aluminum

Tools Needed:

  • Aluminum welding tools. Read below to learn more about the two commonly used methods for welding aluminum.
  • Stainless steel brush
  • Metal workbench
  • Clamps to hold metal in place
  • Safety Equipment

Proper Safety Equipment:

  • Insulated, fireproof welding gloves
  • Auto-tinting welding helmet
  • Long sleeve cotton shirt. TIG Welding and other processes produce UV radiation that can burn the skin.
  • Fire extinguisher

Clean the Aluminum

It’s extremely important to clean the aluminum prior to the initial weld. Aluminum oxide and hydrocarbon contamination can build up on the outside of aluminum inhibiting penetration of the weld, because oxide melts at a much higher temperature than aluminum. It’s a good idea to clean all aluminum before welding, even brand new aluminum. Begin by spraying the metal with acetone and rinsing with water. When the metal is dry, scrub the aluminum with a stainless steel brush in a single direction.

Signs aluminum is contaminated with oxide or hydrocarbon:

  • The metal burns or distorts when welding.
  • The weld filler won’t blend into the puddle.
  • The aluminum appears to have surface tension.
  • The two pieces of aluminum will not weld together.

Clean the Filler Rod

A dirty filler rod can easily contaminate the weld. Use an abrasive cleaning pad to ensure that the rod is free of contaminants.

Welding Aluminum Methods

TIG Welding: A TIG Welder, or Tungsten Inert Gas Welder, also known as a GTAW (Gas Tungsten Arc Welder), is one of the most popular methods for welding aluminum and other thin metals. The TIG welding process uses a long tungsten rod or electrode and an inert shielding gas of argon to produce the weld.

What You’ll Need:

  • Tungsten Inert Gas welder
  • Aluminum filler rod
  • Argon gas

MIG Welding: A MIG (Metal Inert Gas) Welder is another type of arc welder used to weld aluminum. The MIG Welder, differs from the TIG Welder because it uses metal welding wiring continuously fed through a welding run to burn and fuse two metals together.

What You’ll Need:

  • MIG welding machine
  • Spool gun
  • Shielding gas (argon)
  • Aluminum filler
  • Non-metallic liners
  • Drive rolls

Welding Techniques

Welding Aluminum

TIG Welding: Begin by preheating the aluminum prior to welding to prevent cracking during the welding process. Hold the torch appropriately by bracing your hand against the table and moving slowly. When you’re ready to weld, fit the two pieces of aluminum together as tightly as possible and secure the metal with a clamp. Once the amperage on the TIG machine is set, begin the weld. When the puddle forms, add the filler rod until the joint is filled and move to the next area to weld. Keep the tungsten about 1/4” from the puddle at all times and move at a slow, even pace to avoid gaps in the weld. Remember to always hold the torch at a 90 degree angle while pushing the torch away from, not towards you.

MIG Welding: When beginning a MIG weld, begin by connecting the spool gun to the positive stud on the welding machine. After the aluminum is clean and preheated, use a 10 to 15 degree angle to push the tip of the spool gun forward along the joint. Continue the motion until the joint is filled. Remember to always hold the torch at a 90 degree angle while pushing the torch away from, not towards you.

Common Problems/Troubleshooting

Contaminated Tungsten (TIG): Contamination occurs when the tungsten from a TIG welder touches the weld pool or the filler. When this happens, the arc of the weld becomes unstable and the quality of the weld decreases. To fix this, remove the tungsten, lay the tungsten on a flat surface and remove the end where it is contaminated. Reinstall the tungsten to the welder, change the polarity to DCEP (direct current electrode positive), practice an arc on scrap metal, return to AC high and begin welding again.

Burn-throughs: A burn-through occurs when the base material becomes overheated. To prevent this, increase travel speed, making shorter welds or reduce the amount of gas used.

Dirty Welds: To avoid contaminating a weld push the weld away rather than dragging or pulling the weld towards yourself. Be sure to clean the aluminum properly before welding.

Wire Burns (MIG): To avoid wire burns near the contact tip throughout the weld, keep an appropriate distance between the weld and the tip. Also, ensure you are using the correct tip sizes, liner, and wire for the particular job.

For questions concerning aluminum welding contact our experts at Midwest Metal Products.

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