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What is Shielded Metal Arc Welding (SMAW)?


Metal Welding

Shielded metal arc welding, commonly abbreviated as SMAW, is a fusion arc welding process. Shielded metal arc welding is one of the oldest of the modern welding processes that is still quite popular. When determining if shielded metal arc welding is the right welding process for a project, it is necessary to know the fundamentals of the process, what metals it is capable of welding, and its advantages and limitations.

What Does Shielded Metal Arc Welding Mean?

As a fusion arc welding process SMAW coalesces two or more metals together. This coalescence creates the metallurgical bonds needed to form a strong weld. Arc welding means that SMAW uses an electric arc to heat the metal above its melting temperature to create this coalescence. The arc is created between a consumable electrode rod and a workpiece. This electrode rod is sometimes called a “stick electrode” which is why SMAW is often referred to as “stick welding”. The SMAW process is also “shielded”. This means that the weld pool is shielded from the atmosphere through the use of a flux that is coated directly onto the consumable stick electrode.

How Does Shielded Metal Arc Welding Work?

To begin welding with the SMAW process, first a SMAW welding power source must be turned on. This power source provides the energy necessary to create an electric arc which can be used to melt the metal being welded. Attached to the power source is an electrode holder and a work clamp. The work clamp is hooked to a conductive surface holding the workpiece or to the workpiece itself. Then a stick electrode is put in the holder.

To initiate the electric arc, the rod is lightly scratched on the surface of the desired weld area. The electric arc begins to melt both the workpiece and the rod, the latter of which provides additional metal for the weld. The flux on the rod also begins to melt with the rod itself, emitting gases, liquids, and solids around the molten weld pool that prevent the metal from oxidizing and becoming porous.

Once the weld is finished and it begins to cool, a slag film is formed over top from the flux that was on the electrode. It is critical that the slag is removed prior to subsequent welding passes or coating.

What Metals can be Welded Using Shielded Metal Arc Welding?

SMAW is somewhat limited in the metals that it can be used to weld. Metals that can be welded very well with SMAW are carbon steel, tool steel, cast iron. Metals that have okay SMAW weld characteristics include stainless steel, copper, and nickel. Other non-ferrous metal SMAW welding is not popular. Aluminum is sometimes welded using SMAW, but it is not recommended.

Advantages of SMAW

Some of the advantages of using shielded metal arc welding include:

  • Low cost
  • Great for outdoor and field welding
  • Great for dirtier metals, although care should be taken to clean any metal being welded as much as reasonably possible

Limitations of SMAW

Shielded metal arc welding has some disadvantages, including:

  • Somewhat slow welding process
  • Inefficient deposition of consumable rod use (stubs need to be thrown out)
  • High amounts of spatter
  • Requires the removal of slag

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