Shielded Metal Arc Welding: Process and Applications

SMAW welding is one of the oldest welding processes, being used commercially since the early 1900s. Whilst the basic principle has remained the same, the alloys used and resulting welds have progressed significantly.

In this article, we’ll take a look at how SMAW welding works, what makes it useful, and what some common applications of it are.

What is SMAW Welding?

SMAW welding uses an electrical arc between a consumable metal rod (electrode) and the workpiece to melt both into a fusion weld.

The electrodes are coated with a flux in the form of a hardened powder. This flux burns off as the rod is consumed, shielding the weld pool from contamination and oxidation.

SMAW is known by a few other names, such as MMA (manual metal arc), stick welding, or sometimes just arc welding. It is one of the oldest and simplest forms of welding, but it can produce very high-quality joints.

How the SMAW Process Works

With the earth clamp attached to the workpiece, an arc is struck between the end of the rod, which acts as an electrode, and the workpiece. The intense heat from the arc melts both the base material and the rod, allowing them to create a fusion weld.

The level of heat input is dictated by the current setting of the welding set, whilst the arc length determines the voltage. Maintaining the correct rod angle, travel speed and arc length is crucial in achieving a weld with adequate penetration and profile.

Once a weld is complete, the burnt flux leaves a deposit on top of the weld bead, colloquially known as slag. This is usually chipped or scraped off, though some electrode types allow easier removal of slag than others.

Electrodes come in a variety of diameters, depending on the size of the weld required. Larger rods need higher currents to weld properly; the welding set output is often the limiting factor on which rod sizes can be used.

Common Electrodes and Their Uses

All manners of SMAW electrodes are available, including those used for aluminum, stainless steel and more. These are some of the most commonly used electrodes:

• E6013 – These are general purpose, easy to use mild steel electrodes with reasonable strength and smooth running
• E7018 – Sometimes referred to as “low hydrogen” electrodes, these are common in structural steel and high strength applications
• E6010 – These rods give deep penetration and produce quick setting slag, perfect for positional welding such as overhead and vertical down – often used by pipeline welders for root passes
• E308L – A stainless steel rod that is easy to strike and run, which can be used in many positions. 308

Advantages and Limitations of SMAW Welding

No one welding process is perfect for all situations and jobs, in some cases, only a certain method will work, and in less demanding situations, it can be down to personal preference or availability.

Advantages of SMAW Welding

• Versatile materials – almost all weldable metals can be welded with SMAW, even cast-iron repair rods, hard facing, and more
• No gas needed – this reduces the upfront cost of the process and means less equipment to transport and maintain.
• Outdoor suitable – processes that use shielding gas, such as solid wire GMAW or TIG, are not the best for use in outdoor environments, where wind can affect the shielding. SMAW welding does not suffer from this problem

Disadvantages of SMAW Welding

• Lower deposition rate – needing to change your rod frequently, and chip off slag, slows down the process compared to GMAW
• Harder to learn – Maintaining arc distance and striking the arc can be difficult for new welders, as can maintaining rod angle as it is consumed. GMAW welding is generally considered to be much easier to learn
• Fume – the burning of flux creates more smoke and fumes than other types of welding; some types of flux smoke can be quite harmful

Industrial Applications of SMAW Welding

Whilst SMAW has been replaced with GMAW in many mass production environments, SMAW still has a place in industry.

• Construction and structural steelwork – Structural welding on steelwork, reinforcing bars, and parts such as tie bars are often done on site using GMAW, as it’s more portable and less susceptible to wind
• Pipeline – Other than fully automated systems, GMAW is still the predominant method for welding oil and gas pipelines in the field
• Agricultural – For repairs and maintenance on agricultural equipment, GMAW offers versatility and ease of use
• Mining repairs – For repairing broken machinery or equipment in less-than-ideal conditions, GMAW is the ideal solution

Metals Supply for Your Welding Project

Whether you’re using SMAW, GMAW or any type of welding, you’ll need quality metal supplies on time and at a good price.

Metals Supermarkets supply everything from mild steel to aluminum, stainless steel and more, all with a cost-effective cut to length service. Find your nearest Metals Supermarket store here.