Welding is vital to many industries, from skyscraper construction to car manufacturing. And among the various welding techniques available, MMA welding or Manual Metal Arc Welding stands out for its versatility and efficiency.

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Join us as our industrial welding professionals in Quebec present MMA welding (also called stick welding), explaining how it works, its benefits, and why it remains the technique of choice for professionals and hobbyists worldwide.

MMA welding definition

Welding dates back to ancient times, and welding techniques have been constantly refined and adapted over the centuries according to the changing needs of industry. MMA welding occupies a prominent place among the many welding techniques that exist today.

MMA stands for &#;Manual Metal Arc&#;. As the name suggests, this is a manual welding technique that relies on an electric arc to fuse metals. &#;Manual&#; refers to the fact that the welder will guide the electrode by hand, &#;Metal&#; refers to the base material used, and &#;Arc&#; refers to the electrical phenomenon that generates the heat required to fuse the metals.

Examples of MMA welding projects

• Pipeline construction: MMA welding is often used to join sections of pipe with watertight, pressure-resistant welds.
• Agricultural machinery repair: Agricultural equipment is often subjected to hard use. MMA welding is a good choice for repairing these tools, as it produces exceptionally sturdy welds.
• Metal furniture manufacturing: MMA welding is used to create sturdy, attractive furniture or every kind, from chairs to tables.
• Shipbuilding: In shipyards, trained professionals use MMA welding to join large sections of ship hulls and other marine structures.

How does MMA welding work?

MMA stick welding involves a symphony of elements working in concert to create a strong metallic bond. To really understand how it works, let&#;s break down the process, step by step.

Creating the arc

It all starts with the electric arc. When the electrode is brought close to the workpiece and a current is applied, it creates a nearly complete circuit. By moving the electrode slightly away from the workpiece, a gap is formed, where the electric arc appears. This spark generates a tremendous amount of heat, which melts the metal on contact.

Role of the coated electrode

The electrode plays a dual role in this process. First, it acts as a conduit for the current, allowing the electric arc to form. Second, as it melts, it provides the filler metal needed to form the weld. But that&#;s not all: the electrode coating is crucial. As it melts, it generates gases that surround the weld zone, creating a protective atmosphere. This contributes to the formation of a layer of slag on the weld, which can be removed after cooling.

Protection against oxidation and contamination

It is important to protect the weld, otherwise the molten metal will be exposed to oxygen in the air, which could lead to rapid oxidation and compromise weld quality. Other airborne contaminants, such as nitrogen, can also affect the weld. The protective atmosphere generated by the electrode coating prevents these harmful elements from coming into contact with the molten metal, ensuring a clean, strong and long-lasting weld.

Advantages of MMA welding

Despite the emergence of new welding technologies and techniques (such as MIG/MAG welding and laser welding), MMA welding remains a preferred choice for many professionals. But what makes this process so attractive? Here are some of the major advantages of MMA welding.

Versatility

One of the major advantages of MMA welding is its versatility. It can be used on a variety of metals, from common steels to more specialized alloys. Whether you&#;re working on mild steel, stainless steel, cast iron or even aluminum, MMA welding will do the job well. If you need help with projects that involve working with different types of materials, contact us!

The MMA "Stick" Welding Process - your questions answered

What is MMA Welding?

The acronym MMA (or MMAW) stands for Manual Metal Arc Welding. &#;Manual&#; refers to the fact that the MMA process requires the operator to apply filler metal (in contrast to MIG &#;semi-automatic&#; welding where the machine feeds the filler metal into the weld). &#;Metal&#; refers to the fact that the filler metal itself (the stick electrode) is used to conduct the welding current to the job. MMA welding is commonly known as &#;stick-electrode&#; or &#;arc&#; welding.

The MMA process involves the electrode being touched on the job to ignite the arc. The electrode is held in the electrode holder and must be continually replaced as it is consumed. The electrode consists of a metal core, which is the filler metal, covered by a flux coating which shields the weld and prevents it from oxidising. During welding the flux forms into a slag coving the weld which is chipped off after the weld has formed.

What are the Advantages of MMA Stick Welding?

MMA welding offers several advantages over alternative welding processes. Primarily it has a greater capacity than MIG welding, or in other words it can weld heavier materials with the same amperage output. For this reason small, portable MMA inverter welders like Weldforce welding machines by Weldclass, have the capacity to weld with up to 4mm electrodes, making them suitable for a vast range of applications and material thicknesses without the complication of shielding gas or wire feeding.

Thanks to inverter technology, MMA is also a highly portable process and is often used for site and field work.

Also, MMA welding is typically more &#;forgiving&#; than MIG or TIG when welding rusty or dirty materials, which makes it ideal for maintenance applications.

What are the Disadvantages of MMA Stick Welding?

Welding thin materials whilst avoiding &#;blow-through&#; can be tricky with the MMA process. This is easier with inverter welding machines like the Weldforce range from Weldclass because the arc is so stable and the output can be very finely adjusted.

MMA/Stick welding is slower than MIG welding, due to the need to replace electrodes and chip slag. For this reason, MIG is a more popular choice for production work. 

What is the correct Polarity when MMA/Stick welding?

Polarity refers to the direction of current flow when welding. 

Some electrodes types and brands may operate best on DC+ polarity, others are better run on DC-, and many electrodes run either way with very little difference. Polarity is typically less critical when stick welding.

DC+ (also known as; DCEP, or direct current electrode positive)
Work lead connected to the positive (+) terminal
Earth lead connected to the negative (-) terminal
This typically results in deeper weld penetration, with more "heat" directed into the job.

DC- (also known as; DCEN, or direct current electrode negative)
Work lead connected to the negative (-) terminal
Earth lead connected to the positive (+) terminal
This typically results in faster deposition rate (melt-off), with more "heat" directed to the electrode. 

It is recommended to check the manufacturer&#;s instructions or experiment on scrap metal to find the ideal polarity for each type of electrode and application.

Material Thickness vs Electrode Size vs Amps

Because of the many variables in any given application, there is no single formula to say "for X thickness you need X amps". The factors that influence this are;

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Type of electrode/rod
Type of weld joint: Corner, butt, is the joined bevelled or square, etc
Weld position: Flat, vertical, overhead, etc
Technique: Single or multi-pass, joint one side or both sides, etc
Required strength of the weld joint (which will influence whether less or more penetration is acceptable)
Etc

However, here's a rough guide for welding of mild steel

Assuming:
Single sided butt joint, with a single weld pass.
Using general-purpose ( series) or low-hydrogen ( & series) electrodes.

Rule-of-thumb:
For approx' 2mm to 6mm material, chose a welding rod size (diameter) that is one step down from the material thickness.
You can typically use a rod diameter down to half the thickness of the base metal with good results. If the rod is smaller than that, you may still be able to weld it, but the penetration may be less than satisfactory.

Steel
 Thickness 

 Suggested 
Electrode
Size

Amps
Required

1-2mm

1.6-2.0mm

40-60A

2-4mm

2.5/2.6mm

60-110A

4-6mm

3.2mm

90-140A

5-10mm

4.0mm

130-190A 

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The benefits of twin-coated electrodes

Why you will never get a good weld with a bad earth clamp

While all care has been taken, Weldclass accepts no responsibility for any inaccuracies, errors or omissions in this information or links and attachments. Any comments, suggestions & recommendations are of a general nature only and may not apply to certain applications. It is the sole responsibility of the user and/or operator to select the appropriate product for their intended purpose and to ensure that the product selected is capable of performing correctly and safely in the intended application. E.&O.E.

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