MMA Inverter Electrode Welders

Coated electrode welding is certainly the most widespread among those who do not require particular productivity performance, not only for the reduced purchase cost compared to other more professional models, but also for the ease of use. Features that unfortunately will be detrimental to the aesthetics of the welding due to the production of slag due to the absence of the protective gas.

Principles of MMA electrode welding

MMA coated electrode welding uses the heat that is generated by an arc that strikes between the electrode and the piece to be welded. It is the most popular technology for manual electric arc welding.

Thanks to this procedure it is possible to weld all ferrous metals such as iron, cast iron, steel and stainless steel; with other metals it is advisable to use other technologies. To work correctly it is necessary to interrupt the welding to replace the electrode if the latter is worn, moreover it is necessary to remove the slag after each single pass.

The electrode consists of a cylindrical metal core with the function of filler metal and a coating with the following functions:

• protection of the molten bath from atmospheric agents
• purification of the molten bath
• addition of alloying elements to the welded joint
• stabilization of the electric arc

The core can have different diameters and lengths and must correspond to the material to be welded. The type of coating is variable depending on the specifications of the joint and the welding positions. For each type of electrode, the polarity and current intensity indications must be respected during welding.

Inverter electrode welding machine which is the most suitable?

To understand which electrode welding machine model is right for you, first of all you need to know the type of use you will make of it, what you will have to weld and how often you will use it .. already from this information you can understand if you need to buy a hobby-type welding machine (for sporadic use), or semi-professional / professional type for greater performance and reliability. Keep in mind that obviously, for a professional welding machine, the cost will be higher than the basic models for DIY.

The Electrodes

There are various types of electrodes:

• Rutile RT electrode
• Basic Electrode BS
• Electrode in stainless steel SS
• Cast iron electrode Ci
• Aluminum electrode AL
• CE Cellulose Electrode
• Acid electrode

Depending on the type of welding machine used and the material to be welded, the correct electrode must be chosen, suitable for the work to be performed.

Characteristics of the electrodes

Traditional Welder or Inverter Welder

There are two main types of electrode welders: the traditional electromechanical ones, and the Electronic Inverter Welders.

The main difference is in the power supply system.
The traditional welding machine uses a common, very heavy transformer that supplies alternating current AC.
Inverter welding machines, on the other hand, use an electronic circuit that works on the frequency providing a current very similar to direct DC.

In addition to being lighter, the inverter welders allow an easier ignition of the electrode, and have a lower cost. On the other hand, they are more prone to electronic failures.

Table for the correct welding machine / electrode combination

The diameter of the electrode

Furthermore, the diameter of the electrode that must be used in welding must be taken into consideration in order to set an adequate current value according to the table below:

MMA welding of materials

If you have to work with steel of an easily recognizable composition, rutile electrodes can be used, due to the greater ease of ignition, welding and the good aesthetics of the bead.

Welding steels with medium / high carbon content (> 0.25%) can cause the formation of structural defects. In order to obtain a high quality of welding and a good resistance to breaking, the electrode process is recommended especially for the welding of joints with medium-large thickness and using basic electrodes.

Cellulosic electrodes are used to weld steel pipes, which provide high penetration and good workability of the electrode. Chamfering is always recommended, with a sufficient chamfer angle to guarantee an almost complete introduction of the electrode into the bevel.

For special materials such as stainless steels, cast iron and aluminum and its alloys, specific electrodes are used for the treated material:

• Stainless steels are welded in direct current with reverse polarity; specific electrodes are used which differ in the metallurgical composition of the material to be welded (presence of chromium (Cr) or nickel (Ni) in variable percentages).
• Aluminum and light alloys are welded in direct current with reverse polarity. The welding machine must have a rather high engagement dynamics to guarantee the ignition of the electrode. Also in this case special electrodes are used, which differ in the metallurgical composition of the piece to be welded (presence of magnesium (Mg) and silicon (Si) in variable percentages).
• Cast iron is welded in direct current with reverse polarity; most of the mechanical parts and cast iron structures are obtained by casting, so welding is used to correct any casting defects and for repairs. Special electrodes are used and the base material must be adequately heated before use.

Semi-professional Electrode Welders for DIY

For the demanding hobbyist, better performance than hobbyists at a low price. Supplied with or without accessories case.