FCAW – Flux Core Arc Welding is a type of electric welding process that supplies the filler electrode mechanically to an electric arc formed between the tip of the filler electrode and the parent metal. It is almost similar with GTAW. FCAW uses a heat source from electrical energy. The welding machine converts electricity into a heat source in an electric arc. FCAW has a shield that is used in the welding process, namely flux or powder that is in the core of the welding wire. FCAW welding wire is coiled in a roll. Flux Core Arc Welding also uses another shield in the form of a gas that protects the weld metal from melting.
Based on the type of protection, FCAW welding (Flux Core Arc Welding) is divided into two types, namely Self Shielding and Gas Shielding. Self Shielding FCAW is an FCAW welding process that uses flux. Gas Shielding FCAW is an FCAW welding process that uses flux and additional gas from outside the system or gas from the cylinder. The function of flux and gas protection is to provide gas and liquid slag protection which protects the weld from the atmosphere. This type of FCAW was developed primarily for welding structural steel. The shielding gas most commonly used is carbon dioxide or a mixture of carbon dioxide argon. The most commonly used mixture is 75% Argon 25% Carbon Dioxide. The flux core in the tubular consumption electrode contains more than just flux. They contain a variety of chemicals which when exposed to high welding temperatures produce a shielding gas to protect the arc.
The FCAW process is widely used in construction projects due to its high productivity/welding speed and portability. In contrast to manual types such as SMAW and GTAW, FCAW belongs to the category of semi-automatic or automatic arc welding processes. FCAW welding machines are very attractive because they are portable and generally have good penetration into the base metal. In FCAW welding, windy conditions do not need to be considered so that welding can be carried out outdoors / workshops.
Advantages of FCAW :
- in a closed workshop environment, generally produces welds with better and more consistent mechanical properties, with fewer weld defects than the SMAW or GMAW processes.
- FCAW is preferred for welding thick metals
- high productivity as the operator does not need to stop periodically to pick up new electrodes
- can be done outdoors
- The slag created by the flux is easy to remove.
- Alloying elements can be added to the flux core to create a wider variety of compositions, including some low-alloy metals and stainless steels.
Disadvantages of FCAW :
- Some of the drawbacks are that this process can produce excessive amounts of harmful fumes (making it difficult to see the weld pool).
- Operator skill is a major factor as improper electrode manipulation or machine setting can cause porosity.
- not a low hydrogen process
- may result in poor notch toughness.
- The filler metal used must meet the impact test requirements such as T-1, T-5 and T-8 electrodes. These electrodes generally have a lower hydrogen content and have special chemical requirements to produce more consistent properties.
The difference between FCAW and SMAW lies in the electrodes and shielding gas. SMAW electrodes are in the form of sticks wrapped in Flux, while FCAW is in the form of wire rolls and the flux is inside the wire. For protection SMAW only Flux, while FCAW can use only flux or flux with gas. The FCAW process is essentially the same as the GMAW welding process. it’s just that the main difference is the tubular electrode that contains flux.
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