Advantages of SMAW Welding Machine – AC type
- Less expensive equipment and maintenance
- The mass wire and electrode cable can be exchanged, but does not affect the weld result.
- Small flame arc thereby reducing the incidence of porosity in the weld teeth.
Advantages of SMAW Welding Machine – DC type
- The resulting arc of electric flame is stable
- Can use all types of electrodes
- Can be used for welding thin plates.
understanding SMAW welding machine. AC and DC
- Alternating current (AC)
Because there is a change in the direction of the flow of the electric current, it is hot the resulting weld is divided evenly between the welding electrode (50%) and the parent material (50%).
- Directional electric current (DC)
The direction of the flow of electricity is always constant, that is, from the negative pole, so the electrons will move from positive to negative pole. Due to the different parts of the heat generated on the workpiece and electrode, then the rectification of the electric current is divided two ( DCSP/DCEN and DCRP/DCEP )
DCSP (Direct Current Straight Polarity) or DCEN (Direct Current Electrode Negative)
The workpiece is connected to the positive pole and the electrode is connected to the negative pole, so that some of the heat (30%) is absorbed by the electrodes while in the workpiece (70%). The penetration result will be deep. This polishing can be used to weld thick objects
DCRP (Direct Current Reverse Polarity) or DCEP (Direct Current Electrode Positive)
The workpiece is connected to the negative pole, and the electrode is connected to the positive pole. Since the heat of the workpiece is low, this method is good for welding thin plates, as it results in shallow penetration.
A very important part of coated electrode welding is the electrode. The type of electrode used will determine the result of the welding.
- As a welding arc protector from the influence of the atmosphere such as oxygen, nitrogen and air.
- Prevents ionization at the electrode tip.
- Keeping the bow steady
- Produces slag and slag
- As an integral element
- To control the electrode fluid
- To control penetration in welded joints
- To control the profile or welding contour, especially in the welding process that uses filler metal.
The wrapped electrode is a source of weld metal which consists of:
a. The axis of the electrode is a filler metal that melts in an electric arc together with the parent material and then freeze to form seam weld.
b. The electrode envelope (flux) breaks down in the electric arc and generates CO2 gas shield as well as a solid layer, both of which protect the weld seam being formed against the damaging effects of the air around him.
In addition to protecting the weld seam, flux also functions:
- Prevent the formation of metal oxides and nitrides, during the welding process;
- Making protective slag so as to reduce cooling speed, this is intended so that the results of the welds that occur are not brittle and brittle;
- Give special properties to the results of the weld by adding certain substances contained in the membrane;
- Stabilizes the arc and directs the flame so that it is easy to control;
- Helps control the size and frequency of molten metal droplets;
- It is possible to do different welding positions.