SMAW welding machine

SMAW Welding machine : DCEN welding (Direct Current Electrode Negative) or DCEP welding (Direct Current Electrode Positive)

DCEP welding vs DCEN welding

Welding using SMAW machines can use either AC or DC currents. The DC current welding machine has two polarities, namely the DCEN (Direct Current Negative Electrode) and DCEP (Positive Direct Current Electrode) polarity. each of these polarities has different advantages and disadvantages, as well as in its application in the Industrial world. DCEN polarity is also referred to as DCSP (Direct Current Straight Polarity) while DCEP polarity is DCRP (Direct Current Revers Polarity).

Advantages of SMAW Welding Machine – AC type

  1. Less expensive equipment and maintenance
  2. The mass wire and electrode cable can be exchanged, but does not affect the weld result.
  3. Small flame arc thereby reducing the incidence of porosity in the weld teeth.

Advantages of SMAW Welding Machine – DC type

  1. The resulting arc of electric flame is stable
  2. Can use all types of electrodes
  3. Can be used for welding thin plates.

understanding SMAW welding machine. AC and DC

  1. 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%).
  2. 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 welding (Direct Current Straight Polarity) or DCEN welding (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 welding (Direct Current Reverse Polarity) or DCEP welding (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.

DCEN (DCSP) and DCEP (DCRP) Polarity Differences:

DCEN Polarity

  1. The electric arc in stick welding moves from the electrode to the base material so that the collision of electrons is on the base material which results in 2/3 of the heat being in the base material and 1/3 of the heat being on the electrode.
  2. The DCEN polarity results in more melting of the base material than the electrode so that the weld has a deep penetration, so it is good for slow welding, narrow areas and for thick plates.

DCEP Polarity

  1. The electric arc moves from the base material to the electrode and the collision of electrons is at the electrode resulting in 2/3 of the heat being on the electrode and 1/3 of the heat being on the base material.
  2. DCEP polarity results in more melting of the electrode so that the weld has shallow penetration, and is good for welding thin plates with wide weld beads.

SMAW electrodes

A very important part of coated electrode welding is the electrode. The type of electrode used will determine the result of the welding.

Electrode function

  • 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.

Electrodes Parts

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.

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