define flux shielded metal arc welding

Flux Shielded Metal Welding

 

Flux Shielded Metal

It is the arc welding process wherein coalescence is produced by heating the w/p with an fsmw electric arc set up between a flux coated electrode and the w/p.

The flux covering decomposes due to arc heat and performs many functions like arc stability weld metal protection etc.

Electrons liberated from the cathode move towards the anode and the arc accelerated. When they strike the anode at high velocity, a large amount of heat is generated.

(Heat required for welding is obtained from the arc struck between a coated electrode and the w/p). The arc temperature and thus the arc heat can be increased or decreased by employing a higher or lower arc current.

The arc melts the electrode end and the job. Material droplets are transferred from the electrode to the job, through the arc and are deposited along the joint to be welded.

The flux coating melts, produces a gaseous shield and slag to prevent atmospheric contamination of molten weld metal.

Flux Shielded Metal Construction:

 

Before welding, the edges of the workpieces are suitably prepared. The edges and the area adjoining them are cleared of all the scale, rust, dust, etc. either chemically or mechanically, using a cure brush grinding wheel, etc.

The workpiece to be welded arc is positioned and spaced concerning each other and held in a fixture.

Welding leads are properly connected to the power source and the workpiece power source is switched on and a suitable welding current is set. The electrode is gripped in the holder and the operator is ready for the weld. Before welding on the actual structure, it is always better to try on a scrap piece to ascertain the optimum current.

Flux Shielded Metal Working:

In manual metal are welding arc between the electrode and the w/p is generally stuck either by momentarily touching by scratching the electrode on the job in the arc of the circle.

Once the arc has been established and the arc length adjusted, the electrode is inclined to an angle of approximately 20 with the vertical. To achieve a comparatively deeper penetration electrode angle with the vertical is further reduced. The electrode is progressed along the joint at a constant speed. This is necessary to maintain a constant arc gap. The bead width can be increased by employing higher arc current, lower arc travel speed.

Flux Shielded MetalAdvantage :

                       1)    Arc welding is the simplest of all welding processes.

                       2)    The equipment is portable and the cost is fairly low.

                       3)    A big range of metals and their alloys be welded.

                       4)    Welding can be carried out at any position with the welding quality.

Flux Shielded Metal Limitations

1)    Because of the limited length of each electron and brittle flux coating its mechanization is difficult.

2)    The process uses a stick electrode and thus it is slow as compared to MIG welding.

3)    Because of the flux coated electrode, the chances of slag entrapment and other related defects are more as compared to Mig or tig welding.

 Flux Shielded Metal Application

a)    Air receiver, tank, boiler.

b)    Shipbuilding.

c)     Pipe and Penstock jointly.

d)    Building and bridge construction.

e)     Automobile and Aircraft industry etc.