Large arc welding machines are mounted on wheels; these are very powerful devices for professional construction sites. Amateur welders use portable devices that make remarkable achievements. Arc welding is quite easy to master for a handyman.
These stations work according to the principle of the electric arc, resulting from the passage of electricity in the air, which provides a strong heat and a bright light. To weld, the arc passes between the welding rod (electrode) and the part itself. The heat released leads to the melting of the filler metal and the part. The electric arc produces a temperature of the order of 4000 to 4500° C. It is therefore a welding of very high quality.
The welding machine is especially designed for welding mild steel, stainless steel and cast iron. The electrodes are of a metal of the same nature as the welded metal; the two metal parts are bonded by fusion (autogenous welding). Arc welding makes it possible to obtain very good results and to work quickly. The equipment is quite expensive, it is reserved for those who regularly work the metals.
Characteristics of the welding machine
The welding machine consists of a transformer connected to a 220 V single-phase power supply (or 380 V for the most powerful devices).
This transformer lowers the voltage up to 40 or 50 V (starting voltage), which increases the intensity and triggers the formation of the arc. Each welding machine is therefore characterized by this vacuum voltage and the welding current. The latter, indicated in amperes, goes from 30 to 120 A for a light post, and from 60 to 180 A for the most powerful ones.
The power of the device determines the diameter of the electrodes that can be used.
It varies from 1.6 to 2.5 mm for a light device, and 1.6 to 4 mm for the most powerful. The manufacturer usually indicates the number of electrodes per hour. The welding machine is provided with a carrying handle and a intensity adjustment wheel welding (shunt steering wheel).
The on / off switch has an indicator light that turns off when the thermostat trips in case of overheating. The thermal reclosing is done automatically. A plaque is affixed to the post; it indicates the choice of the diameter of the electrode and the intensity of welding for each thickness of parts to be welded. The electrodes are carried by a clamp connected to a cable. The workpiece is energized by the earth clamp.
The device comes with a safelight mask; its use is obligatory. The other accessories are a hammer to prick and an wire brush for cleaning welding beads.
Electric welding uses metal electrodes encased in a sheath to the composite coating. Its function is to direct the arc punctually and to facilitate priming. The cinder resulting, removes impurities from the metal to be welded. Fans generally use anti-glare electrodes with very low priming voltage.
They facilitate the welding because it is enough to put them on the sheet so that the advance is done automatically. When welding large thicknesses, the weld bead is made in several passes. After completion of the welding, the electrode leaves a crust on the cord (dairy) must be removed with a prick hammer.
The welding machines are double insulated; however, it is advisable to use them with a grounding plug. Never perform a welding, even if brief, without using the specially designed mask; you risk serious eye damage. It is better to work alone.
Those present must also wear a mask because the light of the bow is very violent. Also beware of reflected light radiation. Never work near flammable materials (products stored in the workshop or clothing).
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