Electric Resistance Welding

Electric resistance welding - the formation of permanent connection of metals by heating them to passing an electric current and the plastic deformation zone of the connection force of compression. Important role in the resistance welding is the electrical resistance zone of connection (for example, it determines the amount of heat) and gives it another name - the electric resistance welding.

Standard notation
ERW - Electric Resistance Welding - electric resistance welding

The essence of the process
Resistance welding is a thermomechanical (combined) welding method in which to get the permanent connection of parts used by two physical processes - heat flowing current and pressure. According to the Joule-Lenz's law, the amount of heat released in the conductor (base metal) during the passage through it of an electric current I for time t:

Q = I 2 · R · t ,

where R - the resistance of the path of electric current.

Used in the welding heat is released when the current flows in the welded blanks, contact (the joint area) between them, as well as in contact with the electrodes of blanks. As shown by the above formula, the effective heat of welding is provided primarily for large values ​​of the current flow (up to thousands and tens of thousands of amperes). The greatest heating occurs in the contact between the parts due to its higher resistance, as well as adjacent to the contact zone of the metal. In the process of welding and joining products into one contact resistance decreases.

When properly flowing during the heating surfaces of workpieces, adjacent to the electrodes is negligible, since the contacts between them have relatively little resistance because of the high electrical conductivity and softness of the metal electrode and the electrodes themselves are cooled by water.

Types of welding
The main types of welding, depending on the shape of the welded joint:

• spot welding - a one-point, point to point, multipoint;
• projection welding ;
• seam welding - continuous, intermittent, steps;
• butt welding - resistance and reflow;
• seam-butt welding;
• relief-spot welding;
• welding by the method of Ignatieff.

Benefits
Resistance welding is widespread in industrial production due to the following benefits:

• performance through the use of large electric power (while welding a junction or point of up to 0.02-1);
• high and stable quality of welded joints;
• low qualifications welder;
• opportunities for mechanization and automation of the process (welding machines or welding parts can be relatively easily integrated into continuous assembly and welding lines);
• low consumption of auxiliary materials (air, water), lack of demand for consumable welding materials (gas, filler wire, flux, etc.);
• high environmental process.

Welding technology:

manual arc welding semi-automatic welding argon arc welding machine welding electroslag welding plasma welding laser welding electron beam welding

gas welding resistance welding spot welding seam welding projection welding butt welding welding underwater welding in space