In arc welding with CO 2, the welding wire wound in the form of a coil is inserted into the torch by the feed motor automatically. The welding wire that is electrified through the contact tip becomes the electrode that creates an arc between it and the base metal. Arc heat melts the fence and base metal to join two pieces of the base metal. In this case, so that the weld metal is not affected by oxygen and nitrogen present in the atmosphere, CO 2 is supplied from the torch nozzle to protect the weld pool.
Compared with protected metal arc welding, arc welding with CO 2 has the following advantages and disadvantages.
- The diameter of the wire is meagre, the density of the welding current is high, and therefore, the deposition rate is tremendous.
- A suitable concentration of the arch makes a deep penetration effective.
- The deposition rate is high, and slag formation is low, which makes it unnecessary to remove the slag after each pass.
- The arc generation rate is high, which reduces the cost of welding and makes the process more economical.
- The hydrogen in the weld metal is low, which contributes excellent mechanical properties and cracking resistance.
- You need a windscreen against winds at a speed of 2m/sec. Or higher.
- Even if a long conduit cable is used, the moving area of the welder is limited.
- The price of the power source is high.
If these advantages and disadvantages are compared with those of the protected metal arc welding process, it is evident that arc welding with CO 2 offers greater efficiency, lower welding costs, and a better economy. Such advantageous effects can be maximized in automatic welding, in particular in robotic welding. This means that you need Co2 welding machine (ตู้ เชื่อม co2 which is the term in thai) for greater reliability and efficiency.