Adjustment of Welding Machine Current and Voltage (CO2 Gas Shielded Welding)

CO2 gas shielded welding is the melting energy of welding wire provided by welding voltage.

The higher the voltage is, the faster the welding wire melts;

The welding current is actually the result of the balance between wire feeding speed and melting speed.

1. Welding current

The welding current shall be selected according to the welding conditions (plate thickness, welding position, welding speed, material and other parameters).

Therefore, the carbon dioxide gas shielded welding current must match the welding voltage, and the wire feeding speed and welding voltage must be consistent with the melting capacity of the welding wire to ensure the stability of the arc length.

Adjustment of Welding Machine Current and Voltage (CO2 Gas Shielded Welding) 1
Relationship between welding current and wire feeding speed

For the same welding wire, the larger the cable is, the faster the wire feeding speed is.

With the same current, the thinner the welding wire, the faster the wire feeding speed.

2. Welding voltage

Welding voltage, namely arc voltage, provides welding energy.

The higher the arc voltage, the greater the welding energy, the faster the welding wire melts, and the greater the welding current.

The arc voltage is equal to the output voltage of the welder minus the loss voltage of the welding circuit, which can be expressed by the following formula:

Uarc = Uoutput – Uloss

If the installation of the welding machine meets the installation requirements, the voltage loss mainly refers to the voltage loss caused by the extension of the cable.

If the welding cable needs to be extended, the output voltage of the welding machine can be adjusted according to the following table:

Welding current  Cable length100A200A300A400A500A
10mAbout 1VAbout 1.5VAbout 1VAbout 1.5VAbout 2V
15mAbout 1VAbout 2.5VAbout 2VAbout 2.5VAbout 3V
20mAbout 1.5VAbout 3VAbout 2.5VAbout 3VAbout 4V
25mAbout 2VAbout 4VAbout 3VAbout 4VAbout 5V

3. Setting of welding voltage

Adjustment of Welding Machine Current and Voltage (CO2 Gas Shielded Welding) 2

Select the welding current of the corresponding plate thickness according to the welding conditions, and then calculate the welding voltage according to the following formula:

< 300A: welding voltage=(0.05 × Welding current+14 ± 2) V

> 300A: welding voltage=(0.05 × Welding current+14 ± 3) V

Example 1: If the welding current is 200A, the welding voltage is calculated as follows:

Welding voltage=(0.05 × 200+14 ± 2)

=(10+14 ± 2) V

=(24 ± 2) V

Example 2: If the welding current 400A is selected, the welding voltage is calculated as follows:

Welding voltage=(0.05 × 400+14 ± 3)

=(20+14 ± 3) V

=(34 ± 3) V

Adjustment of Welding Machine Current and Voltage (CO2 Gas Shielded Welding) 3

4. Influence of welding voltage on welding effect

When the voltage is too high: the arc length becomes longer, the spatter particles become larger, which is easy to produce pores, the weld bead becomes wider, the solution depth and surplus height become smaller, and there is a “patter! Patter!” Sound.

When the voltage is low: when the welding wire is inserted into the base metal, the spatter increases, the weld bead narrows, the solution depth and surplus height increase, and there is a “Bang! Bang! Bang!” Sound.

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