Welding with CO2 gas protection: optimal current and voltage control

CO2 gas protected welding involves melting the welding wire using welding voltage as the energy source.

The welding wire melts more quickly as the voltage increases.

The welding current is determined by balancing the wire feed speed with the melting speed.

1. Welding current

The selection of welding current should be based on various welding conditions such as plate thickness, welding position, welding speed, material and other relevant parameters.

For protected welding with carbon dioxide gas, it is crucial to ensure that the welding current matches the welding voltage and that the wire feed speed and welding voltage are consistent with the meltability of the welding wire. This is necessary to maintain arc length stability during the welding process.

Relationship between welding current and wire feed speed

For a given welding wire, increasing the cable size results in a higher wire feed speed.

Likewise, when the current remains constant, using a thinner welding wire will result in a faster wire feed speed.

2. Welding voltage

Welding voltage, also known as arc voltage, is responsible for providing the required welding energy.

Higher arc voltage translates into greater welding energy, faster welding wire melting, and increased welding current.

Arc voltage can be calculated by subtracting the welding circuit loss voltage from the welder output voltage. This can be expressed using the following formula:

you bow = you exit – YOU loss

Assuming the welding machine has been installed in accordance with installation requirements, any loss of voltage is primarily due to cable length.

In situations where welding cables need to be extended, the output voltage of the welding machine can be adjusted according to the table below:

Welding current Cable length 100A 200A 300A 400A 500A
10m About 1V About 1.5V About 1V About 1.5V About 2V
15m About 1V About 2.5V About 2V About 2.5V About 3V
20m About 1.5V About 3V About 2.5V About 3V About 4V
25m About 2V About 4V About 3V About 4V About 5V

3. Welding Voltage Setting

Choose the appropriate welding current based on the plate thickness and welding conditions, and then calculate the welding voltage using 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 400A welding current is selected, the welding voltage is calculated as follows:

Welding voltage=(0.05 × 400+14 ± 3）

=(20+14±3)V

=(34±3)V

4. Influence of welding voltage on welding effect

When the voltage is too high, the arc length increases, leading to larger spatter particles that can easily produce pores. Furthermore, the weld bead becomes wider, while the solution depth and excess height become smaller. This can also result in a “pattern! drum!” sound.

Conversely, when the voltage is too low, spatter increases as the welding wire is inserted into the base metal. Furthermore, the weld bead narrows and both the solution depth and excess height increase. This can lead to a “bang! boom! boom!” sound.

Recommended for you:

  • Welding Training 101: Everything You Need to Know
  • Welding Glossary: ​​292 Crucial Welding Terms
  • Common Welding Processes for Thin Plates: Expert Guide
  • Welding gas: everything you need to know
  • Special Foundry: Everything you need to know
  • The Ultimate Guide to Welding: Everything You Need to Know

Conteúdo relacionado

Back to blog

Leave a comment

Please note, comments need to be approved before they are published.