How does the wire extension length affect the penetration depth?

During CO2 welding, increasing the wire extension length leads to a decrease in the current display value. The main reasons are:

**Resistance heating effect:** The longer the wire extension, the greater the resistance heating, resulting in faster wire melting and a reduction in the actual current used to maintain the arc.

**Current shunting:** Some current is used to heat the wire, causing a decrease in the arc current display value.

**Impact on penetration depth:**

Increasing the extension length enhances resistance heating and accelerates wire melting, but relatively reduces arc energy, leading to a decrease in penetration depth.

For example, when the extension length of a 4mm diameter wire exceeds 50mm, the penetration depth will be significantly reduced.

**Standard recommendation:**

Generally, the extension length should be 10-15 times the wire diameter (e.g., 12-18mm for 1.2mm wire).

For high-current welding, this can be appropriately increased to 20-25mm.