In TIG welding (tungsten argon arc welding), the polarity of the tungsten electrode directly affects the arc characteristics, heat distribution, electrode life, and weld quality. The electrode polarity required for different materials and welding methods also varies, and the following is a detailed explanation of three common connection methods.
1.DC positive connection (Dcen: Direct Current Electrode Negative) – tungsten electrode connected to the negative electrode
This is the most common and commonly used polar connection method in TIG welding.
Connection method: the negative electrode of the welding machine is connected to the tungsten electrode, and the positive electrode is connected to the workpiece;
Heat distribution: About 70% of the arc heat is concentrated on the workpiece, which is conducive to the formation of penetration depth;
Applicable materials: stainless steel, carbon steel, copper, titanium and most other metal materials;
Merit:
The arc is concentrated and the welding penetration depth is large;
The electrode is not easy to burn out and has a long life;
The arc is stable and the weld is well formed.
Conclusion: When welding most metals, the tungsten electrode should be connected to the negative electrode (DCEN).
2.DC reverse connection (DCEP: Direct Current Electrode Positive) – tungsten electrode connected to the positive electrode
Connection method: the positive electrode of the welding machine is connected to the tungsten electrode, and the negative electrode is connected to the workpiece;
Heat distribution: about 70% of the heat is concentrated in the tungsten electrode, and the electrode is seriously ablated;
Merit:
It can be used to remove oxide film on the surface of aluminum, magnesium and other metals;
Shortcoming:
The electrode is easy to burn and the arc is unstable;
shallow melt depth and low efficiency;
Practical application: It is rarely used in TIG welding and is only used for special occasions or surface cleaning.
Conclusion: DCEP is not suitable for conventional TIG welding, because the electrode burns out quickly and the welding quality is difficult to control.
3.Alternating Current (ac) – Alternating Positive And Negative Electrodes Of Tungsten Electrodes
Applicable occasions: mainly used for welding aluminum and aluminum alloys, magnesium and other metals with oxide film;
Peculiarity:
AC current switches polarity multiple times per second;
In the positive half wave, the electrode is the positive electrode, which can achieve “cathodic cleaning”;
In negative halfwaves, the electrode is negative and helps the metal melt;
Recommended electrodes: Use zirconium tungsten or lanthanum tungsten electrodes to withstand the spherical effects of AC waveforms.
Conclusion: When welding light metals such as aluminum and magnesium, AC power should be used, and the polarity of the electrodes changes alternately.
More details of tungsten electrodes, please visit website: http://tungsten.com.cn/tungsten-electrodes.html
Please contact CHINATUNGSTEN for inquiry and order of tungsten needles:
Email: sales@chinatungsten.com
Tel.: +86 592 5129595
