Seamlessly joined? Comparing cast and soldered electrodes for spot welding.

Electrodes made from tungsten-lanthanum or TZM with a copper shaft are suitable for the high stresses involved in resistance spot welding. But cavities in the solder between the electrode and the shaft have a negative impact on the quality of the weld.

Bye, bye cavities Tungsten-lanthanum and the molybdenum alloy TZM have a high melting point and are stable at high temperatures. Copper electrode holders dissipate heat quickly. But with resistance welding, it is not only the material that matters; the manufacturing processes are also important.

Many manufacturers join tungsten-lanthanum or TZM and copper using a soldering process. The solder is not distributed evenly at the join between the electrode material and the electrode holder. This results in cavities that have an impact on the electrical resistance and thermal conductivity during welding. The problem is that the quality of the weld can fluctuate when electrodes are replaced.

Plansee does not employ any soldering processes when manufacturing its resistance welding electrodes, and instead casts its tungsten-lanthanum and TZM electrodes with copper in a vacuum. Molten copper completely encloses the electrode, creating a seamless join between the two materials. The welding parameters remain constant whenever an electrode is replaced. And the service life of the electrodes is also longer.

The figures show micro sections of a soldered electrode insert (left) and of a cast WL20 electrode from Plansee (right).


The figure on the left clearly shows the cavities at the join between the base of the WL20 electrode and the copper shaft.

Meet us at the "Welding and Cutting" show


Our team is happy to tell you more about the properites of our back-casted electrodes for resistance welding at the "Welding and Cutting" show in Essen from 16 - 21 September.

Read more about ourelectrodes for resistance welding.