Resistance welding welding electrode

spotfor aluminumfor copper

Overview
In the resistance welding process, the parts to be joined are pressed together and heated by an electric current until a molten pool forms at individual points between them. This process requires high currents and high pressing forces. When welding thick sheets, the forces between the electrode and the parts to be joined can reach up to 450 MPa. Our welding electrodes made of tungsten, molybdenum, and their alloys are particularly suitable for welding highly conductive materials such as copper. They are used in the following processes: spot welding, roller seam welding, projection welding, upset welding.

Your advantages at a glance

• Long service life and increased production efficiency
• Reliability due to reproducible quality
• Homogeneity, no chipping
• Constant resistance in the welding process
• High density and hardness – consistent material properties
• Good thermal and electrical conductivity

Product forms and typical applications
Depending on the resistance welding application, Plansee offers solid electrodes and back-cast electrodes (insert electrodes). Solid electrodes are available for direct use; back-cast electrodes combine an electrode insert (W, WL10, Mo, TZM) with a Cu or CuCrZr shaft for improved cooling and electrical contact.

Solid electrodes – typical materials we manufacture from

• W, WL10
• Mo, TZM
• WCu70/30, WCu75/25, WCu80/20, WCu90/10 (infiltrated tungsten-copper composites)
• Tungsten heavy metal alloy (DENSIMET®)

Back-cast (insert) electrodes – typical configurations

• CuCrZr shaft with W, WL10, Mo, or TZM insert
• Cu shaft with W, WL10, Mo, or TZM insert

Why the Plansee back-cast join is superior
Plansee uses a special manufacturing technology that achieves a 100% join between the electrode insert and the electrode shaft. This yields extremely low electrical contact resistance at the insert–shaft interface, producing excellent electrical conductivity and, consequently, high thermal conductivity for highly efficient cooling of the electrode tip. Electrodes produced by soldering processes often contain cavities at the join; such cavities cause variable contact resistance and inconsistent cooling performance, reducing service life.

Observed benefits of back-cast vs. soldered electrodes

• Flawless join → lower and more consistent electrical contact resistance
• Improved thermal conductivity → better cooling of the electrode tip
• Higher bending strength and more stable bending behavior under load
• Lower and more reproducible energy consumption in production (due to optimized contact)
• Process stability and reproducible electrode quality

WCu electrodes for projection welding
Plansee supplies 100% infiltrated tungsten-copper (e.g., W75Cu25, W80Cu20) for projection welding per common standards. These composites combine the strength of tungsten with the thermal/electrical conductivity of copper and offer homogeneous material properties that are easily machined.

Welding processes where these electrodes are used

• Spot welding (sheet thicknesses typically between 0.5 and 3 mm)
• Projection welding (for rivets, nuts, screws and closely spaced welds)
• Roller seam welding
• Upset welding
• Thermode welding (electrode heating with current flowing through the electrode)

Welding recommendation (joining material → recommended electrode material)
JOINING MATERIAL → ELECTRODE MATERIAL
Uncoated steel → CuCrZr / W
Stainless steel → CuCrZr / WCu
Coated steel → CuCrZr / Mo / W / WCu
Pure copper → Mo / W / WCu
Brass (CuZn / tin bronze CuSn) → CuCrZr / Mo / W / WCu
Other Cu alloys → CuCrZr / Mo / W / WCu
Cu + Cu coated alloys → Mo / W / WCu
Other nonferrous metals (e.g., Al, Mg, Ni, Ti) → CuCrZr / Mo / W / WCu
Noble metals (e.g., Ag, Au, Pt) → CuCrZr / Mo / W / WCu
Refractory metals (e.g., Mo, Ta, Cr) → W

Notes on material / microstructure
Plansee material is characterized by an extremely homogeneous structure and a high number of elongated lanthanum oxide particles. The fine, uniform grain structure enables especially high density across the entire cross-section with good hardness. In comparison, coarser or inhomogeneous structures (indicative of less forming) can suggest porosity, which increases the risk of chipping, poorer machining, and compromised welding performance.

Benefits summary

• Short delivery times due to 100% in-house production
• High, reproducible quality standard
• Customer-specific solutions and strict tolerances
• Complete traceability and use of conflict-free materials where applicable
• Possibility of annual contracts with defined inventories / security stock

Characteristics / technical specifications

• Operating capability under high contact pressures (electrode–workpiece forces up to ~450 MPa in thick-sheet welding)
• Materials: W (WL10), Mo (TZM), WCu series (WCu70/30, WCu75/25, WCu80/20, WCu90/10), DENSIMET®
• Back-cast electrode configurations: Cu or CuCrZr shaft with W / WL10 / Mo / TZM insert (100% join)
• Properties: high density, high hardness, homogeneous microstructure, good thermal and electrical conductivity
• Processes supported: spot welding, roller seam welding, projection welding, upset welding, thermode welding
• WCu composite: fully infiltrated tungsten-copper for projection welding; typical grades W75Cu25, W80Cu20