The five main effects of the electrode cap on welding: material conductivity, end-face shape fitment, wear state management, cooling system performance and mounting accuracy control, and resolves the root causes of problems such as false welding, spattering and weld core deviation.
I. Key impact of the material on the Electrode Caps analysis
Electrical conductivity and thermal conductivity
Highly conductive materials (such as chrome zirconium copper): uniform current density, reducing welding spatter, but easy to soften at high temperatures (softening temperature of about 550 ℃).
Aluminium oxide dispersible copper (Al₂O₃-Cu): high temperature resistance (softening temperature up to 900°C), suitable for welding galvanised sheets, aluminium alloys and other materials prone to adhesion, extending service life by 3-5 times.
Hardness and wear resistance
Electrode caps with insufficient hardness are prone to deformation under high pressure, resulting in increased contact area, reduced current density and triggering false welding.
Poor abrasion resistance material (such as pure copper) in the welding of plated materials, the end face is easy to be contaminated by zinc, aluminium and other metals, need to be frequently repaired and ground.
II, the influence of shape design
End face shape
Flat electrode cap (F-type): large contact area, suitable for thin plate welding (0.5-3mm), reduce the welding core offset.
Spherical electrode cap (R type): concentrated current density, suitable for thick plate or high strength steel welding, but easy to stick on the plating material.
Tapered Electrode Cap (P type): Unique tapered end design, showing significant advantages in thick plate welding and high strength material processing.
Electrode cap diameter
Diameter too small (such as Φ8mm): current density is too high, easy to burn through the thin plate or produce spatter.
Too large diameter (e.g. Φ16mm): too slow heat dissipation, resulting in overheating and deformation of the electrode, shortening the service life.
Suggested matching: choose Φ10mm for plate thickness ≤1mm, Φ13mm for 1-3mm, and Φ16mm for >3mm.
III. Influence of wear state
Oxidation and deformation of end face
Thickening of oxidised layer (＞0.2mm) will increase the contact resistance, reduce the effective current, and lead to insufficient strength of welded joints.
End face depression or eccentric wear (common in continuous robot welding) will lead to uneven pressure distribution and welding core shift.
Lifecycle management
Galvanised steel welding: electrode cap life of approx. 3000-5000 points, regular endface resharpening is required (every 1000 points).
Aluminium alloy welding: life shortened to 800-1500 points, need to use alumina copper electrode and strengthen the cooling.
IV. Impact of cooling effect
Internal cooling waterway design
When cooling is insufficient, the temperature of the electrode cap exceeds the softening point of the material (e.g., chromium-zirconium copper > 550°C), accelerating the deformation of the end face.
Optimisation: adopt double-circulation cooling system (e.g. robotic welding clamp), and the water temperature is controlled at 20-30℃.
Insufficient cooling water flow
flow <4L/min, the electrode cap cooling efficiency decreased by 40%, resulting in an increase in welding spatter rate of 15-20%.
V. Influence of Installation and Maintenance
Installation Accuracy
Poor matching of the threads of the electrode cap and the electrode rod (such as untightened or tilted installation) will lead to an increase in the contact resistance and localised overheating melting damage.
Cleaning and Maintenance
Oxidation or oil contamination on the contact surface of the electrode rod will reduce the conductivity, which needs to be sanded regularly with sandpaper (≥400 mesh) and coated with conductive grease.