Cupal® | Dispersion Strengthened Copper - C15725, RWMA Class 20
upal® delivers cost-effective performance for resistance welding applications. This dispersion strengthened copper electrode contains 0.25% aluminum oxide. It outperforms traditional copper chrome and copper chrome zirconium electrodes.
What Makes Cupal Different
Luvata manufactures Cupal through a cold-forming process. This process disperses aluminum oxide particles throughout the copper matrix. The result is an electrode that resists thermal degradation better than conventional alloys.
The aluminum oxide strengthening remains stable at high temperatures. Standard copper alloys soften when exposed to welding heat. Cupal maintains its hardness and conductivity throughout extended welding cycles.
Performance Advantages
Extended Electrode Life
Cupal electrodes last significantly longer than conventional alternatives. The dispersion strengthened structure resists mushrooming at the contact surface. You’ll dress tips less frequently and replace electrodes less often.
Anti-Stick Properties
The aluminum oxide dispersion prevents material buildup on electrode faces. Coated steels and galvanized materials release cleanly from Cupal electrodes. This reduces downtime for tip cleaning and maintenance.
Reduced Energy Requirements
Cupal’s high electrical conductivity (87% IACS) delivers current efficiently. You can often reduce welding parameters compared to other RWMA Class 20 materials. Lower energy input reduces operating costs.
Works on All Steel Types
Engineers use Cupal successfully on coated and uncoated steels. It performs well on galvanized, zinc-coated, and bare steel substrates. The same electrode handles multiple material types without frequent changes.
Improved Production Uptime
Mushrooming resistance keeps electrode faces flat longer. Consistent face geometry maintains weld quality throughout the electrode’s life. Production runs continue without interruption for tip maintenance.
Technical Specifications
Alloy Classification: C15725 CuAl₂O₃, EN ISO 5182 C20/1, RWMA Class 20
Chemical Composition:
- Aluminum: 0.25% by weight as Al₂O₃
- Copper: Balance
Physical Properties at 20°C:
- Density: 8.86 g/cm³
- Thermal Conductivity: 344 W/m·K
- Electrical Conductivity: 87% IACS
- Thermal Expansion (20-150°C): 16.6 x 10⁻⁶ m/mK
- Softening Temperature: 1083°C
Mechanical Properties:
- Tensile Strength: 441-489 MPa
- Yield Strength: 365-413 MPa
- Elongation: 18-23%
- Hardness: 140 HV (76 HRB)
Applications
Male and Female Electrodes
Cupal works in both upper and lower electrode positions. Use it for spot welding applications across automotive and manufacturing industries.
Backing Dies
The material’s thermal stability makes it ideal for backing electrodes. It performs well in series welding and indirect welding configurations.
Projection Welding
Cupal electrodes handle projection welding applications effectively. The anti-stick properties work particularly well with embossed or projected nuts and fasteners.
Manufacturing and Quality
Luvata produces Cupal through precision cold-forming technology. This process ensures consistent grain structure throughout each electrode. Every electrode in a production lot maintains identical properties.
The manufacturing process uses extremely pure, oxygen-free copper. No phosphorus enters the alloy composition. This purity contributes to Cupal’s superior electrical properties.
Identifying Cupal Electrodes
You can easily identify Cupal electrodes by their distinctive knurl pattern. Each electrode has four pairs of knurls spaced evenly around the periphery. This marking system ensures traceability throughout your production process.
Available Sizes and Custom Options
We stock Cupal in most industry-standard sizes and geometries. Common sizes include 13mm, 16mm, and 20mm diameters. We can also cold-head custom shapes to your exact specifications.
Standard tapers include 4RW and 5RW configurations. Special tapers and face geometries are available upon request.
Quality Documentation
All Cupal material is fully traceable. Acceptance test certificates (EN 10204 3.1 B) are available upon request. These certificates verify alloy composition and mechanical properties.
Packaging
Most Cupal electrodes ship in cartons of 500 pieces. This packaging protects electrodes during shipping and simplifies inventory management.
Why Choose Cupal
Cupal offers an excellent balance of performance and value. It costs less than Nitrode while delivering superior performance to conventional alloys. For operations running coated steels or seeking longer electrode life, Cupal provides a cost-effective solution.
The material’s consistent properties reduce process variation. Your welding parameters remain stable across multiple electrodes and production runs. This consistency improves weld quality and reduces scrap.