RWMA Materials
Materials meeting RWMA and AWS J1.3 specifications for resistance welding electrode manufacturing. Permanent stock in Monterrey of all 14 RWMA classes. Single piece or volume sales.
RWMA Class Comparison Table
| Class | Conductivity | Hardness | Main Application | Service Life |
|---|---|---|---|---|
| Class 1 | ≥80% IACS | ≥65 HRB | Aluminum, Copper | Medium |
| Class 2 Recommended | ≥75% IACS | ≥75 HRB | Steel, Galvanized | High |
| Class 3 | ≥45% IACS | ≥90 HRB | AHSS, Coated | Very High |
| Class 4 | ≥22% IACS | 36-42 HRC | Molds, Tools | N/A Welding |
RWMA Material Classification
Materials for resistance welding electrodes are classified according to their conductivity and hardness properties. Each class has specific applications.
High Conductivity
Copper Zirconium
UNS C15000 | CuZr
- Conductivity: ≥80% IACS
- Hardness: ≥65 HRB
- Use: Electrodes for aluminum, copper
General Purpose
Copper Chromium Zirconium
UNS C18150 | CuCrZr
- Conductivity: ≥75% IACS
- Hardness: ≥75 HRB
- Use: Carbon, galvanized, stainless steels
- The standard material for 90% of applications
Short electrode life issues?
If your Class 2 electrodes don't last long or deform quickly, consider Class 3 (CuCoBe). Higher hardness = longer life in intensive production.
View Class 3Economical Alternative
Copper Chromium
UNS C18200 | CuCr
- Conductivity: ≥75% IACS
- Hardness: ≥75 HRB
- Use: General applications
High Hardness
Copper Cobalt Beryllium
UNS C17500 | CuCoBe
- Conductivity: ≥45% IACS
- Hardness: ≥90 HRB (AWS J1.3 min)
- Use: High strength steels, coated materials
For injection molds?
If you're looking for beryllium copper for molds or dies (not for welding), you need Class 4. Higher hardness, lower conductivity.
View Class 4High Hardness
Copper Nickel Beryllium
UNS C17510 | CuNiBe
- Conductivity: ≥45% IACS
- Hardness: ≥90 HRB (AWS J1.3 min)
- Use: High production, long-life electrodes
Beryllium-Free
Copper Chromium Nickel Silicon
UNS C18000 | CuCrNiSi
- Conductivity: ≥45% IACS
- Hardness: ≥90 HRB (AWS J1.3 min)
- Use: Beryllium-free alternative (0% Be)
Why choose C18000?
C18000 meets the same AWS J1.3 Class 3 specification (≥45% IACS, ≥90 HRB) but without beryllium. Ideal for companies with zero-beryllium policies or simplified regulatory compliance. Solid bars of C17510/C17500 are safe to handle. View OSHA Safety Guide
Get AdviceMaximum Hardness
Copper Beryllium
UNS C17200 | CuBe
- Conductivity: 22% IACS
- Hardness: 36-42 HRC
- Use: Dies, injection molds, tools
For welding electrodes?
Class 4 has low conductivity (22% IACS). For resistance welding, we recommend Class 3 which balances hardness and conductivity.
View Class 3Refractory Materials
For high temperature applications and maximum durability in insert electrodes.
Tungsten
99.95% W
- Melting point: 3,422C
- Use: Inserts for projection electrodes
Need complex geometries?
Molybdenum (Class 14) offers superior machinability compared to tungsten. It can be drilled and machined to special contours, ideal for custom insert electrodes with mirror finish.
View MolybdenumMolybdenum
Type 360 | 99.95% Mo
- Melting point: 2,623C
- Use: Electrical contacts, cross-wire welding
- Advantage: Machinable (can be drilled)
WLa10 (Tungsten Lanthanum 1%)
1.0% La2O3 | Black #000000
- Composition: 0.8-1.2% Lanthanum Oxide
- Improved thermal balance vs WP
- ISO Band: Black
WLa15 (Tungsten Lanthanum 1.5%)
1.5% La2O3 | Gold #FFD700
- Composition: 1.3-1.7% Lanthanum Oxide
- TIG industry standard
- Longer life, less contamination
- ISO Band: Gold
WLa20 (Tungsten Lanthanum 2%)
2.0% La2O3 | Blue #0000FF
- Composition: 1.8-2.2% Lanthanum Oxide
- Maximum current capacity
- High amperage applications
- ISO Band: Blue
CuW 70/30 / Elkonite 5W3
Copper-Tungsten (CuW)
- Composition: 30% Cu + 70% W
- Conductivity: 48% IACS
- Hardness: 90 HRB
- Density: 14.18 g/cm3
CuW 75/25 / Elkonite 10W3
Copper-Tungsten (CuW)
- Composition: 25% Cu + 75% W
- Conductivity: 46% IACS
- Hardness: 98 HRB
- Density: 14.70 g/cm3
CuW 80/20 / Elkonite 30W3
Copper-Tungsten (CuW)
- Composition: 20% Cu + 80% W
- Conductivity: 42% IACS
- Hardness: 103 HRB
- Density: 15.4 g/cm3
Technical Documentation
Not sure which material you need?
Select your main application and we'll recommend the ideal material:
Frequently Asked Questions - RWMA Materials
What does RWMA mean?
RWMA stands for Resistance Welder Manufacturers Association. It is the organization that establishes standards for resistance welding electrode materials.
What is the difference between C18150 and C18200?
Both are Class 2, but C18150 (CuCrZr) contains additional zirconium that improves sticking resistance on galvanized materials. C18200 (CuCr) is more economical for general applications.
Do you sell bar stock or only electrodes?
We sell both. We have stock of round bars in different diameters for machine shops, and we also manufacture finished electrodes.
What material to use for welding galvanized steel?
We recommend Class 2 CuCrZr (C18150) because the zirconium helps prevent zinc adhesion to the electrode.
Why Class 3 instead of Class 4?
For resistance welding, Class 4 has very low conductivity (22% IACS). Class 3 offers the best balance between hardness and conductivity for welding applications.
Do I need material certificates?
Yes, we provide quality certificates and chemical analysis reports for all our materials upon request.