Class 12 Copper Tungsten
Class 12 Copper Tungsten contains 20% copper and 80% tungsten. Stronger than Class 10 and 11 Copper Tungsten, it is commonly used in heavy-duty projection welding electrodes, electro-forming and -forging electrode facings for upsetting studs and rivets, and cross wire welding. It is also used in the liners of some specialty-shaped explosive charges for the defense and oil and gas industries.
RWMA Class 12 · Trade designation 30W3
| Composition | Density | Hardness (min) | Electrical Conductivity | Thermal Conductivity |
| 20% Cu / 80% W | 0.580 lb/in³ (15.7 g/cm³) | Rockwell B 103 | 41% IACS | 104 BTU/ft·h·°F (180 W/m·K) |
Copper Tungsten Class 12 (30W3)
Class 12 material is specifically recommended for heavy-duty projection welding electrodes and for die facings in electro-forming and electro-forging applications. It is suitable as die material for electrical upsetting of rivets and studs.
Material Properties (Class 12 — 30W3)
• Composition: 20% copper / 80% tungsten
• RWMA Class: 12
• Trade designation: 30W3
• Hardness: Rockwell B 103 (minimum)
• Electrical conductivity: 41% IACS
• Thermal conductivity: 104 BTU/ft·h·°F (180 W/m·K)
• Tensile strength: 170 ksi (1,172 MPa)
• Density: 0.580 lb/in³ (15.7 g/cm³)
How Class 12 Compares to Other Copper Tungsten Classes
Class 12 sits near the high-tungsten end of the copper-tungsten family. Compared to Class 10 and Class 11, it trades electrical conductivity and machinability for greater hardness, strength, and wear resistance — making it the choice for heavy-duty work where electrode deformation, not current capacity, limits tool life.
| Property | Class 10 | Class 11 | Class 12 |
| Composition | 45% Cu / 55% W | 25% Cu / 75% W | 20% Cu / 80% W |
| Hardness (min) | Rockwell B 90 | Rockwell B 98 | Rockwell B 103 |
| Electrical conductivity | 47% IACS | 44% IACS | 41% IACS |
| Best suited for | Flash & butt welding | Projection welding, dies | Heavy-duty projection welding, upsetting dies |
Specify Class 12 over Class 11 when the application involves heavy-duty projection welding, electrical upsetting of studs and rivets, cross wire welding, or electro-forging die facings — anywhere the electrode must resist deformation under high mechanical load. Where conductivity matters more than hardness, Class 11 or Class 10 is the better fit.
Machinability
With 80% tungsten, Class 12 is the hardest of the common copper-tungsten grades and is more demanding to machine than Class 10 or Class 11. Turning, milling, and drilling are possible with carbide tooling, but EDM and grinding are often preferred for finished geometries and tight tolerances. NSRW produces custom-machined Class 12 electrodes, die facings, and inserts to print.
Frequently Asked Questions
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What is Class 12 copper tungsten?
Class 12 copper tungsten is an RWMA-classified resistance welding electrode material composed of 20% copper and 80% tungsten, also known by the trade designation 30W3. It is used for heavy-duty projection welding electrodes and electro-forging die facings.
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What is the composition of Class 12 copper tungsten?
Class 12 has a nominal composition of 20% copper and 80% tungsten by weight. It is produced by infiltrating a sintered tungsten skeleton with molten copper, forming a two-phase composite rather than a true alloy.
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What is the difference between Class 11 and Class 12 copper tungsten?
Class 11 contains 25% copper and 75% tungsten; Class 12 contains 20% copper and 80% tungsten. Class 12 is harder, stronger, and more wear-resistant, while Class 11 has higher conductivity and is easier to machine.
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What is Class 12 copper tungsten used for?
Class 12 is used for heavy-duty projection welding electrodes, electro-forming and electro-forging die facings, electrical upsetting of studs and rivets, cross wire welding, and shaped charge liners in defense and oil and gas applications.
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Is Class 12 copper tungsten the same as 30W3?
Yes. 30W3 is the industry trade designation for RWMA Class 12 copper tungsten with a nominal 20% Cu / 80% W composition.