RWMA/Welding Alloys

Aviva Metals has huge inventories of RWMA (Resistance Welding Manufacturing Alliance) alloys available in diameter bars, squares, coil, hex, and plates. We also have abundant inventories of C18200 (Chromium Copper) and C18150 (Chromium Zirconium Copper). Both are available in rounds, hex, and rectangles.

We supply high-performance RWMA (Resistance Welding Manufacturers Association) copper alloys designed for resistance welding, electrical contacts, and other high-conductivity applications. Our selection includes copper-chromium, copper-zirconium, copper-beryllium, and beryllium-free alloys each engineered for excellent thermal and electrical conductivity, as well as superior wear resistance. 

Whether for spot welding electrodes, seam welding wheels, automotive welding arms, or other specialized applications such as machined forgings, Aviva Metals provides precision-crafted RWMA alloys designed to meet your demanding applications. 

• Gun Arms / Holders / Shanks / Dies for all kinds of Robots and Guns
• Caps Manufactured with Cold-Formed Process
• Straight, Single and Double Bend Electrodes for Spot Welding
• Projection (Nut & Stud) Welding Electrodes
• Butt Welding Electrodes
• Seam Welding Wheels
• Refractory Tips/Adapters of Tungsten / Tungsten Copper or Molybdenum Silver Brazed onto Cu.Cr.Zr. / Cr.Cu. Shanks (especially for Non-Ferrous Spot Welding)
• Swivel Head Electrodes
• Threaded / Button Electrodes
• Tip Dresser / Tip Remover / Tip Spanner
• Arms / Horn & Holders for Stationary Welding Machine
• Ceramic Coated Pins for Projection Welding
• Locating Pins in Stainless Steel
• Kickless and Jumper Cables (Water and Air Cooled)
• Flexible Shunts

RWMA defines material classes based on two fundamental properties: electrical conductivity (measured in % IACS — International Annealed Copper Standard) and mechanical hardness (measured on the Rockwell scale). Together, these two properties determine how well an electrode material can transfer electrical current to generate the heat needed for welding, while simultaneously withstanding the mechanical pressure and thermal stress of the welding process.

Applications: Welding Caps, Electrode Adapters, Seam Welding Wheels

Class 1 alloys are chosen when conductivity is the priority over strength. Their high 80% IACS conductivity makes them ideal for welding highly conductive, soft metals such as aluminum, magnesium, brass, and bronze — materials that require efficient current transfer rather than extreme electrode pressure. The lower hardness is acceptable in these applications because the workpieces themselves are soft and don't demand high clamping forces.

Applications: Welding Caps, Electrode Holders, Welding Arms, Nozzles, Butt Welding Dies, Seam Welding Wheels

Class 2 is the most widely used class in the industry, offering the best practical balance between conductivity and hardness. It is the go-to choice for welding mild steel, galvanized steel, tin-plated steel, and most coated steels encountered in automotive, appliance, and general manufacturing. The broader range of applications listed — from caps to holders to welding arms — reflects its versatility. If in doubt, Class 2 is the industry's default starting point.

Applications: Butt Welding Dies, Electrode Holders, Seam Welding Wheels, Electrode Forming Dies, Welding Arms

Class 3 alloys prioritize strength and wear resistance over conductivity, making them suited for applications involving harder materials like stainless steel, high-resistance alloys, and situations where electrodes are subject to severe mechanical stress. The 45% IACS conductivity is still adequate for heat generation, but the 90 HRb minimum hardness is what makes these materials valuable in dies and forming components that must maintain shape under repeated high-pressure cycles. Notably, annealed temper stock is available for Class 3 materials — allowing further machining before hardening.

Applications: Seam Welding Wheels, Butt Welding Dies, Electrode Holders, Welding Arms

Class 4 alloys (primarily Beryllium Copper C17200) are used in the most demanding mechanical environments — where hardness and resistance to deformation under extreme pressure are paramount, and where the lower conductivity (20% IACS) is an acceptable trade-off. These are typically found in flash welding, upset welding, and other high-force applications. The shared applications with Class 3 reflect that Class 4 is essentially an upgrade for the same scenarios when even greater strength is required.

Applications: Specialty and niche applications

Class 5 (Aluminum Bronze, C95400) sits at the extreme end of the hardness spectrum with just 13% IACS conductivity and Rb 92 hardness. This class is rarely used as an electrode in conventional spot welding; instead it appears in structural welding machine components, fixtures, and tooling where electrical conductivity is largely irrelevant but wear resistance and strength are essential.