1. What Are Bimetallic Lugs
Bimetallic lugs are specialized connectors used to join aluminum cables to copper bus bars or terminals. They address a critical issue in electrical installations: connecting two dissimilar metals without causing corrosion. Each lug consists of two main components—an aluminum barrel and a copper palm (or pad)—fused together through a process known as friction welding.
Why does this matter? Aluminum and copper have different electrical and mechanical properties. When joined directly, they can trigger galvanic corrosion, leading to overheating, connection failure, and system downtime. Bimetallic lugs eliminate this risk by creating a stable and long-lasting interface.
You’ll commonly find these connectors in control panels, switchgear systems, solar plants, and other power distribution setups. Regardless of the name—whether referred to as bimetallic lugs or bi-metal cable connectors—they serve one essential purpose: enabling safe, reliable aluminum-to-copper connections.
DTL 2 Bimetallic Cable Lug 2 1
2. Why Bimetallic Lugs Are Important & Benefits
2.1 Prevention of Galvanic Corrosion
This is the number one reason to use bimetallic lugs. When aluminum and copper touch directly, a chemical reaction begins. This is known as galvanic action. It leads to oxidation, heat build-up, and breakdown of the joint.
By using Al-Cu lugs, the aluminum barrel connects to the aluminum conductor, and the copper palm connects to the copper busbar. Friction welded at the joint, these lugs block the chemical reaction from ever starting.
2.2 Improved Conductivity
Friction welding ensures a strong molecular bond. There’s almost no added resistance at the junction. The electrical conductivity across the joint is nearly as good as a solid copper lug. SUNJ’s tests show contact resistance under 10 µΩ, well within IEC 61238-1 and UL 486A-486B limits. That means less energy loss and less heat.
2.3 Cost-Effectiveness
Copper is expensive. Aluminum is lighter and cheaper. A bimetallic connector lets you take advantage of both. You get the conductivity of copper and the cost benefit of aluminum. In large-scale power distribution systems, this can reduce project cost significantly.
Also, tools and installation labor for bi metal lugs connectors are the same as for single-metal lugs, so you save without sacrificing performance.
2.4 Thermal Stability and Mechanical Strength
Bimetallic lugs can handle heat and stress well. In SUNJ’s thermal rise test, the lug showed less than 30°C rise under full load, below the industry standard of 50K.
They are also strong. The friction-welded joint holds under tension. In tensile tests, the joint holds even when the cable breaks first. That proves the bimetal cable lug isn’t the weak point in the system.
2.5 Corrosion Resistance and Longevity
These lugs are built to last. The aluminum barrel is filled with anti-oxidation grease. The copper palm is tin-plated. These layers protect against moisture, air, and chemical exposure. Many are RoHS Compliant, ensuring safe materials and longer service life.
The alumiconn aluminum to copper lug style is often preferred in residential and industrial setups for this very reason.
3. Types of Bi-metallic Lugs & Connectors
3.1 Standard Bimetallic Lugs
This is the most common type. It features a single aluminum barrel friction-welded to a copper palm with a mounting hole. Used in LV connections, it’s ideal for panel boards, junction boxes, and small-scale switchgear applications.
3.2 Bolted Bimetallic Lugs
Instead of crimping, these use mechanical bolts. They are perfect for field installations where crimp tools are not practical. These bi metal lugs connectors allow controlled torque tightening and are suitable for maintenance-heavy environments.
3.3 Compression Bimetallic Lugs
These are crimped using compression tools. They provide a permanent, vibration-resistant joint. Compression types are often used in MV terminations, substations, and renewable energy applications where reliability is critical.
3.4 Long Barrel Bimetallic Lugs
The longer aluminum barrel allows better conductor insertion and more crimping area. This increases mechanical strength and lowers electrical resistance. Long barrel versions are widely used in utility and large-scale power distribution systems.
4. Manufacturing Process of Bimetallic Lugs
4.1 Material Selection and Pre-Treatment
High-purity aluminum (99.6%) and copper (99.95%) are selected. The copper part is usually tin-plated to improve corrosion resistance. Aluminum barrels are anodized or chemically treated. Anti-oxidation grease is added to prevent moisture entry.
4.2 Stamping and Forming
The copper palm is punched, drilled, and shaped. The aluminum barrel is formed through cold forging. Each part is precisely machined to ensure a perfect friction weld interface.
4.3 Friction Welding (Solid-State Bonding)
This is the heart of the process. The aluminum barrel and copper palm are pressed together and rotated at high speed. Friction generates heat, and the metals bond at the molecular level without melting. The result is a strong, seamless joint that’s highly conductive.
This process distinguishes friction welded lugs from traditional connectors.
4.4 Heat Treatment
The lugs are annealed to relieve internal stress. This improves mechanical performance and ensures consistent crimping results.
4.5 Surface Treatment
The copper palm is plated with tin or silver. The aluminum may be polished or coated. The inner barrel is pre-filled with contact grease. Barrel ends are sometimes sealed with caps to block dust and moisture.
4.6 Assembly and Inspection
Each lug is visually inspected and tested for weld strength, dimensions, and contact resistance. Some are checked by X-ray to ensure no voids exist in the weld. All SUNJ lugs follow IEC 61238-1 and UL 486A-486B compliance standards.
5. Conclusion
China Bimetallic Lugs and Connectors
Bimetallic lugs and connectors are essential for safe and efficient connections between aluminum conductors and copper busbars. They prevent galvanic corrosion, improve conductivity, and provide thermal and mechanical stability.
With types ranging from standard crimp lugs to long barrel and bolted versions, they’re used in LV connections, MV terminations, and across all types of switchgear applications.
Thanks to advanced manufacturing, such as friction welding and corrosion protection, today’s bimetallic cable lugs offer better durability and performance than ever before. Whether you’re sourcing Al-Cu lugs for solar, industrial, or utility projects, they’re a cost-effective and dependable solution.
Ready to upgrade your connection reliability? Choose the right bimetallic connector for your system today.