Cu-Al Composite Metal Stamping

Cu-Al Composite Stamping Manufacturing Capability

Material Selection & Preparation

Raw Material: Select a Cu-Al composite sheet (explosion-welded, roll-bonded, or friction-welded) with the required copper-to-aluminum thickness ratio. Common ratios are 1:1, 1:2, or 1:5 depending on conductivity and cost requirements.

Material Inspection: Verify bond strength (peel test or ultrasonic test) and thickness uniformity before stamping.

Cutting: The composite sheet is cut into blanks of the required size for single-station stamping.

The Stamping Process (Single-Station Die)

Unlike progressive dies, a single-station die performs all operations in one press stroke, or in a sequence of manually fed operations.

Step 1 – Blanking & Piercing: The outer profile of the connector is cut, and mounting holes are punched in a single stroke. The die must be designed to handle the different shear strengths of copper and aluminum.

Step 2 – Forming / Bending: The blank is placed into a forming die. A punch and die create the arch or bend with the proper radius to avoid cracking at the interface.

Step 3 – Coining / Flattening (Optional): The contact areas may be coined to improve flatness and surface finish for better electrical contact.

Step 4 – Cut-off / Separation: If multiple parts are stamped from one blank, they are separated.

Post-Stamping Operations

Deburring: Remove burrs from punched holes and edges, especially on the copper side, to ensure safe handling and optimal electrical contact.

Surface Treatment: Selective plating (tin, nickel, or silver) may be applied to the copper side to prevent oxidation and improve solderability.

Cleaning: Remove stamping oil and debris.

Inspection: Verify dimensions, bond integrity, and surface quality.

Quality Control (In-Process)

Visual Inspection: Check for cracks, delamination, or separation at the Cu-Al interface.

Dimensional Check: Micrometers and optical comparators verify length, width, hole diameter, and bend angle.

Bond Strength Test: Peel test or ultrasonic inspection to ensure the Cu-Al bond is intact after stamping.

Plating Thickness Test: XRF verifies plating thickness on the copper side.

Delamination at the Cu-Al Interface

Challenge: The copper and aluminum layers may separate or delaminate during stamping, especially during shearing, bending, or coining.

Root Cause: Poor bond strength; excessive shear stress; improper die clearance; sharp corners; insufficient material ductility.

Countermeasure: Use high-quality Cu-Al composite material with verified bond strength; optimize die clearance for bimetal shearing; increase bend radii; avoid sharp corners; preheat material if necessary; use a slower stamping speed to reduce impact stress.

Cracking at the Bend / Arch

Challenge: The arch or bend area may develop cracks, especially on the aluminum side, which has lower ductility than copper.

Root Cause: Aluminum is softer and more prone to cracking; bend radius too small; insufficient material thickness; excessive strain.

Countermeasure: Design generous bend radii (typically ≥ 1.5x material thickness); use progressive forming (multiple small bends instead of one large bend); anneal the aluminum side if possible; optimize punch and die radius.

Burr Control & Hole Quality

Challenge: Burrs on punched holes and edges can affect electrical contact, cause short circuits, or injure operators.

Root Cause: Dull cutting edges; improper clearance for bi-metal materials; tool wear.

Countermeasure: Maintain sharp cutting edges; use carbide inserts for high-volume production; optimize clearance for copper-aluminum combination; implement in-process burr inspection; add deburring or tumbling as a secondary operation.

Dimensional Accuracy & Flatness

Challenge: The part may warp or lose flatness after stamping due to the different thermal expansion coefficients and elastic moduli of copper and aluminum.

Root Cause: Residual stress from bonding; uneven material flow during stamping; springback differences between the two metals.

Countermeasure: Use stress-relief annealing before stamping; optimize die design with proper clamping and support; use coining to improve flatness; implement in-process flatness inspection.

Die Wear & Maintenance (Single-Station Die)

Challenge: Stamping Cu-Al composite materials causes faster die wear than stamping single metals due to the abrasive nature of aluminum and the hardness difference between layers.

Root Cause: Abrasive aluminum oxide; high shear stress; insufficient lubrication; improper die material.

Countermeasure: Use tungsten carbide (YG20/YC20C) or high-vanadium tool steel (DC53) for high-wear stations; apply proper lubrication; implement a preventive maintenance schedule; monitor die wear with in-process sensors.

Material Springback & Deformation

Challenge: Copper and aluminum have different springback behaviors, causing dimensional deviation after bending.

Root Cause: Different elastic moduli; residual stress; improper bend radius; insufficient over-bending.

Countermeasure: Use springback compensation in die design; increase bend radius; apply stress-relief annealing; use over-bending techniques; optimize punch and die clearance.

Selective Plating & Masking

Challenge: Plating must be applied only to the copper side, while the aluminum side must be protected from plating solution.

Root Cause: Aluminum is reactive and can be attacked by plating chemicals; masking is difficult on complex shapes.

Countermeasure: Use selective plating with masking fixtures; apply a protective coating to the aluminum side before plating; use brush plating or spot plating for critical areas; verify plating adhesion and coverage.

Industries We Serve

Delivering precision Cu-Al composite material stampings and components across diverse sectors.

New Energy Vehicles (EVs) – Battery pack busbars, cell connectors, and high-voltage distribution modules.

Power Distribution & Switchgear – Cu-Al transition joints, electrical busbars, and transformer terminals.

Battery Packs & Energy Storage – Energy storage rack connectors and battery interconnects.

High-Voltage Electrical Connectors – Bi-metal lug terminals and Cu-Al composite connectors.

Renewable Energy Systems – Solar and wind power busbars and conductive connections.

Industrial Busbars & Conductors – Cu-Al composite busbars and high-current conductive parts.

Other Electrical Transition Joints – Custom Cu-Al composite stampings for specialized applications.

Our Process Flow

DFM Design → Die Manufacturing (CNC / Wire EDM / EDM) → Die Assembly → Trial Run (T1) → Small-Batch Validation → Mass Production

DFM – Review drawings, blank layout, stations, clearance, springback, and Cu-Al interface stress analysis.

Die Manufacturing – CNC, wire EDM, sinker EDM, grinding, heat treatment, coating, inspection.

Die Assembly – Assemble plates, punches, pilots, springs; set clearance for bi-metal shearing and feed.

Trial Run (T1) – Mount die, run samples, check dimensions, burr, angle, delamination; adjust.

Small Batch – 500–5,000 pcs; CPK/PPK, tool wear, bond integrity, plating, PPAP approval.

Mass Production – Stable stamping, SPC, maintenance, selective plating, packaging.

Why Choose Yixing Technology?

Our company excels in meeting these requirements through our advanced process capabilities and expertise:

Ultra-Precision – Critical features (hole diameter, hole pitch, bend angle) must be held within tolerances of less than 0.1 mm for reliable electrical connection. Our machining equipment achieves tolerances of ±2 µm, significantly exceeding stamping-die standards.

Delamination-Free Stamping – The Cu-Al interface must remain bonded without delamination during shearing, bending, and coining. Our molds feature optimized clearances and radii specifically designed for bi-metal materials, enabling clean, delamination-free stamping.

Multi-Process Integration – Blanking, piercing, bending, coining, and cut-off integrated into a single die by our specialist mold designers, turning complex operations into one efficient stamping solution.

High-Tonnage Durability – Cu-Al composites are thicker and require higher tonnage than thin terminals. We build molds from high-rigidity, high-toughness materials such as SKD11, DC53, and tungsten carbide alloys, ensuring durability and long service life.

Bi-Metal Expertise – Different shear strengths, springback behavior, and thermal expansion rates make bi-metal stamping uniquely challenging. Our engineers have extensive experience designing dies specifically for bi-metal materials, ensuring consistent quality and minimal waste.