Raytron Technical Review RESEARCH ARTICLE WP-01-06

Clad Welding Process: Core Technology for Bimetallic Bonding

Q: What are the main steps of clad welding process?

Main steps include: 1) Material preparation (cleaning copper strip and core); 2) Copper strip wrapping and forming; 3) Longitudinal seam welding; 4) Multi-pass drawing; 5) Intermediate annealing; 6) Final dimension drawing; 7) Quality inspection. Each step requires precise parameter control.

Q: How to avoid common defects in clad welding?

Delamination: increase welding temperature and pressure; Cracking: add intermediate annealing, control work hardening; Eccentricity: adjust cladding alignment, ensure uniform copper wrapping; Interface defects: control atmosphere, prevent oxidation. Regular equipment maintenance and raw material inspection.

Gao-Lei Xu¹ *

¹RAYTRON Group Technology Research Center, China

^*Corresponding author

Received: 2025-12 Accepted: 2026-02 Published: 03/2026

DOI: 10.1234/raytron.2026.WP-01-06

Abstract

Clad welding is the primary manufacturing process for bimetallic conductors, creating metallurgical bonds between dissimilar metals. This technical review examines roll bonding, extrusion, and diffusion bonding processes, with focus on interface quality, process parameters, and defect prevention.

Key Findings

Clad Welding is Core Technology Clad welding produces high-quality bimetallic conductors by wrapping copper strip around the core material and creating metallurgical bonding. Unlike electroplating, clad welding produces permanent metallurgical bonding.
Process Parameters Determine Bond Quality Welding temperature, pressure, and speed are key parameters affecting bond quality. Optimal welding temperature for CCA is 300-400°C, welding speed 5-20m/min, and pressure must ensure tight contact between copper strip and core.
Drawing Process Achieves Precision Forming Multi-pass drawing process forms the clad-welded composite rod into final dimensions, with single-pass reduction rate of 15-25% and total reduction rate up to 85-95%. Intermediate annealing controls work hardening.
Quality Control Throughout Process From raw material inspection to finished product testing, quality control spans the entire production process. Key indicators include interface bond strength, conductivity, dimensional tolerance, and surface quality.

Keywords

clad welding;roll bonding;bimetallic bonding;interface quality;manufacturing process

1. Introduction

Clad WeldingProductionConductor technology ，through Claddingin Core，achieves two 。

**Fig. 1** Clad Welding Process Flow Diagram

animation

1:00

VIDEO TODO

Video 1 Clad Welding Process Animation

2.

2.1 Core

CoreSurface、，ensures 。

2.2 Claddingmaterial

requires 、 and Surface。

Copper Strip Cladding Aluminum Rod Cross-SectionSchematic Diagram — **Fig. 2** Copper Strip Cladding Aluminum Rod Cross-Section Diagram

3. WeldingProcess

3.1 WeldingParameter

Weldingtemperature 、pressure and speed Impactquality KeyParameter。

WeldingStrengthImpact Curve — **Fig. 3** Effect of Welding Temperature on Bond Strength Curve

3.2 Welding

Main or Welding。

4. DrawingProcess

4.1 DrawingPass Design

**Fig. 4** DrawingPass DesignSchematic Diagram

4.2 Work HardeningControl

requires through AnnealingControlWork Hardening。

5. Interface

InterfaceSchematic Diagram — **Fig. 5** InterfaceformationprocessSchematic Diagram

Interfaceincluding ：、Diffusion、、stable。

6. ProcessOptimization

through ExperimentDesign（DOE）methodsOptimizationProcessParameter。

7.

8. Conclusion

CladdingSoldering ProcessConductorProduction technology ，through OptimizationProcessParametercan quality 。

Frequently Asked Questions

What is the fundamental difference between clad welding and electroplating?

Clad welding produces metallurgical bonding with bond strength >150MPa, layer thickness 20-200μm, and excellent high-temperature performance. Electroplating is mechanical adhesion with bond strength <50MPa, layer thickness typically <10μm, and easy delamination under thermal cycling. Clad welding products have permanent bonding.

What are the main steps of clad welding process?

Main steps include: 1) Material preparation (cleaning copper strip and core); 2) Copper strip wrapping and forming; 3) Longitudinal seam welding; 4) Multi-pass drawing; 5) Intermediate annealing; 6) Final dimension drawing; 7) Quality inspection. Each step requires precise parameter control.

How to avoid common defects in clad welding?

Delamination: increase welding temperature and pressure; Cracking: add intermediate annealing, control work hardening; Eccentricity: adjust cladding alignment, ensure uniform copper wrapping; Interface defects: control atmosphere, prevent oxidation. Regular equipment maintenance and raw material inspection.

Figures

Create clad welding process flow diagram

Fig. 1 Clad Welding Process Flow Diagram

Copper Strip Cladding Aluminum Rod Cross-Section Diagram

Fig. 2 Copper Strip Cladding Aluminum Rod Cross-Section Diagram

Create Welding Temperature on Bonding Strength Impact Curve

Fig. 3 Welding Temperature on Bonding Strength Impact Curve

Drawing Pass Design Diagram

Fig. 4 Drawing Pass Design Diagram

InterfaceFormation ProcessDiagram

Fig. 5 InterfaceFormation ProcessDiagram

Common DefectsSEMPhoto

Fig. 6 Common DefectsSEMPhoto

Tables

Table 1 Process ParametersScope

Parameter	CCA	CCS	NCC
Welding Temperature (°C)	300-400	400-500	350-450
Welding Speed (m/min)	5-20	3-15	5-15
DrawingReducedDiameterRate (%)	15-25	10-20	15-22

Table 2 OriginalMaterial Requirements

Material	Purity	Surface Requirements	Dimensional Tolerance
Copper Strip	≥99.9%	No Oxidation、No	±0.02 mm
Aluminum Rod	≥99.5%	Cleaning、Dry	±0.1 mm
Steel	LowCarbonSteel	Rust Cleaning	±0.1 mm

Table 3 Welding Parameters Optimization

Parameter	LowValue	MostExcellent	HighValue
Temperature (°C)	280	350	420
Compressive Force (MPa)	150	250	350
Speed (m/min)	5	12	20

Table 4 Drawing PassDesign

Pass	Inlet Diameter (mm)	Outlet Diameter (mm)	ReducedDiameterRate (%)
1	10.0	8.5	28
2	8.5	7.2	28
3	7.2	6.1	28
4	6.1	5.2	27

Table 5 Common Defects and Solution

Defects	Reason	Solution
Delamination	BondingNon-Good	ImproveHigh Welding Temperature
Crack	ExcessDegree Processing Hardening	Increase Annealing
CladdingNon-uniform	on in

References

ASTM International ASTM B566-04: Standard Specification for Copper-Clad Aluminum Wire ASTM (2020)
ASM International Welding Handbook ASM International (2021)
Raytron Technical Report Clad Welding Process Optimization Internal Report TR-2025-032 (2025)

Authoritative References

ASTM International IEC (International Electrotechnical Commission) ISO (International Organization for Standardization) SAE International IEEE

Gaolei Xu

Senior Materials Scientist

Credentials & Honors

• CTO, Raytron Group
• Zhejiang Provincial High-level Talent Special Support Program - Young Talent
• Shaoxing "Technology Vice President"
• Shaoxing Science and Technology Commissioner
• Member of National Technical Committee 243 on Heavy Metals (SAC/TC 243/SC2)

National Standards (Lead Author) View Official

GB/T 27671-2011 - Copper Profiles for Electrical Conductors
YS/T 1043-2015 - Silver-bearing Oxygen-free Copper Strip for Motor Commutators
YS/T 974-2014 - Copper and Copper Alloy Strip for Composite Contact Materials
YS/T 1082-2015 - Copper Strip for Lamp Lead Stents

Patents (Inventor) Search Patents

CN104959396A - Production Process of Copper Strip for Composite Contact Materials
CN106077125A - Production Process of Copper Profile for Magnetic Pole Coils
CN201410710206 - Conductive Material for High-speed Railway Traction Motors and Production Method
CN201310719717 - Method for Controlling Strip Shape of Copper Strip Blank by Continuous Extrusion
CN201310720126 - Device for Controlling Strip Shape of Copper Strip Blank by Continuous Extrusion
CN201310376884 - Five-in-one Copper Strip Edge Treatment Equipment for Transformers
CN201420184755 - Continuous Extrusion Die Flow Promotion Device
CN201320761640 - Continuous Extrusion Waste Cleaning Device

Areas of Expertise

Copper-Clad Aluminum (CCA) Technology Copper-Clad Steel (CCS) Manufacturing Bimetallic Composite Materials PV Ribbon for Solar Cells Battery Tab Materials for EV Applications Continuous Extrusion Technology

Selected Publications

• Research and Application of Rolling Method for Manufacturing Metal Laminated Composites, Aluminum Processing Journal, 2008
• Annealing Process Research of Copper-Aluminum Composite Strip
• Research on Preparation Process of Copper/Aluminum Composite Strip for Cables
• Interface Microstructure Evolution of Rolled Copper/Aluminum Composite Strip During Annealing

Mr. Xu Gaolei is a distinguished expert in non-ferrous metal processing with over 15 years of experience. He is recognized as a Young Talent under the Zhejiang Provincial High-level Talent Special Support Program. He leads R&D initiatives in bimetallic composite technologies and has contributed significantly to the standardization of copper and bimetallic materials in China.

Click standard/patent codes to view official documents