Raytron Technical Review RESEARCH ARTICLE WP-01-07

Drawing Technology: Precision Forming of Bimetallic Conductors

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-01-07

Abstract

Wire drawing is the critical forming process for bimetallic conductors, determining final dimensions, surface quality, and mechanical properties. This technical analysis examines die design, lubrication, reduction schedules, and defect prevention for CCA, CCS, and NCC drawing.

Key Findings

Bimetallic Deformation Requires Coordination During drawing, core and cladding must deform coordinately. Due to different yield strengths and work hardening behaviors of the two metals, pass design optimization is needed to ensure uniform deformation and avoid interface stress concentration.
Die Design Affects Quality Die angle, bearing length, and surface finish directly affect drawing force and product quality. Optimal die angle is typically 12-18°. Carbide die life is 50-100km, diamond die life can reach 100-200km.
Lubrication is Key Factor Good lubrication reduces drawing force, decreases die wear, and improves surface quality. Oil-based lubricants are suitable for CCA, water-based for CCS (good cooling), and dry lubricants for NCC.
Work Hardening Needs Control Work hardening occurs during drawing, increasing strength but decreasing ductility. Intermediate annealing is needed to restore ductility, with temperature and time determined by material type and degree of work hardening.

Keywords

wire drawing;die design;bimetallic forming;lubrication;reduction schedule

1. Introduction

Drawing Clad Welding Dimensions KeyProcessstep 。

**Fig. 1** Drawing Process Schematic Diagram

2. DrawingFundamentals

2.1 Bimetallic Deformation Coordination

**Fig. 2** Bimetallic Deformation Coordination Diagram

ε_core ≈ ε_clad = ln(A₀/A₁)

(1)

3. Design

Pass DesignWarrantyProductsquality Key。

4. Die Technology

**Fig. 3** Effect of Die Angle on Drawing Force

5. 6. Quality Control

7. Conclusion

Frequently Asked Questions

How does bimetallic drawing differ from single-metal drawing?

Bimetallic drawing requires consideration of deformation coordination between two metals. Due to different yield strengths of core and cladding, deformation may be uneven. Pass design and die parameters need optimization to ensure interface stress does not exceed bond strength and avoid delamination.

How to choose drawing die material?

Carbide dies are suitable for CCA and CCS, moderate cost, life 50-100km; Diamond dies are suitable for fine wires and high-precision products, life 100-200km but higher cost; Ceramic dies are suitable for high-temperature applications. Choose based on product specifications and production requirements.

How to control residual stress during drawing?

Residual stress originates from uneven deformation. Control methods include: optimizing pass reduction rate (15-25%), using appropriate die angle, maintaining good lubrication, controlling drawing speed. Residual stress can be eliminated by annealing.

Figures

Create Drawing ProcessDiagram

Fig. 1 Drawing ProcessDiagram

Dual MetalDeformation CoordinationDiagram

Fig. 2 Dual MetalDeformation CoordinationDiagram

Create DieAngle on DrawingForce Impact Curve

Fig. 3 DieAngle on DrawingForce Impact

Create Processing Hardening Curve

Fig. 4 Processing Hardening Curve

Create Residual Stress Distribution Diagram

Fig. 5 Residual Stress Distribution Diagram

Tables

Table 1 DrawingParameterScope

Parameter	CCA	CCS	NCC
PassReducedDiameterRate (%)	15-25	10-20	15-22
TotalReducedDiameterRate (%)	85-95	80-90	85-92
Drawing Speed (m/s)	1-5	0.5-3	1-4

Table 2 DieMaterialSelection

Die Type	ApplicableMaterial	Service Life (km)
HardQuality Alloy	CCA, CCS	50-100
Diamond	FineWire	100-200
High TemperatureApplications	30-50

Table 3 LubricantSelection

Lubricant Type	ApplicableMaterial	SpecialPoint
CCA	GoodLubrication
CCS	Cold EffectWell
Dry	NCC	CleaningProduction

References

Wistreich, J. G. The Fundamentals of Wire Drawing Metallurgical Reviews (1958)
ASM International Wire Drawing Handbook ASM (2019)

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