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Differences Between Square‑Forming and Spot‑Welding of Copper‑Braided Wires and Tinned‑Copper Wires by Medium‑Frequency Spot‑Welders
Sep 07,2026
In the production of new‑energy flexible connections, automotive wire harnesses and high‑low‑voltage electrical accessories, copper‑braided wires and tinned‑copper wires feature similar appearance and applications, yet great differences in surface‑layer material properties. Medium‑frequency spot‑welding processes cannot be interchanged.
I Root Causes for Process Differences
Copper‑braided wire has no surface plating, featuring high melting point, uniform texture, high temperature resistance and compression‑wear resistance. It resists flow‑induced deformation under pressure; no plating melting and loss occur upon heating with stable structure. Square‑forming and welding processes enjoy wide parameter tolerance. Welded joints achieve sound fusion and stable internal resistance.
Tinned‑copper wire is covered by a tin plating layer. Tin is soft with low melting point. It flows and overflows easily under pressure and melts rapidly at high temperature. Square‑forming tends to generate tin accumulation and loose strands; welding may produce tin spattering, interlayers and cold joints.
II Process Differences and Common Defects in Square‑Forming
1.Square‑forming characteristics of copper‑braided wire
Copper‑wire surfaces provide high friction; strands resist sliding and dislocation for good forming stability. Conventional pressure and steady downward pressing can be adopted. Its main function is to compress gaps among wire harnesses and smooth braided textures, compressing loose wires into flat and compact integral structures.
Common defects are mostly inner‑layer gaps and insufficient compaction caused by insufficient pressure, or local strand breakage and wire deformation caused by excessive pressure. Spill‑over material and peeling hardly occur.
2.Square‑forming characteristics of tinned‑copper wire
Slightly higher pressure squeezes out surface tin plating, generating edge tin accumulation, local tin shortage and loose‑strand offset. It also causes uneven wire thickness and local copper exposure, losing anti‑corrosion and anti‑oxidation performance and directly undermining subsequent welding stability.
Common defects: tin spill‑over agglomeration, tin‑layer peeling, uneven forming, loose wire ends.
III Process Differences and Common Defects in Medium‑Frequency Spot‑Welding
1.Spot‑welding features of copper‑braided wire
Free of plating barrier and with good high‑temperature resistance, copper wires achieve sufficient fusion under proper heat input to form dense and firm weld spots. Moderate heat input and stabilized pressure can be adopted to guarantee thorough inter‑strand fusion.
2.Spot‑welding features of tinned‑copper wire
Slightly excessive welding heat will make massive molten tin overflow and accumulate around weld spots, forming tin interlayers which hinder copper‑wire fusion and result in pseudo‑welds.
Molten tin tends to adhere to electrodes, generating tin buildup nodules, which cause unstable welding current, spattering and dark‑colored weld spots in subsequent welding cycles.
IV Key Process Points for Two Types of Wires
1.Process for copper‑braided wire
Adopt medium‑pressure steady‑speed forming to moderately compress harness gaps and obtain flat and compact cross‑sections. Apply moderate heat input and stabilized pressure in welding to realize sufficient multi‑strand copper‑wire fusion, eliminate inner‑layer cold joints and improve weld‑spot strength and stability.
2.Process for tinned‑copper wire
For square‑forming: adopt low‑pressure slow‑speed gentle forming. Avoid high‑pressure impact which squeezes away tin plating and breaks strands.
For spot‑welding: adopt low‑temperature short‑time fusion and light‑pressure fitting without tin squeezing. Prevent tin overflow and inter‑layer cold joints, preserve plating integrity to guarantee firm and non‑heating weld spots.
Wuxi Haifei Intelligent Equipment Co., Ltd. https://www.haifeiwelder.com/
Wuxi Haifei Intelligent Equipment Co., Ltd. has been focusing on the R&D and production of spot‑welding machines for 17 years. The company has obtained ISO9001 Quality Management System Certification, China Compulsory Certification (3C) and CE Certification. It is a National High‑tech Enterprise, a Specialized, Refined, Differential and Innovative Enterprise of Jiangsu Province, a Specialized, Refined, Differential and Innovative Enterprise of Wuxi, and a Gazelle Enterprise in the Southern Jiangsu National Self‑Dependent Innovation Demonstration Zone.
Should you be interested in our spot‑welding machines, please contact us: 400‑0510‑750.
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Wuxi HAIFEI Intelligent Equipment Co., Ltd.
Wuxi HAIFEI Welding Equipment Co., Ltd.
Add: 28 Shuiyun Road, Yuecheng, Jiangyin, Jiangsu Province, China. (Postal Code: 214404)
Mobile: +86 18915302352
Email: wushijie@jshaifei.com