Metal welding leader

Language

Home page

Welding Process for Copper‑Braided Wire and Copper Workpieces Using Medium‑Frequency Spot Welders

Aug 21,2026

Medium‑frequency spot‑welding of copper‑braided wire to copper workpieces is widely applied in high‑low‑voltage electrical apparatus, transformers and new‑energy electronic‑control equipment. It realizes lap conductive connections between copper‑braided wire and copper terminals, copper busbars and other copper parts. Braided wire consists of multiple fine copper strands with loose structure, abundant gaps and fast heat dissipation. Welding may produce strand fraying, strand blow‑off, surface over‑burning, internal cold joints, terminal overheating and insufficient tensile strength.

I Core Process Difficulties for Copper‑Braided Wire Welding

1.Loose structure prone to cold joints: Numerous gaps exist between copper strands with poor fitting. Welding heat disperses and local arcing occurs. Although surfaces appear welded, inner copper strands are not fully fused. Delamination, detachment and overheating may take place under equipment vibration.

2.Fast heat dissipation of copper makes heat accumulation difficult: Copper features high thermal conductivity. Heat dissipates rapidly in conventional welding, resulting in over‑burned and blackened surfaces while inner parts remain unfused, forming pseudo‑welds.

3.Fine copper strands have poor high‑temperature resistance and tend to fuse‑off: Thin braided copper strands cannot sustain high temperature. Slightly excessive heat input will blow strands apart, causing oxidation‑blackening and material embrittlement; finished workpieces crack easily upon bending.

4.Low contact resistance leads to tricky parameter tuning: Copper‑braided wire and copper workpieces conduct electricity fast with low resistance. Heat runs out of control readily, causing weld‑spot crushing, deformation and insufficient strength.

II Core Advantages of Medium‑Frequency Spot Welding for Copper‑Braided Wire

1.Stable current output enables short‑time concentrated heat build‑up to complete interface fusion rapidly without long‑duration high‑temperature damage to fine copper strands.

2.Supports complete sequence of pre‑pressing, pressure‑stabilized welding and pressure‑held cooling. Copper strands are pre‑compressed to eliminate gaps, fundamentally preventing cold joints, strand fraying and spring‑back deformation.

3.Achieves solid‑state metallurgical bonding between copper and copper without solder impurities. Weld spots feature low resistance and stable conductivity, resisting overheating and oxidation under long‑term heavy‑current operation.

III Pre‑Weld Preparation

1.Remove oil, dust, fingerprints and black oxide layers from welding zones to secure clean contact surfaces and avoid uneven resistance, local arcing and blackened cold joints.

2.Flatten and compress braided‑wire terminals before welding to eliminate bulges, lifted strands and loose gaps, prevent local suspension and fundamentally avoid cold joints and voids.

3.Fit braided wire centrally against copper workpieces with upright placement free of offset or one‑side suspension, securing even pressure and current coverage to avoid local over‑welding or incomplete fusion.

IV Welding Process Flow

1.Compress braided layers slowly to expel inter‑strand air, bring copper strands into tight contact with copper workpieces and stabilize contact resistance.

2.Apply low‑current pre‑heating to break oxide layers, prevent fine‑strand blow‑off caused by instantaneous heavy‑current impact and stabilize welding status.

3.Concentrate heat to finish rapid interface fusion, guarantee firm strand fusion and avoid strand burning, blackening and embrittlement induced by prolonged high temperature.

4.Implement continuous pressure‑held cooling after welding to counteract copper shrinkage discrepancy, release welding stress, prevent micro‑cracks and spring‑back loosening and improve weld‑spot strength and stability.

V Core Parameter Tuning Logic

1.Welding pressure: Insufficient pressure causes poor fitting, cold joints and arcing; excessive pressure crushes copper strands and renders material hard and brittle. Maintain even and stable pressure throughout the process to compress gaps without damaging wire strands.

2.Welding current: Adopt short‑duration peak current for instant forming and rapid termination of heat input, ensuring full fusion without strand burning.

3.Welding time: Longer welding time aggravates oxidation and embrittlement of copper strands. Minimize high‑temperature welding duration; rely on peak energy for fusion instead of extending time for strength gain.

4.Pressure‑holding time: Braided wire is flexible and prone to spring‑back loosening upon cooling. Sufficient pressure‑holding time locks weld‑spot structure and prevents delamination, micro‑cracks and strand fraying.

VI Common Defects and Root Causes

1.Cold joints, insufficient tensile strength and easy strand detachment: loose braided wire, un‑expelled gaps, insufficient heat input and contaminated surfaces.

2.Blackened weld spots, blown‑off copper strands and brittle material: excessive welding time, over‑abundant heat and over‑limit electrode temperature.

3.Post‑weld strand fraying and lifted edges with poor appearance: absent pre‑pressing, violent current impact and rapid pressure release after welding.

4.Weld spatter and copper chips: contaminated interfaces, gap‑induced arcing and excessively fast current rise.