Enameled Flat Copper Wire

Enameled flat copper wire is a high-performance magnet wire designed for high-density, high-efficiency winding applications. It features a flat rectangular conductor made of ≥99.97% oxygen-free copper, coated with 5–13 layers of insulating varnish cured by mould or felt method. With ±1μm dimensional accuracy, it achieves a slot fill factor of 70–75% (25–30% higher than round wire), making it the ideal choice for new energy vehicle (EV) traction motors, traction motors, wind power generators and large dry-type transformers.

JWHK is one of the few Chinese manufacturers capable of mass-producing EV-grade flat copper wire, with an annual capacity of 8,000 tons and stable supply to global automotive and electrical equipment manufacturers.

Key Technical Indicators:

• Copper purity: ≥99.97%
• Conductivity: 58 MS/m
• Dimensional tolerance: ±1μm (width & thickness)
• Slot fill factor: 70–75% (vs 45–55% for round wire)
• Insulation breakdown voltage: ≥6kV/0.1mm
• Thermal cycle resistance: -40℃ to 200℃, 1000 cycles no insulation failure

1 Flat vs Round Wire: Quantified Efficiency Boost

• Core Formula: Slot Fill Factor = (Total Conductor Cross-Section Area ÷ Stator Slot Area) × 100%

• Application Impact: For EV motors, this means longer driving range, faster acceleration and smaller battery size.

 2. Scenario-Based Selection Guide

Scenario 1: New Energy Vehicle Traction Motors

• Buyer Pain Points: High vibration, frequent thermal cycles, high power density requirements, strict quality consistency
• JWHK Solution: Class 200 EI/AIW Enameled Flat Copper Wire

99.97% high-purity copper, low high-frequency loss

Class 200 insulation, withstands -40℃ to 200℃ thermal cycles

5–13 layers of uniform insulation, excellent wear resistance under vibration

±1μm precision, perfect fit for automated hairpin winding lines

Scenario 2: Large Dry-Type Transformers

• Buyer Pain Points: Low eddy current loss, long service life, stable insulation performance
• JWHK Solution: Class 180 EIW Enameled Flat Copper Wire

High slot fill factor reduces transformer size and weight

Low eddy current loss improves energy efficiency

Excellent thermal stability, 20+ year service life

3. Purity & Efficiency Correlation

4. ±1μm Precision: Production Yield Guarantee

• Industry Problem: ±3–5μm tolerance causes winding misalignment, insulation damage and 10–15% rework rate
• JWHK Solution: French REDEX precision rolling mill + AI online monitoring

Dimensional accuracy: ±1μm

2D bump detection, non-contact length measurement (±0.05% accuracy)

Batch CPK ≥1.33

Customer Benefit: Winding yield increased to 99.8%, eliminating rework costs for mass production

Stage 1: Bare Flat Copper Wire Preparation

 

1. Raw Material Preparation (Self-Produced Up-Cast OFC Rods)

￮ Core Equipment: Self-developed up-cast continuous casting unit
￮ Key Parameters: Copper purity ≥99.97%, oxygen content ≤15ppm, resistance unbalance rate ≤0.4%
￮ Quality Control: Spectral analysis per furnace; unqualified materials are rejected

2. Extrusion & Multi-Die Drawing

￮ Core Equipment: 1250-ton hydraulic extruder + 8-block wire drawing machine
￮ Key Parameters: Extrusion temperature 850–900℃, 8-stage drawing, single-pass reduction rate 15–25%
￮ Quality Control: Online dimension monitoring; surface flaw detection after drawing

3. Precision Rolling (French REDEX Mill with Integrated Grinder)

￮ Core Advantage: Exclusive EV-grade production technology
￮ Key Parameters: Rolling speed up to 400m/min (4× conventional equipment), dimensional tolerance ±1μm, surface roughness Ra ≤0.2μm
￮ Quality Benefit: Dense microstructure, minimal edge burrs, batch CPK ≥1.33

Stage 2: Enameling Process (Austrian MAG EV-Grade Line)

 

￮ Key Parameters: 5–13 varnish coats, zone-controlled curing temperature 350–420℃, line speed 80–200m/min
￮ Process Control: Uniform insulation thickness, strong adhesion, thermal cycle resistance -40℃ to 200℃
￮ Quality Control: Breakdown voltage testing every 20 minutes; thermal shock testing per batch

Stage 3: AI Online Inspection System (EV-Grade Standard)

 

￮ Configuration: 6 high-resolution cameras + 3D laser measurement
￮ Detectable Defects: Particles, scratches, bubbles, embossing, edge burrs and foreign matter
￮ Performance: Missed detection rate <0.5%, false positive rate <0.5%
￮ Traceability: Full process data recording per batch; unique identification for each coil

Stage 4: Final Testing & Packaging

 

￮ Full performance testing including conductivity, breakdown voltage, flexibility and thermal shock
￮ Heavy-duty export packaging with moisture-proof and anti-collision protection

• Delivery Commitment: Standard order 2–4 weeks, urgent order 1–2 weeks priority production.

Spools: Heavy-duty wooden spools

Outer Packaging: IPPC wooden pallets, reinforced wooden crates

Protection: Moisture-proof film, foam cushioning, steel strapping

Shipping: Sea, air, land; global door-to-door service available

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