Manufacturing
Production Process for Enameled WireFrom Copper Rod to Precision-Coated Conductor
Over 500 pieces of state-of-the-art machinery — wire drawing, enameling, stranding, and wrapping — backed by a skilled team of professionals.
Enameled wire manufacturing transforms high-purity copper rod into precision-coated conductor through a multi-stage process. Each stage is tightly controlled — from the initial 8 mm rod down to ultrafine gauges as small as 0.008 mm, coated with polymer insulation that must withstand temperatures from 130 °C to over 240 °C depending on the application.
The process divides into two main phases: wire drawing (reducing the copper rod to the target conductor diameter) and enameling (applying and curing multiple layers of insulating polymer). Quality control runs continuously throughout both phases.
Phase 1
Wire Drawing
Production begins with an 8 mm diameter copper rod, drawn through a series of progressively smaller dies across multiple machine groups. Each group is designed for a specific diameter range. The wire gets thinner and longer with each pass while total mass remains constant.
Drawing dies are engineered with natural or synthetic diamond for fine wire, and tungsten carbide for larger diameters. Rod and dies are flooded with coolant and synthetic lubricant to extend die life and maintain surface quality. The resulting bare wire is cold-worked — hard and brittle — requiring annealing before enameling.
Phase 2
Enameling Line
The drawn wire enters a continuous enameling line — annealed, coated, cured, cooled, lubricated, tested, and spooled in a single pass. The coating-and-curing cycle is the heart of the process: each pass deposits one thin layer, and a typical wire receives 6–20 individual layers for superior strength and dielectric performance.
10 Stages from Rod to Finished Wire
Stages 4–6 repeat multiple times per pass — each cycle applies and cures one thin enamel layer.
Copper Rod Production
Electrolytic copper cathodes are smelted in a reflection furnace, continuously cast, and rolled into 8 mm diameter rod. YIDA exclusively uses ETP1 grade copper with a minimum purity of 99.99%, sourced from select, quality-assured suppliers.
Wire Drawing
The 8 mm copper rod is drawn through a series of progressively smaller dies — natural or synthetic diamond for fine wire, tungsten carbide for heavier gauges — to achieve diameters as fine as 0.008 mm. Coolant and synthetic lubricant extend die life and prevent overheating.
Annealing
Cold-worked wire from the drawing process is heated under a protective atmosphere (~300 °C) to recrystallize the copper grain structure, restoring softness and ductility. This also burns off residual drawing lubricant and ensures a clean, oxide-free surface for enamel adhesion.
Enamel Coating
Liquid insulating varnish is applied via felt pads (fine wire) or precision dies (heavy wire). The key principle: many thin layers rather than fewer thick ones. A typical wire receives 6–20 individual enamel layers, building up the total insulation thickness gradually for superior mechanical and electrical integrity.
Curing
After each coat, the wire passes through a temperature-regulated oven at 250–300 °C. Solvents evaporate and are destroyed via catalytic combustion, while the polymer crosslinks into a hard, adherent insulating film. The coating-and-curing cycle repeats for every layer.
Cooling
Purified, filtered air is blown countercurrent through cooling ducts to bring the wire temperature down gradually. Controlled cooling prevents thermal shock and enamel cracking — no direct water cooling is used.
Lubrication
A precisely controlled amount of paraffin-based lubricant is applied to the finished enamel surface, enabling smooth high-speed winding onto bobbins and coils without wire breakage or surface damage.
In-Line Quality Control
Laser gauges continuously measure outer diameter for dimensional tolerance. Spark testers apply high voltage (350–3,000 V depending on gauge) to detect pinholes in the insulation in real time. Tension is monitored to prevent elongation.
Spooling
Winding pitch and spool rotational speed are precisely regulated to ensure the wire can be de-reeled smoothly in downstream operations without tangling or trapping.
Final Testing
Finished wire undergoes breakdown voltage testing, pinhole count, adhesion and flexibility tests, electrical resistance measurement, and insulation thickness verification against IEC 60317, NEMA MW 1000C, and JIS C3202 standards.