Raw material
Enamelled Copper Wire
Rod drawing → In-line annealing → Enamelling & curing → Lubrication, in-line testing & spooling
✓ Expert reviewed All content on this page has been reviewed by a senior motor engineer.
Process flow
4 main process steps, with the equipment and instruments used at each step, their main suppliers, and the technical control points.
- 1
Rod drawing
8 mm oxygen-free copper rod is drawn through successive diamond dies to the target diameter.
Technical control points:
- ▪Bare-conductor diameter — Within IEC 60317-0-1 tolerance (e.g. Ø0.50 ± 0.005 mm)Check: Laser gauge continuous; micrometer per spool
- ▪Surface quality — No scratches, slivers or copper fines (they become film faults)Check: Microscope check at each die change
- ▪Drawing lubricant — Concentration and temperature within spec; fines filteredCheck: Titration; daily
- 2
In-line annealing
Resistance annealing restores ductility after drawing.
Technical control points:
- ▪Elongation — ≥ IEC 60317 minimum for the size (≈ 30% for Ø0.5 mm)Check: Tensile test (IEC 60851-3); every spool
- ▪Springback — ≤ IEC 60851-3 limit — soft wire for tight windingCheck: Springback tester; per lot
- ▪Oxidation — Bright surface, no discoloration (steam / N₂ protection)Check: Visual; continuous
- 3
Enamelling & curing
Base coat (polyesterimide) and overcoat (polyamide-imide) are applied in many thin passes, each cured in the oven.
⚙ Enamelling Machine & Curing OvenAutomated- International
- To be added
- Mainland China
- To be added
Technical control points:
- ▪Film build — Increase within the IEC 60317-0-1 grade (e.g. Grade 2)Check: Overall-diameter gauge continuous; micrometer per spool
- ▪Oven profile vs. line speed — Inside the validated windowCheck: Oven thermocouples and speed log; continuous
- ▪Degree of cure — tan δ inflection temperature ≥ spec (e.g. ≥ 180 °C for class 200)Check: tan δ tester; per lot
- ▪Film concentricity — Min / max wall ratio ≥ 0.6Check: Cross-section under microscope; per lot
- 4
Lubrication, in-line testing & spooling
A surface lubricant is applied for winding, diameter and film faults are tested continuously, and wire is spooled.
⚙ In-line Diameter Gauge & HV Continuity TesterTest instrumentAutomated- International
- ZumbachShenzhen
- Mainland China
- To be added
Technical control points:
- ▪Overall diameter — ≤ IEC 60317-0-1 maximum for the gradeCheck: Laser gauge; continuous
- ▪Film faults (HV continuity) — ≤ IEC 60317 limit per 30 m for the gradeCheck: HV continuity tester (IEC 60851-5); continuous
- ▪Surface lubricant and friction — Coefficient of friction per winding requirement (needle winding needs low friction)Check: Friction tester; per lot
- ▪Spooling tension and layering — Per spool specification; no crossovers or loose turnsCheck: Tension controller continuous; visual per spool
Incoming inspection & approval tests
- Dimensions, elongation, springbackIEC 60851-2 / -3
- Flexibility and adherence (winding, jerk)IEC 60851-3
- Heat shock, cut-throughIEC 60851-6
- Breakdown voltage, film continuity (pinholes)IEC 60851-5
- Scrape and solvent resistanceIEC 60851-3 / -4
- Temperature index (thermal endurance)IEC 60172
Buyer FAQ
- Which enamel class do I need?
- Class 155 (polyurethane, solderable) for small low-temperature motors; class 180 polyesterimide for most industrial BLDC and stepper windings; class 200–220 with a polyamide-imide overcoat where higher temperature, abrasion resistance during winding or refrigerant resistance is needed.
- Grade 1 or grade 2 insulation build?
- Grade 2 (thicker film) gives higher breakdown voltage and fewer pinholes, and is standard for motors; grade 1 saves space where slot fill is critical and voltage is low. Check breakdown voltage and pinhole count per IEC 60851.
- How do I approve a new wire supplier?
- Ask for IEC 60317 type-test reports and the UL file, check 100 % in-line high-voltage continuity testing, and run a winding trial followed by surge testing — scraping and pinholes show up only on your winder.