The state of the art of magnet wire manufacturing process is the application of liquid enamel (varnish) on a drawn conductive material. First of all, the wire is drawn to the required conductor dimension. After the drawing, the wire is annealed in order to restore mechanical properties for further processing. The enamelling process consists of enamel application, curing and cooling. First of all, the bare annealed conductor passes through a bath with liquid enamel. Due to its high viscosity, a thick film forms on the wire. After that, the wire passes through an enamelling die with specified cross-section. The gap between the conductor and the die delivers the enamel increase per one pass. Subsequently, the wire passes through the curing oven, where at a temperature of approx. 600 °C the organic solvents evaporate from the liquid enamel, creating a compact, solid insulating layer. After the cooling of the wire, the process is repeated over and over again until the required insulation thickness is reached. Before the coated wire is wound onto a spool, the wire passes through an inline measurement device, where every inch of produced wire is tested for surface imperfections and discontinuity of insulation.

Depending on the material type, diameter, cross-section of enamel thickness, vertical (built in towers approx. 30m high) and horizontal lines are in use. Despite the fact that the basic principal of a cyclic application of liquid enamel with subsequent curing hasn’t changed since decades, the modern machines work much more efficiently, productively, are significantly more environmentally friendly and they are fully integrated into the industrial infrastructure of the 21st century.

The first industrially available alternative to the enamelled copper wire seems to be an extruded PEEK magnet wire. Here the conductor is covered with one single layer of a high performance polymer (in this case PEEK – Polyetheretherketon). 

Although these wires are not standardized yet and they are on the market only since a couple of years, they are being utilized in some rare high performance applications. They are popular due to their outstanding chemical and mechanical resistance, which is, together with high applicable thicknesses and surface nearly free of any imperfection a good premise for high performance applications. On the other hand, optimized enamel wires are already comparable with extruded wires. Last but not least, for relatively small performance step forward, significantly higher price must be paid (price factor of approx. 3 – 5 times over magnet wires)

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