The enamelling process on vertical ovens consists in the application of an electro-insulating enamel film on a copper or aluminium wire. This system is exclusively used for the production of medium, big and flat wire (0,50 - 5,00 mm for round fine wire up to 100 mm2).
The process phases are:
1) Bare wire annealing. Annealing is a process at high temperature which aim to soften the copper and make it more malleable.
2) Application of the enamel on the wire. This is a very important process of enameling; during this phase the wire is charged with enamel through an enameling die equipped with a calibrated slot that pour the quantity of enamel on the wire necessary to get a correct polymerization.
3) Enamel polymerization.The wire covered with the right quantity of liquid enamel is introduced then in the oven. There, it takes place the solvent evaporation phase and then the enamel polymerization one. Even if oven temperatures are setted on average 600 – 700 °C, due to the effect of wire speed, the enamel temperature reaches 250 – 300 °C. This phase last less than 1 sec. In last geneartions ovens. This process is repeated until the desideres thickness of enamel is reached.
4) Cooling of the wire. Thanks to big fans, cold air is driven on the wire to reduce the temperature under 100 °C.
5) Application of external lubricant. This process is really important to end users: in fact a well lubricated wire permits a good handiness during the production of motors windings.
6) Coils winding. Once is ended the wire enameling, the wire is assemblied in particular spools to be later on weighed and sold.