After the insulating paint has been applied to the cond […]
After the insulating paint has been applied to the conductor, the solvent and the diluent are first evaporated in the baking process. There are two forms of liquid into gas: evaporation and boiling. Liquid surface molecules into the air is called evaporation, it can be carried out at any temperature, the temperature and density, high temperature and low density can make evaporation speed up. When the density reaches a certain amount, the liquid is no longer evaporated and becomes saturated. The molecules inside the liquid become gas to form bubbles rise to the surface of the liquid, the bubbles burst to release the vapor, and the phenomenon that the molecules inside and outside the liquid vaporize at the same time is called boiling.
Enameled paint film requires smooth, solvent vaporization must be carried out in the form of evaporation, the absolute does not allow boiling, or enameled wire surface will produce bubbles and hair. With the evaporation of the solvent in the paint liquid, the insulating paint becomes thicker and the solvent inside the paint liquid migrates to the surface for a longer time, especially the thick enameled wire. Due to the thick coating liquid, the evaporation time needs to be lengthened to avoid the solvent Gasification phenomenon, get a smooth film.
Oven evaporation zone temperature, depending on the boiling point of the solution, low boiling point evaporation zone temperature is lower. However, the temperature of the paint liquid on the surface of the wire is transmitted from the temperature of the furnace, together with the endothermic heat of the solution evaporation and the heat absorption of the wire. Therefore, the temperature of the paint liquid on the surface of the wire is much lower than the temperature of the paint.
This is because the wire coating after the formation of a uniform layer of paint on the wire, if not quickly baked into the film, due to the surface tension of the liquid paint and wetting angle caused by the role of shrinkage, when the evaporation zone temperature is low paint temperature low solvent evaporation time is long, paint liquid mobility in solvent evaporation is small, poor leveling, when the evaporation zone temperature is high, the temperature of the paint liquid is high, the solvent evaporation time is short, paint liquid movement in the solvent evaporation Sex, good leveling, enameled wire surface is smooth.