Microscopical Morphology Characterization and Formation Cause Analysis of Common Appearance Defects in Enameled Copper Wire

Common appearance defects on enameled copper wire, such as particles and paint film scratches, seriously compromise the safety and reliability of electrical products. This study aimed to investigate the fundamental formation mechanisms of these defects to guide process optimization. The micro-morphologies and elemental compositions of solid particles, continuous particles, and paint film scratches on 0.5~2.0 mm enameled copper wires were characterized using Laser Scanning Confocal Microscopy (LSCM) and Field Emission Scanning Electron Microscopy (FESEM), and the formation causes were traced by correlating the analytical results with actual production conditions. It was found that solid particles originated from the adhesion of contaminants, such as tar from the oven outlet, onto the bare copper wire; continuous particles were caused by the vibration of the coating die, which was induced by an insufficient paint liquid level, leading to local paint accumulation; and paint film scratches were primarily attributed to the rolling and crushing of hard foreign objects attached to the guide wheels. The study demonstrated that microscopic analysis is an effective method for linking defect morphology to production parameters, and the formation mechanisms of the three defect types were elucidated, providing a direct theoretical basis and technical support for developing targeted process improvements and enhancing product quality.