Cause Analysis and Process Optimization of Insulation Delamination and Bulging of Aerospace Wires

The lapping-extrusion composite insulation is a critical structure for aerospace wires to achieve high voltage resistance, high corona inception voltage, excellent sealing performance, and high reliability. Aiming at common defects including insulation delamination, bulging, and poor appearance occurring during the manufacturing of such structures, this paper takes aerospace wires with 10 mm² silver-plated copper conductors, PI/PTFE composite tape-lapped inner insulation, and PFA extruded outer insulation as the research object. Systematic analysis is conducted from perspectives of material properties and manufacturing processes. It is concluded that improper control of lapping tension and lapping angle, insufficient drying of the wire core prior to extrusion, and inappropriate cooling conditions after PFA extrusion are the primary causes leading to delamination and bulging of composite insulation.By optimizing the composite tape lapping process (tape tension: 2.5 N/mm² ± 0.1 N/mm², lapping angle: 68° ± 2°, with an additional auxiliary straightening device) and the PFA extrusion process (preposed cooling water diversion, enhanced drying system), multi-batch production verification shows that the optimized process effectively suppresses insulation delamination and bulging. The appearance and comprehensive performance of finished products fully meet the requirements of military standards GJB 773B-2015, GJB 973B-2021, and other relevant specifications.