Abstract: As a core heating tube in household appliances,the insulation performance of electric heating tubes directly impacts the overall safety and reliability of the oven. Based on industry standards such as JB/T 4088—2022,systematically analyzes the influence of key materials and manufacturing processes on the insulation performance of embedded oven heating tubes under high-temperature operating conditions. Through specific failure case studies,combined with elemental analysis and experimental validation,it is identified that the silicone oil sealing process leads to the generation of free carbon due to high-temperature decomposition,significantly degrading the insulation performance of magnesium oxide（MgO）powder. The carbon content increased from 2.86% to 7.2%,resulting in a sharp decline in insulation resistance. The study further reveals the mechanism by which silicone oil infiltrates high-temperature zones due to negative pressure and uneven filling during the process. Improvement measures are proposed,including optimizing the sealing process and strictly controlling material purity and filling density. It is recommended to prioritize glass sealing in high-temperature applications to enhance long-term reliability. Provides practical guidance for the manufacturing and quality control of electric heating tubes,contributing to improved product safety and industry quality standards.

Key words: Heating element, Dielectric insulation performance, Silicone oil, Failure mechanism, Reliability