The Reliability of Magnetrons for Microwave Ovens

Abstract

AbstractProblems pertaining to the operation of magnetrons in microwave ovens have been identified using failure mode-effect analysis (FMEA) and other analytical techniques. Life test conditions have been established which tend to induce these failure modes. This investigation has focused on electron emission deterioration and vacuum leakage as two of the more crucial failure modes and different types of accelerated life tests were conducted. The results of the life tests revealed that under ordinary operating conditions the number of repeated intermittent operations greatly affects electron emission life. Although strap shape changes and breaking occurred under the rigorous conditions of the empty-oven life test, the strap was shown to have an adequate service life for ordinary application. The problem of vacuum leakage, which was found to occur under severe environmental conditions, has been resolved by improving the manufacturing method for magnetrons.From the life test results, the practical service life has been estimated at more than ten years, a figure that has been substantiated by field data.Key Words: Failure mode effect analysisFault tree analysisMicrowave ovenmagnetron Additional informationNotes on contributorsKitagawa KenjiDr. K. Kitagawa is a professor in the Faculty of Science and Engineering at the Science University of Tokyo, 2641 Yamazaki-Higashlkameyama, Nöda City, Chiba Pref., Japan. Y. Kanuma, T. Oguro and A. Harada are all with the Mobara Works, Hitachi Ltd., 3300 Hayano, Mobara City, Chiba Pref., Japan.Yoji KanumaDr. K. Kitagawa is a professor in the Faculty of Science and Engineering at the Science University of Tokyo, 2641 Yamazaki-Higashlkameyama, Nöda City, Chiba Pref., Japan. Y. Kanuma, T. Oguro and A. Harada are all with the Mobara Works, Hitachi Ltd., 3300 Hayano, Mobara City, Chiba Pref., Japan.Tomokatsu OguroDr. K. Kitagawa is a professor in the Faculty of Science and Engineering at the Science University of Tokyo, 2641 Yamazaki-Higashlkameyama, Nöda City, Chiba Pref., Japan. Y. Kanuma, T. Oguro and A. Harada are all with the Mobara Works, Hitachi Ltd., 3300 Hayano, Mobara City, Chiba Pref., Japan.Akikazu HaradaDr. K. Kitagawa is a professor in the Faculty of Science and Engineering at the Science University of Tokyo, 2641 Yamazaki-Higashlkameyama, Nöda City, Chiba Pref., Japan. Y. Kanuma, T. Oguro and A. Harada are all with the Mobara Works, Hitachi Ltd., 3300 Hayano, Mobara City, Chiba Pref., Japan.