Use of Nontraditional Temperatures on Aluminum Caged Centrifuged Rotors Annealing—Assessment of the Viability and Effectiveness in Reducing Interbar Losses

Abstract

Due to differences in the manufacturing process, centrifuged rotors have higher efficiency and interbar resistance than those produced by the high-pressure die-casting process. Therefore, the annealing applied to high-pressure die casted rotors to improve the insulation of the cage is not traditionally applied by manufacturers to centrifuged rotors. This study evaluates the effect of the traditional 450 °C heat treatment on centrifuged rotors, as well as the feasibility and effects of 520 oC rotor annealing, temperature not recommended for high-pressure die-casted rotors. The efficiency measurements were performed with a dynamometer, using small single-phase motors, usually applied in domestic refrigeration compressors, with a standard stator kept under controlled conditions. A structured test was performed to assess the effects in a mass production scenario, aiming to reflect the variation of the production parameters within the manufacturer specifications.