Production of low impurity aluminium rotor for motor efficiency enhancement Savitri Payakkapol, Nattapon Chayopitak, Panya Kunsuwan, Naoto Ohtake and Sompong Srimanosaowapak MATEC Web Conf., 192 (2018) 01043 Published online: 14 August 2018 DOI: 10.1051/matecconf/201819201043