Welding

This post presents a review of a paper by a mill designer on the state-of-the-art of ring motor design in gearless drives. The conclusions in the paper are not justifiable. Ring motors are much more complex than grinding mills and the simple remedies offered in the paper would not have avoided most of the past failures. It is shown that external influences and design culture were the root causes of most of the ring motor problems since 1996 and the problems in design culture also exist in some mill vendor design groups. The conclusion in the reviewed paper that the ring motor failures are not diameter related is incorrect.