This book introduces the metal magnetic memory (MMM) technique, one of the nondestructive testing methods, and its applications in remanufacturing engineering. It discusses the advantages of MMM and how to evaluate the early damage degree of remanufacturing cores, as well as the repairing quality of remanufactured components. Various MMM signal characteristics are extracted to reflect the damage degree of remanufacturing cores, coatings and interfaces. All the theoretical models, analysis methods and testing results of MMM in this book provide guidance to control the quality of remanufactured parts and products. This book can help readers make the best use of the MMM technique in remanufacturing engineering.