The so-called PM is an abbreviation of the initials of Preventive Maintenance and Productive Maintenance, and is defined as follows in the PM Glossary of the Japan Society of Plant Engineering. -It is the most economical maintenance method to improve the productivity of equipment. It aims to improve the productivity of a company by reducing all maintenance costs related to the use of equipment, such as the value of the equipment itself and maintenance, as well as all costs related to the loss of equipment due to its deterioration, from the entire process of designing, manufacturing, using, and maintaining the equipment, in other words, over the lifetime of the equipment. As its means, there are preventive maintenance, maintenance after the fact, improvement maintenance and maintenance prevention.
When PM was first introduced in China (around 1951), it was called "Preventive Maintenance" for the activity of preventing equipment failures in advance, and then, around 1954, since the U.S. GE society placed special emphasis on the improvement of production efficiency, i.e., since it advocated production maintenance, which means money-making maintenance, PM has Since then, around 1954, when GE in the U.S. emphasized the improvement of production efficiency, PM has become a term with two meanings, and today, PM simply means "productive maintenance. Regarding "preventive maintenance", the word "preventive maintenance" is often used in Japanese.