Total Preventive Maintenance (TPM) is a production management approach that places the responsibility for routine maintenance on the workers who operate the machinery, rather then employing separate maintenance personnel for that function. Used in many Japanese companies, TPM gives employees "a sense of responsibility and awareness of the equipment they use and [cuts] down on abuse and misuse of the equipment," William J. Stevenson wrote in his book Production/Operations Management. TPM is increasingly being used in manufacturing environments in the United States. It holds particular appeal for small manufacturers.
The term maintenance is used to describe the various efforts businesses make toward keeping their facilities and equipment in good working order. It encompasses both breakdown maintenance—a policy that involves dealing with problems as they occur and attempting to reduce their impact on operations—and preventive maintenance—a policy that involves using such measures as inspecting, cleaning, adjusting, and replacing worn parts to prevent breakdowns from occurring in the first place.
Preventive maintenance is performed periodically in order to reduce the incidence of equipment failure and the costs associated with it. These costs include disrupted production schedules, idled workers, loss of output, and damage to products or other equipment. Preventive maintenance can be scheduled to avoid interfering with production. Common methods of planning preventive maintenance are based on the passage of time, on the amount of usage the equipment receives, and on an as-needed basis when problems are uncovered through inspections. Ideally, preventive maintenance will take place just before failure occurs in order to maximize the time that equipment is in use between scheduled maintenance activities.
As Stevenson explained, the goal for production managers is to find a balance between preventive maintenance and breakdown maintenance that will minimize the company's overall maintenance costs. "Decision makers try to make a trade-off between these two basic options that will minimize their combined cost," he noted. "With no preventive maintenance, breakdown and repair costs would be tremendous. Furthermore, hidden costs, such as lost production and the cost of wages while equipment is not in service, must be factored in. So must the cost of injuries or damage to other equipment and facilities or to other units in production. However, beyond a certain point, the cost of preventive maintenance exceeds the benefit."
The decision of how much maintenance to perform involves the age and condition of the equipment, the complexity of technology used, the type of production process, and other factors. For example, managers would tend to perform more preventive maintenance on older machines because new ones have only a slight risk of breakdown and need less work to stay in good condition. It is also important to perform routine maintenance prior to beginning a particularly large or important production run.
In TPM, production employees are trained in both operating procedures and routine maintenance of equipment. They perform regular inspections of the machinery they operate and replace parts that have become worn through use before they fail. Since the production employees spend so much time working with the equipment, they are likely to pick up small signals that a machine is in need of maintenance. Among the main benefits of TPM is that employees gain a more complete understanding of the functioning of the system. TPM also gives them increased input into their own productivity and the quality of their work.