Total Productive Maintenance
TPM is implemented as part of the IMPROVE phase in a DMAIC Six Sigma project. However, its purpose is to control the inputs (to allow stable output) in projects where the process is dependent on:
Performance (how well the machine runs when it is running)
As you recall, these are the three factors that make up OEE, Overall Equipment Effectiveness. OEE is often used as a lagging indicator metric to gauge a TPM program. TPM is a critical principle for Lean manufacturing. If machine uptime (availability) is not predictable and product can not flow smoothly and reliably then there will be inventory and buffers must be kept to protect the customer.
Excess Inventory is waste, it ties up cash, takes up space, and may have shelf life. TPM has many other names such as Total Predictive Maintenance, Total Process Management, Total Preventive Maintenance, and others but they are all slightly unique and components of Total Productive Maintenance.
Preventing downtime and errors is important and there are many tools such as NVH monitoring, infrared image surveying, ultrasonic tests, that can predict failures before they actually occur to keep machines “available” when they are needed.
A robust preventive maintenance program is also key to a TPM program. Tracking and executing according the PM manuals are inputs to preventing unplanned downtime and quality defects. Similar to regular oil changes and tire rotations on a vehicle.
Summary of TPM
TPM was developed in the 1970’s as a method of involving machine operators in the preventive maintenance of their machines – a reaction to increasing specialization and centralization of the maintenance function that had created division-of-labor barriers between operators and the maintenance of their machines and equipment.
Autonomous maintenance activities tap the knowledge and skill of the people who work with the equipment on a daily basis, and gives operators a stake in the performance of the equipment. This involvement is part of a larger philosophy of continuous improvement, or Kaizen, that touches all shop floor activities. Involving machine operators also makes the regular maintenance people more productive by focusing them on more extensive preventive maintenance (PM) tasks.
The overriding objective of TPM is the elimination of LOSSES. Losses, or waste, includes equipment downtime, defects, scrap, accidents, wasted energy, and labor inefficiency.
Equipment reliability is a cornerstone of a lean production system. With little or no buffer inventories, equipment failures directly impact production volumes and customer service, so effective preventive maintenance is a critical activity. By bringing together people from all departments concerned with equipment into a comprehensive PM system, equipment effectiveness is raised to the highest possible level.
Most TPM programs are built upon autonomous small group activities – the people closest to the action. This requires the support and cooperation of everyone from top management on down.
Benefits of effective TPM include the following:
Safer Working Environment
Improved Equipment Reliability – Uptime
Company Financial Performance and Job Security
Core Elements of TPM
There are five core elements to a TPM program:
Operator Self-Maintenance – Basic program of cleaning, lubrication, general inspection, and minor preventive maintenance to be completed by production operators (associates).
Conduct Planned Maintenance – Develop and execute planned maintenance activities. Establish standards for each piece of equipment, prioritize equipment based on relative importance to safety, quality, productivity and cost. Establish a maintenance plan for each piece of equipment – may be based on time, condition, overhaul, or predictive maintenance.
Small Group Kaizen Activities – Team activities that focus on eliminating losses by focusing on all elements of OEE. The 5-Why analysis is often used to guide small group actions.
Education and Training – All employees must be systematically trained to provide awareness and improve skill levels.
Maintenance Prevention – Early equipment management is a system whereby shop-floor personnel participate in the new equipment concept and design phase to develop equipment that requires less maintenance, and is more easily maintained when maintenance is required. As with all processes, the most leverage to effect change exists in the design phase.