Total Productive Maintenance
Total productive maintenance (TPM) is more than simply a strategy. It is a thorough, all-encompassing philosophy with the goal of improving all aspects of a company’s production process. TPM encourages employees at all levels to “get to know the machinery” – familiarizing themselves with the way the equipment works and the production process so that problems can be quickly detected, maintenance tasks can be performed efficiently, and overall productivity and quality of items produced can be improved.
TPM incorporates other pre-existing maintenance strategies, especially predictive and preventive maintenance, as well as introducing a series of five fundamental organization tasks (known as the five Ss) and eight goals and areas of improvement (known as the eight pillars of TPM). Employees at all levels have a role to play, and the focus is placed on small, gradual, but continuous improvements in three areas: equipment availability, equipment performance and product quality.
A successful TPM strategy will result in significant improvements in overall equipment effectiveness (OEE). More products will be created in a shorter amount of time, with fewer defects, unplanned machinery stops, and other errors. Machines will be kept in top working condition at all times. In addition, many secondary benefits can be achieved, including increased employee morale, a greater sense of teamwork and unity within the company, and a safer, healthier environment with low to no risk of injury or illness.
This guide serves to explain in detail the steps needed to develop and implement a successful TPM approach for your company. With TPM, you can begin seeing improvements in no time!
History of Total Productive Maintenance
Total productive maintenance was developed by the Japanese maintenance consultant, scholar and author Seiichi Nakajima. In 1951, time-based and heavily scheduled preventive maintenance was introduced to Japan by maintenance experts from the United States, and was quickly adopted by members of the Toyota Group, such as the auto manufacturer Nippondenso. However, company leaders quickly found preventive maintenance to be expensive and inefficient, with maintenance tasks often being performed too frequently on machines which were actually functioning quite well.
Nakajima, an employee of the Japan Institute of Plant Maintenance, was therefore commissioned by the Toyota Group to develop a more time- and cost-efficient way of maintaining machinery. The result was total productive maintenance, which was successfully implemented by Nippondenso and later other Toyota Group members during the 1960s. Nakajima published a number of articles and books on the subject, in which he introduced key concepts such as the five Ss and eight pillars and coined now widely-used terms such as overall equipment effectiveness (OEE). For his work, Nakajima received a Medal of Honor for Public Service from the Emperor of Japan.
In 1986, English translations of Nakajima’s writings made their way to the United States. In the following years, TPM strategies were successfully introduced by a number of American companies in a wide variety of industries. Today, TPM sees frequent use in countries all over the world. Japan even hosts TPM Awards in memory of Seiichi Nakajima, which highlight particularly successful and innovative uses of his revolutionary philosophy.
Getting Started with Total Productive Maintenance
If you think that TPM might be right for your company, the first step is to establish goals. TPM is at its most successful when all employees are united and working towards a common objective. Start small – choose a few pieces of equipment to begin with, rather than attempting to apply TPM to every piece of machinery at once. Good choices for TPM are equipment pieces which are experiencing concrete, solvable problems such as slow production cycles or the frequent production of defective goods. Identify the problems, then use OEE calculations (outlined in the following section) to determine ideal production levels.
Once goals have been decided, it is time to introduce TPM to the entire company. Make sure from the very beginning that employees at all levels are engaged and have a role to play. Everyone from machine operators to top administrators are an important part of a successful TPM plan. Make schedules, assign specific tasks to specific employees. Divide employees into teams to begin tackling specific problems and investigating their root causes. Assign smaller maintenance tasks to the operators themselves, so that they can get to know their machines rather than calling in maintenance specialists for every problem.
It is important to implement every one of the five Ss and eight pillars of TPM which are described in the following sections. Ignoring any part of the overall TPM approach can lead to errors and delays in successfully improving production.
Calculating Overall Equipment Efficiency
The goal of overall equipment efficiency (OEE), as established by Seiichi Nakajima, is to establish “perfect production”. Equipment will always be operating at peak speeds with no downtime and create the maximum amount of products with zero defects. The majority of companies who have not implemented TPM are often functioning at a mere 40% OEE. Successful implementation of TPE can increase OEE significantly – TPM award-winning companies have reported OEE values of up to 85%.
The simplest equation used to calculate OEE is as follows:
Overall equipment efficiency = availability x performance x quality
To understand this calculation, it is necessary to break down the three factors which contribute to overall equipment efficiency.
Availability is, simply put, the amount of time during which the equipment is available to be used. An ideal availability score would be equal to the number of hours during which the company is open, i.e. the length of a standard workday. However, a number of factors can contribute to availability losses, including unplanned stops due to failure and planned stops due to maintenance or upgrading/replacing parts.
Performance is the speed at which a piece of machinery carries out its intended function, also referred to as production cycle. Performance speeds are different for each piece of equipment, and can range from a few minutes to a few hours depending on the nature of the goods being produced. Slow cycle times or small stops due to damage are the leading causes of performance loss.
Quality is the quality of the goods produced by the equipment. This refers both to how many units are produced and to how many units are produced which are defective and therefore must be discarded and cannot be sold. A high quality score means that the machinery is producing the maximum number of goods with zero defects. A reduced yield due to equipment failure can cause major quality loss, while defects are less common but also negatively effect quality score.
To calculate OEE, ensure that the equipment in question is operating in top condition (has been recently maintained, e.g. is clean and well-lubricated with no identified failures) and measure cycle speed (performance) and yield (quality) over a set period of time, usually one week. Multiply these totals by the length of a full work-week (one hundred percent availability) to determine a piece of equipment’s OEE.
An alternate way of looking at the the OEE equation in more quantitative terms is:
( Amount of Goods Produced During One Cycle x Fastest Cycle Time) / Planned Production Time = Overall Equipment Efficiency
Today, numerous software systems exist which can be used to determine OEE based on gathered data. This eliminates the need for the difficult and often unwieldy manual calculation of OEE totals.
The Five “Ss”: Core Principles of Total Production Management
The five Ss are a series of five simple tasks which should be regularly performed by employees to promote a clean, organized, and safe workspace. The five Ss are considered to be the foundation of a successful total production management plan, and should be carried out before moving on to any of the actions discussed in the eight pillars section below.
The five Ss were initially named in Japanese by Seiichi Nakajima as seiri, seiton, seiso, seiketsu and shitsuke. They have been translated into English in a number of different ways, with the most common rendering being sort, set in order, shine, standardize, and sustain. The tasks should always be carried out in that order.
- Sort – De-clutter the work area. Categorize each tool or part as vital or non-vital. Store non-vital parts somewhere easily accessible but away from the production area. A well-organized workspace improves employee and machine efficiency and decreases risks of injury or damage to the machinery.
- Set in order – Clearly label everything that remains in the workplace. Make sure that different categories of items – such as tools, cleaning equipment, etc. – are stored together in easy to reach areas. Throw away any and all trash near the equipment.
- Shine – Thoroughly clean all machinery and work areas. Dust, dirt, and grit is another major source of equipment damage. Lubricate equipment. Inspect high-wear areas such as bearings for any damage, and repair if needed. Disinfect any areas where hazardous chemicals or other dangerous substances are in use.
- Standardize – Document all of the above tasks and the manners in which they were performed. Make a note of which employees did what. Note names and brands of products or tools used in cleaning and organizing. Make sure employees are fitted with proper safety equipment (such as goggles or gloves) and that proper pre- and post-work hygiene procedures (washing hands, cleaning safety gear) are carried out. Take photos of the clean workspace so that employees will know how it is supposed to look.
- Sustain – Keep workspaces and equipment clean and organized at all times. Make schedules and assign roles to make sure that the sort, set and shine tasks are performed at frequent, regular intervals. Display photographs of clean workspaces and inventories of where tools should be properly stored.
The five Ss will serve as the first steps towards a cleaner, safer, more efficient workplace. Employees will begin to learn not only how to operate the machinery, but also how to clean and inspect it as well as performing small maintenance tasks such as lubrication and bearing inspection. Equipment will function more efficiently due to being kept clean and undergoing regular inspection. The risk of illness or injury will be lowered due to proper cleanup techniques and the use of safety gear being enforced at all times. Spills and any other accidents will be handled quickly, efficiently, and, most importantly, safely.
Once a schedule which incorporates all five of the above steps has been designed and successfully implemented over a period of at least several weeks, it is time to move on to the eight pillars of total production maintenance as described below.
The Eight Pillars of Total Production Maintenance
The eight pillars, alternately known as eight principles, of total production maintenance are a series of tasks and standards which should all be implemented to create the ideal TPM-centered workplace. The eight pillars synergize with one another to promote employee engagement and equipment efficiency while decreasing downtime, health or safety risks, and maintenance costs.
Each of the pillars is described in detail below. While they do not need to be implemented in this specific order, all eight should be included for a well-rounded TCM strategy which provides the greatest benefits and incorporates employees at all levels.
- Autonomous Maintenance. Regularly carrying out the tasks outlined in “the five Ss” above. Regular, small maintenance tasks such as cleaning, inspection and lubrication are carried out by the machine operators themselves. Machines are kept clean and workspaces organized at all times. Employees gain a greater familiarity with the machines they operate. The company saves money that would otherwise be used to hire expensive maintenance consultants and experiences less equipment downtime caused by unexpected failure.
- Planned Maintenance – Techniques of predictive and/or preventive maintenance are applied to monitor the equipment, gather data on its performance and anticipate failures before they occur. Condition monitoring equipment, such as the TactixTM vibration monitoring device by Proaxion, can be used to generate accurate, real-time data which is easy to read and interpret without necessitating any additional employee training. Any necessary downtime is carefully regulated and kept to a minimum, and machines experience longer overall lifetimes due to careful observation keeping them in top working condition. (To learn more about available predictive maintenance technologies, see here.)
- Quality Maintenance – When maintenance tasks are carried out, the purpose is not merely to fix the problem. Root cause analysis is performed to determine why production loss, slowed cycle time or other problems are occurring. Once a cause has been determined, a fix is developed and implemented as soon as possible. Data is shared with equipment manufacturers so that new versions of or upgrades to existing equipment can be performed to fix identified defects, which helps problems occur less frequently and reduces downtime even further.
- Focused Improvement – This draws from the Japanese philosophy known as kaizen, the idea that small, consistent, overall improvement in all areas of the production process should be prioritized over short term large improvements in one area which are often impossible to maintain. All employees work together towards the shared goal of improved production; employees at all levels are involved in the process of fixing problems and suggesting beneficial changes. Employee morale is increased and a greater sense of community is established.
- Early Equipment Management – All data gathered during the TPM process is analyzed and discussed with the purpose of improving the equipment. Communication is established between the producers of goods and the manufacturers of machines. Upgrades, updates and new versions of equipment are created with the goal in mind of fixing common problems and improving overall productivity. Machinery becomes more efficient and common, solvable problems are avoided or have a consistent solution method determined.
- Training and Education – Employees at all levels are trained and educated on the TPM process and their roles within it. This includes not only machine operators and maintenance specialists but management and administrative personnel. All employees gain greater understanding of how the machines are operated, how best to clean and inspect them, how to perform regular maintenance tasks, and how to interpret predictive maintenance data and analyze the root cause of failures. Employees begin to feel as though they are part of a team and that TPM and the improvement of OEE is a shared goal towards which they are all working together.
- Safe, Healthy Working Environment – All necessary improvements are made and precautions taken to establish a safe, health, workplace with a close to zero percent chance of accidents occurring. Employee training focuses heavily on safety and health standards and how to quickly and efficiently deal with problems such as spills. Safety gear is up to date and distributed to all employees who experience any safety or health risk while on the job. Cleaning materials are plenty and easy to locate. What accidents do occur are carefully recorded and analyzed to minimize the chance that they may happen in the future.
- TPM at the Administrative Level – Administrative employees are just as committed to and engaged in the TPM process as machine operators and maintenance staff. The five Ss are also applied to administrative offices – workspaces are kept clean, schedules are produced and cleanup tasks are carried out regularly. Work schedules for all departments are consistently kept up to date. Successes and improvements caused by the implementation of TPM are acknowledged and celebrated, further contributing to the improvement of employee morale.
It can take time to successfully implement all of the eight pillars of total production maintenance. However, the eight pillars, when correctly applied, will create a productive, efficient workplace filled with positive, high-achieving employees and with nearly zero risk of injuries or other accidents. Equipment will be producing as many high quality, defect free goods as possible in the shortest amount of time. Benefits such as a decrease in cost, time and labor needs will be seen in all areas of the organized to which the TPM philosophy has been applied.
Understanding Losses and Failures
During the initial implementation of TPM strategies, equipment losses and production failures will still occur. The goal of TPM is not only to fix these failures, but to ensure that they do not occur in the future. In order to carry that out, the first step is to identify which type of loss has occurred.
For this, we again turn to the three categories first introduced as components of the OEE equation.
Availability loss means any loss that completely shuts down the equipment for an extended length of time, so that no goods are produced whatsoever. Availability losses usually come in the form of unplanned stops due to equipment failure or planned stops due to adjusting the equipment, setting up the equipment, cleaning it or installing new parts.
Performance loss means that the speed at which goods are produced is slowed or delayed in any way. The most common types of performance loss include slowed cycle time due to equipment degradation, insufficient lubrication or wear on the bears or small stops which may be a sign of a larger problem or upcoming total equipment failure.
Quality loss is any decrease in the quality of the final product, i.e. the goods which the equipment is used to create. Quality loss is typically divided into decreased yield, in which the equipment is not producing enough goods (often occurring at the same time as a performance loss due to slowed cycle) and defects, in which the goods produced have visible or functional flaws and therefore cannot be used or sold.
Once the type of loss has been determined, it is important to identify where or in what part of the equipment the problem is occurring. This is known as a root cause analysis. For example, a conveyer belt which transports goods from one part of a workshop to another might slow down (performance loss) because of insufficient lubrication, because one of the moving parts within the belt has slowed or stopped, or for one of any number of other reasons. Software such as Proaxion®’s TactixTM vibration monitoring device can be used to aid in root cause analysis, as the device “listens” for what parts of the machine are emitting odd noises or experiencing irregular vibrations.
Once TPM has been successfully implemented, however, the amount of loss experienced will soon decrease noticeably as OEE increases. After only a short time of applying TPM techniques, your company will experience an increase in productivity employee morale, a decrease in accidents, equipment failures, and manufacturing costs, and the sense of accomplishment – shared by your entire team – that comes with knowing both you and your equipment are working towards achieving your highest potential.
Contact Proaxion® today to learn more about how predictive maintenance devices, such as the TactixTM vibration monitoring setup, can be a part of a successful TPM setup and contribute to rapid increases in overall equipment efficiency!