It is understood perfectly by the name TPM (total productive maintenance) i.e. “A maintenance Strategy aimed at to maximize plant and equipment effectiveness to achieve optimum life cycle cost of production equipment, or in other words, keeping equipment in a position to produce at maximum capacity, the expected quality products, with no unscheduled stops which includes zero breakdowns, zero downtimes, and maximum production efficiency.”
TPM is an innovative Japanese concept. The origin of TPM can be traced back to 1951 when preventive maintenance was introduced in Japan. The ideas of TQM (Total Quality Management) and the concepts of PM (Preventive Maintenance) were only partial answers to the issues of maintenance and quality. After much trial and error, the PM effort evolved into TPM.
TPM was the brainchild of Toyota. It was based on a component of the Toyota Production System (TPS). TPS is designed for a particular time, circumstance, and place. It was designed by people in tune with their culture and organization. TPS was specifically designed to manage the assembly of automobiles.
TPM, TQM (total quality management), Lean manufacturing, Lean maintenance, and JIT form the basis of the Toyota Production System (TPS). All of the programs support each other and the company produces high-quality products with very few inputs and very less waste.
THE TPS HOUSE
The TPS House is a very simple representation but the most recognizable symbol in the Toyota Production System (TPS) that Toyota developed to teach its supply base the principles of the TPS. The foundation base of the house represents operational stability and has several components, one of which is Total Productive Maintenance.”
Terms of TPM (Total Productive Maintenance)
There are several terms used in Toyota Production System (TPS). These terms are very useful for understanding the TPM, TPS or Lean Manufacturing. Some important terms are as follows:
Availability: The actual run time of a machine as a percentage of its planned run time.
Best of the Best: An OEE figure calculated by multiplying the best weekly availability, the best weekly performance and the best weekly quality rates for a machine over a period, e.g. of typically one month.
5S: Five common sense principles of workplace organization (arrangement, neatness, cleaning, order, and discipline). CAN DO is the western equivalent of the Japanese 5Ss.
Condition Cycle: The second stage of the TPM Improvement Plan, which includes criticality assessment, condition appraisal, refurbishment plan, and the asset care program.
Condition Appraisal: The assessment of the condition of a machine’s components as a first step to undertaking the refurbishment plan and improving the OEE. This must involve carrying out a deep clean as part of the assessment.
Measurement Cycle: The first stage of a TPM Improvement Plan, consisting of collecting equipment history, calculating the OEE and assessing the Six Losses.
Minor Stoppage: When a machine is stopped for a relatively short period (e.g. to clear a blockage) and then re-started without the need for any repair. A minor stop, therefore, causes an Operator to have to interfere with the
process, but does not require the attendance of a Maintenance Technician.
Five Whys: Asking ‘Why?‘ five times to try to get to the root cause of the problem.
Criticality Assessment: An evaluation of each of the machine’s components against set criteria and their likely impact on production, safety, environment, and cost.
Four Milestones: This is the progression the organization goes through over a period of approximately 4-6 years as they embark on the TPM Process. These have been recognized as discrete phases that organizations go through as they transform themselves. The 4 Milestones are:
2. Refine Best Practice and Standardize
3. Build Capability
4. Zero Losses
At each Milestone, there will be audits to establish your capability in transforming the business and further planning to take into account the future changes required to meet customer and market needs, as well as the organization’s needs. For each milestone, your management team will have defined goals and targets as Pillar Champions, which should be realized having reached each of the milestone stages.
Improvement Zone (IZ): This is a geographical area where the First Line Managers and their teams apply the basic techniques of TPM and CANDO/ 5s. This area is manageable but the representative portion of the process, or
the plant which when improved, will provide an important contribution to the business.
Maintainability: This refers to how easy it is to gain access to the equipment and the particular skills needed to diagnose a problem.
Nine Step TPM Improvement Plan: This is a set of steps the Core Teams progressively go through when analyzing the Pilot Plant/ Area. It enables them to understand the equipment, measure the problems, analyze then fix the condition of the equipment and lastly pass on specific technical or support issues still to be resolved.
By doing so the teams will improve the equipment, but more importantly, they will discover the real reasons why the equipment is in the condition we see it and why it’s not performing in the way we would want. Some of these issues can be fixed quickly and some are more long term. Only the critical plant and equipment will be subject to the 9 Step Improvement Plan.
OEE (Overall Equipment Effectiveness): A measure used in TPM to calculate the percentage of the actual effectiveness of the equipment. Taking into consideration the availability of the equipment, the performance rate when running and the quality rate of the manufactured product measured over a period of time (days, weeks or months).
Operational Improvements: Improvement activities that result in increasing the equipment’s reliability once implemented by the TPM core team. The objective is to make it easy to do things right and difficult to do things
Pillar Champions: Initially there are five very important capabilities that everyone needs to embrace if TPM is to flourish. These are:
1. Continuous Improvement in OEE (OEE)
2. Maintenance Asset Care (MAC)
3. Operator Asset Care (OAC)
4. Skills Development (SD)
5. Early Equipment Management (EEM)
Asset Care Programme: A systematic approach to keeping equipment in ’as new’ condition. This consists of carrying out routine activities such as cleaning and inspection (carried out by the operator and sometimes called Operator Asset Care or Autonomous Maintenance), checking and monitoring (sometimes called Condition Based Monitoring), preventative maintenance and servicing (sometimes called Maintenance Asset Care).
P-M Analysis: A problem-solving tool used in TPM in conjunction with the five whys. The 4 Ps and the 4 Ms stand for:
4 Ps -phenomena that are physical in nature which cause problems that can be prevented.
4 Ms – are caused by machines, manpower, methods, and materials.
Performance Rate: The actual performance rate of a machine or process, expressed as a percentage of a planned performance rate.
Problem Prevention Cycle: The third and final stage in the Improvement Plan when the TPM Core Team concentrates on preventing problems from occurring in the future.
Roll-Out: This is where we start implementing the TPM techniques across the whole site. This is so that we can begin to get everyone involved and contributing to the TPM process. This also has a number of stages (called Phases). These are staggered so that we implement TPM at a sustainable rate.
Quality Loss: Lost production due to the manufactured product not being produced right the first time and which will, therefore, need to be either re-worked or scrapped.
Quality Rate: The first time ok product, expressed as a percentage of the total manufactured.
Reduced Speed Loss: Production lost due to running equipment at a speed slower than it’s intended or designed speed.
Set-Up and Adjustment Losses: Production time lost because a machine is being set up or adjusted at the start of a run.
Six Losses: These are the categories of losses the TPM teams use to identify and measure plant problems so that they can prioritize them and progressively reduce or eliminate them. These are the things that affect your Overall Equipment Effectiveness (OEE) score. The six Losses of the Production system are as following:
2. Excessive Set-Up and Changeover
(These two affect whether the machine is available to produce or not. This is why we use this as the AVAILABILITY percentage within the OEE calculation)
3. Idling and Minor Stops
4. Running at Reduced Speed
(These two affect the PERFORMANCE of a machine when running. This is the percentage rate within the OEE calculation.)
5. Reduced Yield (Scrap & Rework)
6. Start-Up Loss
video credit: CNC CAD CAM ACADEMY OF SIGMA YOUTH ENGINEERS