Total Productive MaintenanceIntroductionModern manufacturing practices hinge on the ability of machines and plant equipment to function with minimum downtime. The longer an equipment or a piece of machinery is out of operation, the larger is the incurred cost-without-return. While the American industries were slow to realise and wake up to this fact, the Japanese had developed concepts of continual improvement and adoption of best practices in the implementation of the plant efficiency. This has led to the Japanese companies emerge as the world leader in manufacturing sector, thus, dethroning American and several other “western” companies as the role-model and poster-boy of manufacturing industries.The tools and practices such as 5S, 6 Sigma etc., developed by the Japanese manufacturing giants have captured the attention of the manufacturing world across the globe.
One such practice for the efficient utilisation of plant infrastructure is Total Productive Maintenance.TPM is a productivity improvement practice, involving all the active members of a manufacturing organisation ( grass root to the top management level ), focussed on reduction of unproductive or idle time and processes which do not add any value to the transformation process ( raw material to finished goods ) by ensuring that the plant equipment is maintained at the highest possible level of working order, thus, cutting down on the unscheduled maintenance time in the event of break-down of machinery.TPM lays emphasis on the maximisation of the effectiveness of plant equipment by enforcing maintenance system for the entirety of equipment life cycle. Objectives of TPMThe manufacturing firms hope to achieve following, among many other, objectives thorugh the adoption of TPM practices:· Waste reduction in a dynamic economic environment· Maintenance of standard product quality during the production process· Reduction in production cost· Reduction in the production time for a batch of products· Defect-free production Understanding MaintenanceIndustries follow varies maintenance practices. · Corrective maintenance:This is done after the reports of a machine breakdown or imperfect performance is reported to the maintenance division. It is a reactive approach.· Preventive Maintenance: Proactive in the approach, this process involves constant checking and maintenance of points of criticality and vulnerability in a machine.
· Predictive Maintenance: Yet another form of proactive maintenance practice, predictive maintenance relies heavily on the data collected via sensors to predict an imminent failure, thus, leading to the preventive and precautionary measures being taken to avoid such an event.· Zero Hours Maintenance: This type of maintenance is carried out when the reliability of a machine plunges down drastically. It involves replacing the critical parts and restoring the machine to near new condition. “Overhauling” is the most common term used for such maintenance.· Periodic maintenance: This maintenance practice involves scheduled checks of the equipment at a set interval of time or production milestone irrespective of the performance of the machine at the given time.Total Productive Maintenance TargetsAdoption of TPM practices involves striving for following targets:· PAchieving 80% Overall Plant Efficiency (minimum).Achieving 90% Overall Equipment Effectiveness (minimum).
Zero idle time for machines during breaks during the working hours. · QAchieving zero customer complaints· CAchieving 30% reduction in production costs· D100% conformity to the requirements of the customers in terms of specifications and delivery· SMaintenance of an accident free working environment· MDeveloping multi-skilled and flexible workforceTPM MetricsMean Time Before Failure (MTBF)Total Running Time / Number of FailureMean Time To Repair (MTTR)Average time taken to address a breakdownAvailability of Machines (A)Time for which a machine is actually available/Time for which a machine should be availableA = (MTBF – MTTR) / MTTR Rate Efficiency (RE)RE = Actual Average Cycle Time / Design Cycle TimeSpeed Efficiency (SE)SE = Actual Cycle Time / Design Cycle Time Performance Efficiency (PE)PE = Rate Efficiency x Speed EfficiencyQuality Rate (Q) Number of Good Parts Produced / Total Number of Parts Produced x 100Overall Equipment Efficiency (OEE)OEE = A x PE x Q Pillars of TPM 5 SProblems inherent in an organization can be seen better when it is well organized. % S aims to achieve just that and drastically improve the visibility of problems.
Seiri : It involves sorting and organizing on the basis of their criticality, importance and frequency of use.Seiton: This involves designating a particular unique place for each item along with name tags for easy access and identification. Seiso: This process takes care of cleaning the place.Seiketsu: This deals with the standardization.Shitsuke: This final step takes care of implementation of 5S as a lifestyle, thus, ensuring that practices are followed in the future flawlessly. Jishu HozenThis involves enabling the operators so that they can take care of minor maintenance work themselves, thus, decreasing the workload and dependency on the dedicated maintenance teams.Targets: Prevention of the occurrence of 1A / 1B because of JH. Reduction in oil consumption by 50% Reduction process time by 50%Steps: Preparation of employees.
Clean-up of machines. Taking counter measures Fixing tentative JH standards Autonomous inspection Standardization Autonomous management. KaizenKaizen involves adoption of small but continuous changes instead of a big overhaul to achieve the overall quality target. This is aimed at reduction of losses mad wastage due to inefficient and improper practices. Target· 30% reduction in production cost · Zero loss in all the spheres of activity· Improving OEE· Focussing on easy handling of operatorsTools like PM analysis, 5Ws analysis, Kaizen register etc. are used. Planned MaintenanceIt is aimed to have trouble free machines and equipment producing defect free products for total customer satisfaction.
Policy : Achieving and sustaining availability of machines Optimum cost of maintenance. Reduction in spares inventory. Improving reliability and maintainability of machines.
Target : Zero equipment failure and break down. 50 % improvement in reliability and maintainability. 20 % reduction in maintenance cost Availability of spares all the time.
Six Steps in Planned Maintenance : Equipment evaluation and recoding present status. Restore deterioration and improve weakness. Building up information management system.
Prepare time-based information system, select equipment, parts and members and map out plan. Prepare predictive maintenance system by introducing equipment diagnostic techniques and Evaluation of planned maintenance.Quality MaintenanceThis pillar takes care of the customer end of the bargain by ensuring that the problems associated with non-conformity to specifications are eliminated systematically. The driving theory for this pillar is “A perfect machine produces perfect product”. Thus, it aims at eliminating defects by rectifying errors, if any, in the plant machinery. Quality maintenance takes care of both in-house as well as customer end defects.Policy : Defect free conditions and control of equipment Quality assurance though QM activities Prevention of defects at source Focus on poka-yoke In-line detection and segregation of defects.Target : Achieving and sustaining zero customer complaints 50 % reduction in in-process defects 50 % reduction in quality costTrainingTraining the employees and operators to be multi-skilled is one of the corner stones of TPM.
Training the operators and empowering them to take care of minor faults in the machinery reduces idle time of the machines, hence, leading to reduced cost of production. Operators should not only be given the “Know-how”, but also should be equipped with “Know-why”. A workforce of experts is the primary aim of this pillar of TPM.Policy : Focussing on improving the knowledge, skills and techniques. Creation of an environment for self-learning. Training curriculum / tools /assessment etc conductive to employee revitalization Training to remove employee fatigue.Target : Achieving and sustaining zero downtime due to want of experts on critical machines. Achieving and sustaining zero losses due to lack of knowledge / skills / techniques 100 % participation in suggestion scheme.
Office TPMOnce Jishu Hozen, Kaizen, Planned Maintenance and Quality Maintenance have been deployed, one can look forward to implementation of Office TPM to boost productivity, identification and rectification of administrative losses and increase administrative productivity. Following losses can be addressed by Office TPM : Processing loss Cost loss in areas such as procurement, accounts, marketing, sales, high inventories Communication loss Idle loss Set-up loss Accuracy loss Office equipment breakdown Time spent on retrieval of information Loss due to logistic incompetency Expenses on emergency dispatches/purchasesKobetsu Kaizen Topics for Office TPM : Reduction in inventory level Reduction in lead time of critical processes Retrieval time reduction. Equalizing the work load Increased office efficiency by elimination of the time loss on retrieval of informationSafety, Health and EnvironmentA safe workplace ensures minimal loss due to accidents. This reduces the cost incurred in addressing damages due to mishaps.
Target : Zero accidents Zero health damage Zero fires.ConclusionTPM, as a productivity enhancing tool provides many a benefits, both direct and indirect. Increased productivity ( 50 – 100 %), Reduction in manufacturing cost, customer satisfaction, improved complaint redressal, high confidence and positive employee attitude, knowledge sharing environment etc. are some of the most well known benefits of TPM.
Now, with a cut-throat competition in the industry, these benefits put a company in the driver’s seat and provide them a definitive competitive edge over their competitors. Thus, if applied properly, TPM is a very potent weapon which can be adapted to myriad industries with similar results. References: · F.L. Cooke, ‘Implementing TPM in plant maintenance: some organizational barriers,’ International Journal of Quality & Reliability Management, Vol 17 No.
9, 2000, pp 1003–1016.· A. Ginder , C.J. Robsinson, Implementing Total Productive Maintenance, Productivity Press, 1995· S. Nakajima, 1988, Introduction to Total Productive Maintenance, Productivity press, Cambridge, MA·