In the ever more competitive marketplace, manufacturing companies are under relentless pressure to increase profit margins, improve market shares and expand product portfolios while ensuring low-cost production, enabling a highly agile supply chain and serving a global market. These aren’t trivial challenges, and every company deals with them in unique ways. Companies constantly look for best practices and new management philosophies that can help meet these challenges and leapfrog the competition.
During the past decade, lean concepts, cellular manufacturing and quality circles have been on the forefront of management philosophies and practices that have helped companies face these challenges. In addition to these well-known concepts, there also is a practical concept, relatively undersold in the Western world, that has been practiced for a long time by many Japanese and Asian companies. It offers a sure-shot method to achieve overall lifetime manufacturing cost reduction with increased efficiencies in quality and reliability. It’s called total productive maintenance (TPM).
TPM combines the age-old American principle of preventive maintenance with Japanese concepts of total quality management (TQM) and total employee involvement to revolutionize how manufacturing facilities address machine and office maintenance. It’s built on the principles of empowering people at every level, fostering a sense of community ownership in operations as well as extending the reach of TQM, 5S (a Japanese system of organizing the workplace) and visual factory concepts.
TPM’s goal is to achieve zero breakdowns, zero accidents and zero errors. It fundamentally shifts the maintenance responsibility from maintenance departments to shop-floor production departments. While traditional maintenance programs have centered on machine maintenance, TPM encompasses the entire gamut of operations in the plant, including those of administrative departments and support departments, to achieve system-wide effectiveness.
How it works
TPM defines eight broad areas, called the pillars, each focusing on achieving the zero breakdowns, zero accidents and zero errors:
- Autonomous maintenance (jishu hozen)
- Continuous improvement (kaizen)
- Planned maintenance
- Early equipment management
- Quality maintenance
- Office TPM
- Safety, health and environment
Each pillar focuses on a specific set of activities and tasks. For the purposes of this article, I’ll zero in on autonomous maintenance and planned maintenance. Both concepts can be implemented and sustained with relatively low cost and, at the same time, give a marked increase in productivity through reduced downtime.
Also called jishu hozen, autonomous maintenance involves a seven-step process for achieving operator-controlled maintenance. This empowers operators (who usually have the most knowledge of their equipment) to perform day-to-day maintenance activities. This reduces shop-floor dependence on the maintenance department to perform routine maintenance activities. It produces a win-win situation for both the operators and the maintenance technicians. The operators take pride in ownership of their equipment, with which they are intimately familiar. The maintenance department can concentrate on planned maintenance programs.
The seven steps in the autonomous maintenance pillar are:
- Initial cleaning
- Eliminate maintenance hurdles
- Develop provisional standards
- General inspection
- Autonomous inspection
- Autonomous management
Before any of these steps are started on the shop floor, operators, supervisors, and production and maintenance managers should be educated on the concepts of TPM and given the reasons why the plant is undertaking this program, as well as complete management involvement and support for these activities.
Initial cleaning: Although this is basic and in some ways, just common sense, it’s often overlooked in day-to-day operations when no time is invested in the initial cleaning activity. In this process, specific machines are targeted and a date established for performing this activity. On that date, shop floor employees begin a comprehensive cleaning of the targeted machine with assistance from the maintenance department. They remove dust, stains, grease and oil from around the machine. A comprehensive color-coded tagging process identifies loose and leaky parts, worn out components, unsafe equipment shields, faulty hydraulic and pneumatic lines, etc.
The colors indicate which tasks can be performed by the equipment operator, and which need the assistance of maintenance personnel. Inaccessible areas of the machine that are critical to its functioning get tagged for corrective action to make these areas more accessible to operators. After tagging has been completed, perform the indicated corrective work. After the initial issues have been fixed, run the machine on a trial basis to ensure that the problems have been resolved. Some companies paint their machines white after the initial cleaning has been completed so that any new oil leaks, stains and dust become more visible to the operator and quick remedial measures can be taken.
Eliminate maintenance hurdles: This step is essential to sustain autonomous maintenance among operators. Make any inaccessible machine region that is important to the maintenance process more accessible, thereby ensuring that operators can perform their maintenance tasks in a safe and painless manner. Access to points of lubrication and fuses, easy-to-remove shields for cleaning, providing scrap metal collector bins all assist in making machines much more maintenance-friendly for the operators.
Develop provisional standards: This step formalizes autonomous maintenance. It establishes a maintenance schedule and the inspection and lubrication standards. The provisional standards use the knowledge gained during the steps above to define a clear overall standard on how the machinery is to be maintained along with detailed documentation on the autonomous maintenance procedures the operators are to follow. These standards need to be updated whenever you add to or modify the machine. Operators and the production department own these standards and they share them with the maintenance department when they need expert maintenance advice.
General inspection: In this step, the cell leaders and plant floor supervisors will train the operators in the finer aspects of maintaining the machinery for which they are responsible and explain its functions within an inter-related set of systems. This includes training in the machine’s electrical, mechanical, pneumatic, hydraulic, lubrication and computer-related systems.
After the operators become familiar with the finer aspects, begin a cross-training program among other operators so that knowledge is shared and there’s a general consistency of knowledge in the operator group. Operators take great pride in gaining this type of knowledge, and in turn, it helps them grow in their career and gives experience in training new operators.
Autonomous inspection: The operators are now ready to perform autonomous maintenance on their equipment. In this step, operators and supervisors develop a detailed autonomous maintenance schedule. Using the previous standards, operators perform their own self-directed machine inspections and maintenance.
The provisional standards that drive this step are modified and refined based on machine improvements, which results in certain parts needing less inspection. Over time, the maintenance schedules also are fine tuned to achieve optimum balance between scheduled equipment upkeep and daily 5S activities around the machines.
Standardization: While the steps above are machine-focused, standardization addresses the paraphernalia that are essential for machinery upkeep. This represents an extension of the 5S process, where the tools and essential spare parts are organized, stored and tracked in a systematic manner. Job aids, standard operating procedures and work instructions are kept in the custody of the operators for ready reference.
Autonomous maintenance management: At this stage, the operators have the tools, techniques and knowledge required to sustain the autonomous maintenance program. The operators become involved in kaizen (continuous improvement) initiatives, plan-do-check-act (PCDA) cycles, cell audits and quality circle initiatives with a singular focus on breakdown prevention and safe equipment operation.
Unlike autonomous maintenance, which is operator-led, the maintenance department spearheads planned maintenance programs. Planned maintenance program tasks involve specialized skills and are at a much higher technical level in terms of complexity and comprehension. An effective planned maintenance program depends on having an effective autonomous maintenance program in place. The goal of a planned maintenance program is to ensure zero breakdowns and achieve optimal overall equipment effectiveness (OEE). Because the operational effectiveness of a machine correlates to its upkeep, planned maintenance programs concentrate on eliminating minor defects, preventing defects and adhering to strict maintenance schedules.
When following a planned maintenance schedule, however, there will be times where the machines require downtime for maintenance. This goes against the intuitive philosophy of always keeping the machines running at any cost. Little do people recognize that having planned downtime for maintenance is actually beneficial in the bigger picture of overall equipment effectiveness.
Performing scheduled maintenance activities is essential, because the maintenance technicians know which machines parts require attention. Therefore, the time and costs for planned maintenance are much less than for unplanned downtimes, when the machine could crash at a critical juncture in a manufacturing cycle. Planned maintenance also involves a change in culture among manufacturing managers, who often lose sight of a simple fact. Diagnosing and fixing machine failures as a result of a machine breakdown is more expensive and certainly won’t prevent similar future failure modes. Planned maintenance follows a six-step process:
- Evaluate equipment
- Restore deterioration
- Correct design weakness
- Build periodic maintenance system
- Build predictive maintenance system
- Establish planned maintenance program
The first two steps focus primarily on reducing process variability and removing known equipment defects, thereby restoring the equipment to a baseline condition. These steps are performed in conjunction with the initial cleaning phase in the autonomous maintenance routine.
The primary objective of correcting design weaknesses by eliminating root causes of contamination and failures is to lengthen the equipment’s lifespan. During this stage, simplify the maintenance and inspection tasks so that operators can perform their autonomous maintenance in a standardized manner.
Completing these steps should result in a dependable equipment condition so preventive maintenance can be planned and implemented. Time-based and cycle-based counters can feed information into a computerized maintenance management system to trigger preventive maintenance work orders. This step also helps to manage and control spare parts inventory, resulting in lower inventory carrying costs. At this stage, maintenance becomes focused on being preventive, rather than reactive.
Steps 1 through 4 give maintenance personnel valuable knowledge and deeper insight into the equipment’s functioning. Using information from diagnostic tools and by analyzing information from maintenance information systems, maintenance personnel can now scientifically predict failures. This enables them to develop predictive maintenance plans.
Although, in theory, achieving this stage is a logical extension from the preceding steps, the reality of getting here across the manufacturing operation is sometimes impractical and costly. Therefore, focus your efforts to get to this stage for critical operational equipment, which are considered bottleneck machines, and are vital in keeping the manufacturing plant running.
After you carry out steps 1 through 5, your planned maintenance program can reach steady-state operation. It will concentrate on continuously improving overall equipment effectiveness and bringing under the umbrella other areas of TPM, such as early equipment maintenance, quality maintenance and office TPM. It will exhibit a relentless focus on minimizing the six big losses (breakdowns, setup and adjustments, small stops, reduced speed, startup rejects and production rejects).
When manufacturers face extreme marketplace competition, TPM becomes a practical and result-focused program that can deliver consistently high-quality products at lower costs. Implementing and sustaining TPM programs is achievable only under the following conditions:
- Unwavering support from top management
- Total employee involvement at every level
- Relentless elimination of losses and pursuit of continuous improvement
- Making TPM a part of the organization’s culture
Typical of the results manufacturers that implement TPM programs have seen include a 40% to 50% reduction in machine repairs, 40% increase in planned maintenance activities, 15% to 25% increase in OEE, 40% to 50% increase in kaizen activities and a great sense of all-round employee involvement. Once TPM is implemented, it doesn’t become an end-state goal, but rather continues as a culture that is built upon to achieve manufacturing excellence.
Nat Parameswaran is director of the Business Solutions Group at United States Gypsum Co. in Chicago. Contact him at [email protected] and (312) 436-6457.