Many confuse availability with equipment reliability. In reality, it is only one part of the calculation. Availability is the actual time that the machine or system is capable of production as a percent of total planned production time. Availability rate should not be confused with overall availability. The latter is calculated using total calendar time as the divisor, not planned production time.
Most plants do not have a formal reliability engineering function nor do they have programs that directly address reliability problems. In a few instances, product quality and maintenance management programs acknowledge equipment reliability as an issue. However, these programs do not include specific programs that will improve reliability.
In part, this omission is created by our inability to assign responsibility for equipment reliability. Maintenance has an important role; but so do production, plant engineering, purchasing, sales and training. Each of these plant functions has a direct impact on performance.
Poor maintenance practices are perceived as the dominant factor that limits production capacity, product quality and profitability. In some cases, this perception is valid; but most of the reliability problems that adversely affect plant performance are not attributable to poor maintenance.
Many of the perceived maintenance problems are really outside of the maintenance function. Improper operating procedures, poor design or improper scheduling of production is the real sources of many plant reliability problems. These plant functions must also assume an active role in equipment reliability.
Asset dependability begins with the specification and selection process. The plant engineering and purchasing functions must actively pursue reliability as part of the process. Life cycle cost, maintainability and employee skill requirements must be key factors in the decision-making process. The purchase price of new and replacement systems are not a true measure of equipment cost or its impact on overall plant performance.
Purchasing must also use good judgment when selecting replacement components for both maintenance and production. Too many plants select vendors and components solely on costs. Little or no consideration is given to a component’s life cycle cost or its impact on reliability. As an example, one client elected to purchase a light-duty bearing for critical foundry exhaust fans.
The decision was based on a purchase price that was $5 less for each bearing. Because of this decision, the mean time between failure of these fans dropped from six years to six months. Purchasing must assume an active role in equipment reliability. Without their support and active participation, acceptable plant performance levels are not achievable.
Production has the greatest role to play. For every maintenance-related problem, there are 50 problems generated by poor operating procedures or methods. Operator error is an obvious cause of equipment downtime and product quality problems. However, production's contribution to poor performance is much greater. We have just concluded an evaluation of a 4-high tandem mill for one of our integrated steel mill clients.
Our task was to improve the overall performance of this complex production system. Eighty percent of the problems that restricted the system's capacity, product quality and costs were directly attributable to poor operating procedures and practices. Most of the problems were easy to correct and none required a financial investment.
Sales and marketing directly affect equipment reliability. The sales function determines how most plants operate. In some discrete manufacturing plants, this does not present a serious problem. However, in continuous process plants, such as steel and paper, poor sales strategy can have a serious, negative impact on plant performance.
If the sales function loads a plant with short-run, low-quantity orders, the number and frequency of machine setups will increase. This constant stopping, setup change and restart have a direct impact on reliability, product quality and capacity. Historically, a high percentage of product rejects and lost capacity can be attributed directly to setup changes. Rejects increase as the system stops.
Improper setup often creates a marked increase in rejects, as the line is restarted. Coupled with the time lost to the change of product, these short-run orders contribute significantly to poor plant performance. Higher levels of performance, including reliability, are not achievable when plant assets are not able to run without constant starts and stops.
Employee skills are also a critical part of equipment reliability. Operators and maintenance personnel must have adequate knowledge and proper procedures to follow before an acceptable level of performance is achievable. The training function must accept its role in supporting equipment reliability.
Without the training function’s support, acceptable skill levels will not be achieved. Inadequate standard procedures for both operation and maintenance also contribute to poor reliability. In most cases, standard operating and standard maintenance procedures do not provide enough data to properly operate or maintain plant equipment.
These shortcomings are too often viewed as employee failures. Management assumes that the workforce lacks the skills or motivation to perform their duties. In many cases, the failure is in the procedures and not the employees.
Who is responsible for asset reliability? The answer is both simple and complex. Everyone must take an active role. A viable reliability improvement program must start with corporate management.
They must establish and support policies that create an environment that is conducive to maximum utilization of manufacturing and process systems. Without their active support, improvement is difficult to achieve. Unfortunately, lack of corporate leadership and support is the norm, and often contributes to poor equipment reliability.
Plant engineering, purchasing, production, maintenance and training are the critical functions. Life cycle cost, ease of maintenance and reliability must become their primary focus. They must work together with a common objective – to achieve the best performance from all plant equipment and systems. If you can improve the reliability of your equipment, product quality, increased capacity and profitability will follow.
Integration of Plant Functions
Regardless of the product or production type, all plants are integrated. Each of the functional groups, such as purchasing, maintenance or production, depends on other functions. Without an integrated, coordinated effort by all functional groups, reasonable levels of performance are not achievable. The premise of a viable continuous improvement program must be that maximum plant performance depends on the integration of all critical functions within a plant.
Plant engineering, purchasing and other plant functions have a direct impact on equipment reliability, availability, and total operating costs as does maintenance and production. Each of the critical functions must work in conjunction with both production and maintenance before measurable plant improvement is achievable.
Optimum performance of critical plant production systems also depends on the integrated efforts of these critical plant functions. Many of the factors that adversely affect product quality, production capacity and total operating costs are directly attributable to failures in the design, purchasing or installation of critical manufacturing systems.
To achieve sustainable performance one must will establish design, purchase and installation criteria that will assure optimum performance levels from all plant systems over their full useful life. The methodology, based on life cycle costs, will provide standard procedures and equipment evaluation methods that will eliminate limiting factors before they enter the plant.
Sales and Marketing
The sales and marketing group must provide a volume of new business that can sustain acceptable production performance levels. Asset utilization requires a backlog that permits full use of the manufacturing, production or process systems. However, volume is not the only criteria that must be satisfied by the sales and marketing group.
They must also provide a product mix that permits effective use of the production process; order size that limits the number and frequency of setups; delivery schedules that permit effective scheduling of the process; and a sales price that provides a reasonable profit. The final requirement of the sales group is an accurate production forecast that will permit long-range production and maintenance planning.
Production
Production management is the third criteria for acceptable plant performance. The production department must plan and schedule the production process to gain maximum use of their processes. Proper planning depends on a number of factors: good communication with the sales and marketing group; knowledge of unit production capabilities; adequate material control; and good equipment reliability.
Production planning and effective use of production resources also depends on coordination with procurement, human resources and maintenance functions within the plant. Unless these functions provide direct, coordinated support, the production planning function cannot achieve acceptable levels of performance from the plant.
In addition, the production department must execute the production plan effectively. Good operating procedures and practices are essential. Every manufacturing and production function must have and use, standard operating procedures that support effective use of the production systems. To ensure proper use of critical plant assets, these procedures must be regularly evaluated and upgraded.
Read more on overall equipment effectiveness.
Procurement
The procurement function must provide raw materials, production spares and other consumables at the proper times to support effective production. In addition, these commodities must be of suitable quality and functionality to permit effective use of the process systems and finished product quality.
The procurement function must coordinate its activities with both the maintenance and production functions and implement and maintain standard procedures and practices that ensure optimum support. At a minimum, these procedures should include vendor qualification, procurement specifications based on life cycle costs, incoming inspection, inventory control and material control.
Maintenance
The maintenance function must ensure that all production and manufacturing equipment is in optimum operating condition. The normal practice of quick response to failures must be replaced with maintenance practices that will sustain optimum operating condition of all plant systems. It is not enough to have production systems operate.
The equipment must reliably operate at or above nameplate capacity without creating abnormal levels of product quality problems, preventive maintenance downtime or delays. The objective should be maintenance prevention, not quick fixes of breakdowns.
Maintenance planning and scheduling is an essential part of effective maintenance. Planners must develop and implement both preventive and corrective maintenance tasks that achieve maximum use of maintenance resources and the production capacity of plant systems. Good planning is not an option. Plants should adequately plan all maintenance activities, not just those performed during maintenance outages.
Standard procedures and practices are essential for effective use of maintenance resources. The practices should ensure proper interval of inspection, adjustment or repair. In addition, these should ensure that each task is completed properly. SMPs should be written so that any qualified craftsperson can successfully complete the task in the minimum required time and at minimum costs.
Adherence to SOPs is also essential. The workforce must have the training and skills required to complete their assigned duties. In addition, maintenance management must ensure that all maintenance employees follow standard practices and fully support continuous improvement.
Conclusions
Statistical analyses conducted by a number of industrial, trade and professional organizations conclusively point to the fact that maintenance is the primary source of less than 20 percent of availability losses. The majority, as much as 85 percent, is the result of deficiencies in other functional groups or functions within the plant or corporation.
Therefore, the solution to availability problems should be clear – a holistic approach to standardized, value-added business and work practices that assure availability, best quality and lowest total cost of ownership. Single-focused approaches, such as maintenance improvements, simply will not generate enough benefits to warrant the effort – it cannot affect the majority of the factors that limit availability.
About the author:
Keith Mobley is a principal consultant with Life Cycle Engineering. Keith has earned an international reputation as one of the premier consultants in the fields of plant performance optimization, reliability engineering, predictive maintenance and effective management. He has more than 35 years of direct experience in corporate management, process design and troubleshooting. For the past 16 years, he has helped hundreds of clients worldwide achieve and sustain world-class performance. He is actively involved in numerous professional organizations. Currently, he is a member of the technical advisory boards of the American National Standards Institute (ANSI), the International Standards Organization (ISO), the American Society of Mechanical Engineers (ASME) and others. He is also a Distinguished Lecturer for ASME International. For more information, e-mail kmobley@LCE.com or visit www.LCE.com.
About the Author
R. Keith Mobley has earned an international reputation as a leader in corporat... Read More