Creating a Life-Cycle Cleanroom Maintenance Plan
Maintenance is key to a cleanroom`s return on investment.
By Tony Waring
Afew years ago, the cheap price of my seat for the Heathrow to Washington flight was made possible [in part] because the aircraft required only two engines. I cross the Atlantic several times each year–in earlier days, on propeller-
driven aircraft. Having served on the technical staff of a Royal Air Force bomber group, I subscribe to the redundancy school, which holds: “Two engines good–four engines very much better.”
I settled in for my “maiden” twin-engined crossing and tried the overhead seat light. It didn`t work. When I reported this to one of the flight attendants, she leaned over and flicked the armrest switch a few times herself. “Oh dear! Our technicians seem to have missed that one,” she said. Disturbed, I asked: “But this aircraft only has two engines. What happens if they missed a fault with them?” With a smile spreading across her face and in an accent that would have made Scarlett O`Hara blush, she replied, “No sirree…you`ve surely got nothing to worry about there…I do believe the engines are on a different switch.”
The point is that in the wider context of corporate management and profitability, production is often the overriding imperative, and anything, including maintenance, that slows or stops it is an interference–a heavy overhead viewed only as a necessary evil. Instead, a cost-effective maintenance plan should be recognized as contributing to the long-term viability of the cleanroom and its continuing operations.
Strategy considerations
In general management circles, cleanroom operations are often surrounded by a certain mystique, despite the fact that clean conditions are used for an ever-widening range of activities, from super-advanced technologies to the very mundane.
The decision “To cleanroom…or not to cleanroom” is driven by one of two criteria: “Those processes which must be done under clean conditions,” whether for technical or regulatory reasons, or alternatively, “Those processes that benefit from their use.”
Whichever criterion applies, the capital investment to build and equip a cleanroom is considerably greater than for a conventional industrial environment, and running costs are also significantly higher. These factors highlight the importance of maintaining a facility at optimum performance readiness and delivering an acceptable return on the investment made in your cleanroom.
All cleanrooms are not equal. For example, at the most critical end of the scale are aseptically produced, sterile parenteral [injectable] drugs, the manufacturing processes of which must protect them from viable organisms and which are regulated [and inspected] for performance by government agencies and controlled worldwide by the observance of current Good Manufacturing Practices.
At the other end are microchips made in wafer fabs. In the overall scheme of things, the number of wafer fabs is minute compared to the tens of thousands of other cleanroom facilities. However, they enjoy a certain distinction in being extremely expensive to install, their control driven simply by financial considerations. They are financially sensitive to utilization levels, and the return on investment can only be realized fully if the fab operates at or near full capacity.
Despite the headline news items for new $1 billion fabs, it`s probably true that the majority of wafer fabs are relatively old “cash-cows” and depend on maintenance and development for their continued profitability. In between are the many and various cleanrooms handling such things as disk drives, medical devices, MEM fabrication, cleanroom clothing, LCD screens, medicines, fiber optics, plant breeding, biotechnology, blood fractionation, food production, orthopedic implants, injection molding, welding, etc.
The following maintenance plan is generic and based on discrete tasks defined as “maintaining”:
Cleanroom services and supplies
Cleanroom passive equipment and fittings
Existing production equipment
Cleanroom cleanliness
Installation of new and/or replacement production equipment.
The engineering requirements for all these tasks are almost certain to be intrinsically straightforward. However, apart from corporate profitability and the resources allocated to the task, cleanroom maintenance considerations are influenced by a range of additional factors–major subjects in their own right–and may include, but are not limited to:
The product and its sensitivity to contamination
Cleanroom design and engineering
Classification and size of the cleanroom
Complexity and density of fit-out
Cleanroom utilization and occupation levels
Process-generated contamination
Quality systems and validation procedures
Interdepartmental structure, relationships and flexibility
Personnel selection, management and training.
Maintenance philosophy
Maintenance philosophy falls between two extremes. At one end, nothing is left to chance and, regardless of performance, components are stripped down, inspected and/or replaced at clearly specified intervals. This applies to commercial airplanes, although the defining example is a Formula One racing team, which strips the car down to its basic components after each practice session and race.
The other extreme leans heavily on one maxim: “If it ain`t broke…don`t fix it.” That`s fine, but you must resolve whether or not optimum performance can be best achieved on the basis of maintenance by emergency repair and replacement or by using shutdowns to undertake pre-preemptive tasks.
Another example is the woodsman-and-the-ax parable. During the ax`s 20-year life, the woodsman fitted it with 10 new heads and 10 new shafts. Did the woodsman practice “remedial maintenance” and change a shaft when it broke, or did he adopt “pre-planned preventative maintenance,” where he planned ahead and replaced a shaft when its useful life had passed and it was liable to break? For him, maintenance was limited to two components. But in even the simplest cleanroom, performance depends on the continuing effectiveness of a variety of items, both active and passive.
The maintenance needs and time scales for a complex machine tool are self-evidently different from those of antistatic flooring or laminated work benches. However, in the cleanroom, such fixtures–which would normally enjoy very long lives outside–must be replaced when worn or damaged.
In fact, every energy-consuming item has an effectiveness curve. In addition, new installations suffer teething problems with a likelihood of early failures. But once commissioned and validated, the installation can be expected to work at optimum for a sustained period, and then with age, to suffer an accelerating loss of efficiency with decreasing mean times between failures.
To achieve an adequate return on investment, the cleanroom must be capable of continuous operation through life-cycle preventative maintenance.
Life-cycle preventative maintenance
Most people probably visualize a fully equipped operational cleanroom as having three dimensions–as a snapshot of something static. If you are responsible for its maintenance, that`s the wrong visualization because a cleanroom is dynamic, and it is far better to think of it as having four dimensions. Time is the fourth dimension, because you are expected to keep the facility at optimum performance over the life of all its component parts, over their complete working life-cycles.
In addition, the essence of preventative maintenance is: work should be done as a systematic pre-planned activity to provide assurance that the cleanroom will always be at readiness and its operational quality maintained. The key is for maintenance to be carried out regularly, effectively and with minimum disruption to production processes or other work of the plant.
“Life-cycle preventive maintenance,” therefore, calls for every item of equipment to be assessed individually to predict its life, the life of each component, and the service intervals necessary to ensure optimum performance during its total anticipated operational life.
Cleanrooms present an additional problem because the many acts of maintenance create contamination and can rarely be undertaken when the cleanroom is operational. In addition, the room must be returned to its clean state before work can resume.
In fact, maintenance is an ideal activity for a quality management system such as the ISO 9000 Standard, which requires a clearly defined written [maintenance] policy and provides the structure for systematic, documented working. With these proactive systems, all maintenance activities are the subject of standard operating procedures that detail how, when, and under what conditions work will be carried out. More to the point, every activity will be specified, documented, and verified on completion.
There is often resistance to the apparent rigidity and formality of quality standards, though this is sometimes voiced most heatedly by those whose knowledge is limited to gossip and anecdote, and who may have most to fear from the adoption of audited systematic work practices. In fact, most organizations employ some form of quality management system, although the adoption of a formal registered and third-party audited quality system is still very much in the minority. For the record, early in 1996, the worldwide total of ISO 9000 registered organizations approached about 100,000–some 40,000 of those in the United Kingdom–although the numbers everywhere are increasing rapidly, particularly in the United States, India and the Pacific Rim.
With government-regulated airplanes, engines are automatically replaced at a predetermined number of hours flown, and the aircraft itself is stripped down for examination and service at other predetermined periods. This approach can be applied to highly intensive cleanroom operations, for example, environmental and process filters, production tooling, or even light tubes, which some companies replace across the board at fixed intervals on the grounds that they have a predicted life-cycle and provide reduced illumination with age.
On the other hand, the policy may be to check items for efficiency at predetermined periods and to replace only on the basis of failure. Quite clearly, attitudes are affected by corporate culture, size and the financial climate. However, as with the busy sales and marketing department where the customer comes between them and their real work, the same syndrome can apply in a reactive maintenance department. Most commonly, the maintenance plan will be a hybrid of pre-planned replacement plus inspection, service and remedial replacement.
Rules of Engagement
With the best will in the world, the various functional managers in a company are subject to individual pressures that can lead to conflicting views, actions and reactions. The cleanroom may often represent only a small part of the total site installation and be dependent on inputs from several departments. It is likely that maintenance is controlled by the senior site maintenance manager, with others responsible for potentially conflicting functions such as product development, production, quality assurance, and engineering, while the actual running of the cleanroom is vested in another pair of hands.
A critical need of cleanroom maintenance is that all these disparate inputs be subject to flexible and equitable interdepartmental relations. There are many conflicts of interest out there, a fact bought home by the following example. An integrated production line had been installed in a plant for several months and was subject to daily operational and maintenance problems.
The line was fed bulk finished product, which it then packaged into single containers, labeled and weigh-checked them, and formed and filled each intermediate package, complete with instructions, before finally forming and packaging multiple units into shipping containers through the cleanroom wall. It emerged that the six major items of the automated plant had been purchased separately from six different manufacturers, with powered linking conveyors coming from a further vendor.
Among other communication weaknesses, Product Development had been responsible for system design and control, and although an individual had been appointed to supervise the project, more to the point, he had not been given a multi-departmental supervisory and communication remit. As an aside, it might have been better to appoint one of the vendors as the prime contractor responsible for the supply and commissioning of the whole project. Whichever project management approach was adopted, there should have been a clear command structure and rules of engagement.
The crux of the story is that routine maintenance had not even been considered when planning line sitting or service supply routes. The result was that access to service critical components was impossible. This may be an extreme case; nevertheless, it`s not unusual to hear several department managers claiming lack of prior consultation or joint working on a wide range of necessary interrelated subjects.
Effective maintenance begins at the planning stage, not after the project has been designed, ordered and installed. It is one of the clear-cut advantages of validation now spreading throughout the pharmaceutical, biotechnology and other cGMP-controlled industries. Its effect is that the input of all functional disciplines is formally interrelated at every stage. The other advantage is the emphasis placed on personnel selection, their management and training–a significant subject for examination where cleanroom maintenance is concerned. n
Tony Waring trained as a production engineer, but has spent many years involved with contamination control, cleanroom design and management, quality management and training, particularly in cGMP-regulated industries. These have included pharmaceuticals, medical device and biotechnology, as well as microelectronics, precision manufacturing and service industries. In 1989, he formed a consulting firm, Micron Management Ltd. In 1992, he founded and is chief executive of the Micron Video International companies. A fellow of the Society of Environmental Engineers, he chaired its Contamination Control Group for eight years, during which he was President of the ICCCS in 1991 and 1992. Waring was Chairman of the Standards and Practices Committee of the ICCCS when agreement was reached to begin work on the ISO/TC 209 International Standard for cleanrooms and associated controlled environments. He was a [founder] member of the organizing committee of the Parenteral Society for 10 years.
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Maintenance must deliver a proper return on the cleanroom investment. Photo courtesy of Micron Video International, Ltd.
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The cleanroom must always be returned to its operational state. Photo courtesy of Micron Video International, Ltd.
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Sterile cleanrooms are regulated by government agencies. Photo courtesy of Micron Video International, Ltd.
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Engineering is nearly always intrinsically straightforward. Photo courtesy of Micron Video International, Ltd.
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Routine maintenance starts at the design stage. Photo courtesy of Micron Video International, Ltd.