Most discussions in the media and across the conference circuit refer to the maintenance department as a single cog in the Lean machine. According to experts, however, the maintenance department is at the heart of any continuous improvement drive.

Lean manufacturing comes from the systems and processes of the Toyota Production System. Toyota has been heralded by industry-watchers as supremely effective at producing high-quality products while reducing costs and shortening cycle times. For more than 10 years, cult-like followers of the Lean movement across North American industry have dabbled in this innovative Eastern approach to cost-saving manufacturing.

Vought Aircraft Industries is just one aerospace manufacturer that has tried to go Lean.

Joe Bechtol, director of facilities and security at Vought says that its maintenance and engineering department was instrumental in the initial implementation phase and continues to play a key role in supporting the entire process. With both a traditional maintenance organization and a comprehensive engineering staff that incorporates electrical, mechanical and civil disciplines, Vought's maintenance crew handles two different yet related aspects.

"The engineering group lays out the process of change — redesigning the floor layout and cell operation — and the maintenance group implements the changes — moving, retrofitting and rebuilding equipment. When the floor comes up with a concept of change, we are instrumental in the implementation," says Bechtol.

Headquartered in Dallas, Texas, Vought Aircraft Industries, Inc. is one of the world's largest independent suppliers of aerospace structures. As a major provider of components for prime manufacturers of aircraft, the company has worked on virtually every Boeing jetliner in production, from the 737 to the 777. This 5,000 employee, $1 billion a year firm is roughly eight years into its Lean journey and openly discusses how its implementation has specifically impacted its maintenance and facilities engineering department.

Starting the journey
According to Vought's manager of engineering and lean implementation, Lee Mitchell, "Vought Aircraft started on its Lean journey in 1993 as part of the Lean aircraft initiative put together by the United States Air Force, Massachusetts Institute of Technology, and a handful of key aerospace firms. Collaboratively, as an industry, we realized that we needed to make some significant changes from the mass production methods we implemented."

The group looked at how the major U.S. automakers were competing with foreign manufacturers by implementing the Toyota production system. Vought started the process by studying as many texts as possible with the intent of trying to take the ideas and see how they could apply to the aerospace industry. For instance, Mitchell says they started by studying the popular book, The Machine That Changed the World by James P. Womack, Daniel T. Jones, and Daniel Roos.

As the Vought maintenance team learned more about implementation, they recognized that the Lean principles needed to go across the entire enterprise, so according to Mitchell, Vought started to involve the above the floor processes of business management, engineering, and other support organizations. In each of these areas they started to look at where they could improve their value streams and eliminate waste.

The next step was implementing a cross-company campaign that raised awareness of the Lean philosophy and reducing wasteful practices. Vought employees understand Lean principles and are aware of what management is trying to accomplish. "Employees now see what can be done individually and as team members to further the initiative by making improvements and eliminating waste," said Mitchell.

Obstacles and benefits
Undoubtedly, the biggest challenge any maintenance department involved in the process is the balancing of resources to meet the demanding needs of a Lean environment. Over time, the requests on maintenance actually increase and the load can be significant.

"Lean has taken a great toll on the assets of maintenance." says Bechtol. Obviously there are a limited number of man-hours and various budget constraints that any organization has to deal with. "Unfortunately, we have let some of the backlogged normal maintenance slide be-cause we've had to focus energies on im-plementing Lean. Costs are actually taken away from the general maintenance and applied in priority towards Lean," he says.

Despite this, it is crucial to remember what Lean implementation is doing for the organization in the big picture, Bechtol says. "Understanding that makes a maintenance group set some priorities to meet the goals. You need to adjust to improve the production stream, which will eventually improve your cost structures. It does, however, definitely impact the day-to-day."

Some of the ways Vought has been able to cut waste has been in travel. By limiting the movement of both people and equipment Vought has been able to reduce its travel budget by 50 percent. Some of the perishable materials have been streamlined and reduced in need. And the maintenance department has been able to find items that are obsolete, thereby taking items offline and reducing the spare parts inventory, further helping with the cost structure. "Being able to eliminate outdated equipment has helped with the budget constraints," says Bechtol.

According to Mitchell, company-wide the most noticeable benefits have been in reduced inventory and span times through waste elimination. Response time has been improved, and taking Lean principles into consideration throughout the production process has yielded a positive impact upon the quality of the product. "The Lean tools are ensuring first-time quality allowing the firm to realize the next step of gains," said Mitchell.

Words of wisdom
Having eight years experience in the never-ending conquest of Lean implementation provides Mitchell and Bechtol with the opportunity to share some valuable advice to those that are new to the Lean process.

First, communication is absolutely essential. Not just at the management level, but to the individual on the floor. Everyone must have an understanding of the process to be a success. In union shops, bring labour on board early. This is key to demonstrating that the point of Lean is not to eliminate jobs but to eliminate waste.

Secondly, there must be support of the senior staff. "Support of the senior staff shows the employees that it is not just some trendy management flavor of the month. There must be a commitment. The CEO should be out on the shop floor showing the company's commitment to the initiative," said Bechtol.

Third, there must be a commitment of resources. There must be a budget of funds within the organization dedicated to the Lean initiative. If there is not a true commitment of resources, you will find that you are spreading out your Lean funds too thin. Involving the Lean implementation team in this process is key since this gives implementers an idea of whether or not an activity is cost-effective in the long run. Cooperation between implementation and maintenance groups is critical.

Fourth, stick with it. Anyone at all familiar with Lean will echo that it is not a short-term process. It is a continual operation and it takes years to realize the many benefits.

"You must have patience before you will see the benefits," says Mitchell. Realization in inventory reductions will definitely take time, especially if you are part of a firm that is historically sitting on a large amount of inventory."

Unlike the many utopian production models that have come and gone over the years, the concept of Lean manufacturing is actually an enterprise-wide approach to integrating efficiency.

Patterned after the popular and highly effective Toyota production system, Lean essentially incorporates proven methods aimed at removing any form of waste from daily manufacturing processes, regardless of department, without necessarily adding any new equipment.

What role should maintenance take in the planning and implementation processes? How should a maintenance manager go about integrating the Lean principles into the department operations? In what aspects does Lean truly impact the maintenance department?

Role in planning
Implementing Lean within any enterprise necessitates the ability of various departments to work in conjunction with one another as a team with a congruent mission or goal. Typically, the initial team planning and brainstorming meetings are referred to as Kaizens. Initially, maintenance will play a key role in Kaizens as the enterprise is restructuring its production environment to eventually meet the overall goal of single-piece flow capability.

According to Sam Swoyer, Vice President of TBM Consulting Group (www.tbmcg.com), a consulting firm based in Durham, North Carolina that helps firms transform their operations into Lean enterprises, "Maintenance is an especially important cog in the beginning of the Lean implementation process.

Using the Kaizens breakthrough process, we create diverse teams that develop methods to capitalize on continuously improve." says Swoyer. "And initially, we work almost exclusively to develop smooth workflow, which in many cases results in the need for the quick movement of equipment to suit the desired need."

One of the key areas of activity for a maintenance department is the ability to support this type of event. Recognizing that the traditional maintenance approach is to take a series of CAD drawings, study the move, brief everyone on the project and make the necessary moves during a plant shutdown, the prompt moves implemented during a Lean reorganization can be quite taxing. So, initially the maintenance organization must be very flexible and be able to prepare for a number of different situations.

Effectively eliminating waste
This is always one of the most difficult aspects of implementing Lean — recognizing how your existing methods fail. In order to recognize waste within the department it may be necessary to rely somewhat on criticism from external departments. Since individuals within these departments are not intimately involved in your affairs they have less of an attachment — much like an editor reviewing a writer's work. One of the best ways to handle this is to implement a cross-categorical Kaizen blitz to recognize potential areas of improvement.

Once the production workflow is improved it is crucial for the maintenance department to use the same Kaizens to find areas within the maintenance department that need improvement and to develop solutions. Once aware of the areas that demand immediate attention, it is time to draw up a plan of attack.

As Bill Fetterman president of consulting and Lean implementation firm CMD says: "It is crucial for a firm serious about Lean to implement a system for ensuring that maintenance plans and systems meet the needs of the operating teams, thereby guaranteeing that equipment effectiveness is understood, measured and improving; equipment uptime meets the needs of the manufacturing operating teams and systems are in place to monitor equipment performance; and that maintenance activities are reviewed for sufficiency. Undoubtedly, the goal is 100 percent predictability of equipment performance. Remember however that having smaller inventories yields limited tolerance for unscheduled downtime."

Long-term effects
As one would expect, the implementation of such an all-encompassing program will have long-term effects to each department involved. Routinely for the maintenance department, it will entirely restructure the duties of the staff.

Traditionally maintenance departments have been reactive rather than proactive and when fully implemented, the Lean maintenance department will be a predictive group using tables and tools designed to ascertain that costly downtime will not occur. Undoubtedly, downtime does occur, but through the implementation of various Lean principles, maintenance is able to label equipment and provide production employees with the training necessary to understand how a machine is operating which can significantly enhance a maintenance department's ability to attack a situation before it becomes a problem through proactive operator interaction. Specifically, the training allows an operator to better detect abnormalities that when unnoticed and left untreated can lead to significant downtime.

Grand Rapids, Michigan-based Cascade Engineering is an ideal example since it has been very successful in using Lean to train its operators to assist the maintenance department. As a portion of the training, the maintenance department has effectively labelled all areas of concern on its machinery. The labelling of all aspects of the equipment facilitates easy maintenance and identification. For example, when the rear hydraulic assembly is leaking, the operator can call maintenance and let them know exactly where they noticed a problem thereby eliminating guesswork and yielding shorter downtimes. Furthermore, systematic checks are identified on the machine in red or yellow lettering identifying the necessary order. For instance, weekly check step one would be written inside a box with red lettering.

Over time maintenance's role can take a drastic turn. According to TMP, "After the initial moves are made and workflow is optimized as far as machinery moves are concern, maintenance gets actively involved in improving fixturing, rebuilding and upgrading tooling, modifying equipment to capitalize on automated processes." In many cases the maintenance department actually must become much more creative in its role.

Such resulting creativity is quite evident in many of Grand Rapids, Michigan-based automotive components producer, Lacks Enterprises. Lacks starting integrating Lean concepts a few years back and has already seen drastic changes within the role of its maintenance departments. Robert Tice, Maintenance Manager at the Barden St. Assembly plant has taken the opportunities provided by Lean to begin implementing more automation solutions. For instance, at this facility, the maintenance department has designed and built a system that uses pneumatics to aid operators in lifting various wheel components thereby facilitating assembly by reducing the amount of time it takes to move components and further reducing the possibility of injury.

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Peter Fretty is a freelance writer based in Michigan. He can be reached at This e-mail address is being protected from spambots. You need JavaScript enabled to view it

Major cost items come in three flavours — capital investments, catastrophic failures and deliberate plant shutdowns. The first is subject to intense scrutiny/justification and, with the exception of the patchy adoption of life cycle costing, is pretty much understood. We are trying desperately to avoid the catastrophic events — and have been grappling with systematic and quantitative analysis methods for many years (HAZOP, QRA techniques, risk-based inspection etc.). The third area, planned shutdowns, is still an enigma for many organizations.

Much effort has gone into the efficient planning and delivery of the work involved, but relatively little guidance exists for determining what work is worth doing in the first place, and how this should be clustered into appropriate packages to share shutdown opportunities. A surprising number of organizations (particularly in the utilities and service areas of operation) still do not even know how much a shutdown costs them.

This article examines some recent advances in quantitative evaluation of shutdown programs. It looks at the bundling of tasks — the logistics of delaying some activities to coincide with others, and the compromise economics of shared downtime costs versus the performance and risk impact of premature or deferred work.

Orgins of the new approach
This methodology has been developed by the European MACRO project, a recently-completed five-year collaboration program sponsored by the British government, Halliburton Brown & Root, Yorkshire Electricity, The National Grid Company and The Woodhouse Partnership. MACRO has yielded a suite of methods for cost/risk/performance trade-off decisions — such as optimal maintenance or inspection intervals, equipment renewal or upgrade justification, shutdown strategy, spares requirements, etc. In each of these areas, a blend of innovative, risk-based evaluation techniques have been developed alongside structured guidance "rules". These have been developed and proven in field by those faced with the decisions (i.e. not some academic theoreticians).

What work is needed, why?
The first step is the systematic determination of the tasks that might warrant a shutdown in the first place. Here the methodology splits a "greenfield" from "brownfield" environment. If there is an existing regime of shutdowns, inspection cycles, etc., it is somewhat wasteful to rebuild the task list from scratch. However, even in such cases, a "zero-based" maintenance program (e.g. FMECA and RBI/RCM combinations) can be a good stimulus to challenge existing habits and preconceptions.

Reasons for tasks
The FMECA stage is fairly well evolved — albeit with some variations depending upon the existence of local historical data. One minor advance in this area, emerging from the MACRO program, is the observation that, for greenfield projects (with no operational experience), it is often easer to populate the list of potential degradation and failure modes in reverse — i.e. by mapping intended functions first, then listing functional failure consequences and finally brainstorming the failure modes that could result in such effects.

Where maintenance history exists, on the other hand, known failure modes comprise the "seed" information, from which to extrapolate and consider other potential (not yet observed) modes. Generic libraries or templates can also act as such seed material, provided that local conditions and potential failure modes are also considered.

The criticality (the C in FMECA) assignment to failure modes is a subject in its own right — a source of confusion or clarity, depending on where you stand. It is certainly needed, and in shutdown studies, we have found that the main decisions are determined by just five to 10 dominant failure modes and the tasks designed to address them. Identifying these critical items, however, is not easy. The American Petroleum Institute (API) Recommended Practice (580/581) on Risk Based Inspection (RBI) is predominantly a criticality assessment and prioritizing of failure risks. Structured risk-ranking workshops, involving operators, engineers and maintainers, offer less rigour but are, in many cases, just as effective in identifying the key drivers, often at a fraction of the cost.

Types of tasks
RCM is the most widely accepted set of rules for relating individual threats (failure modes) to the best preventive, predictive, corrective or detective tasks. The method is particularly suited to the complex plant with many different types of failure modes. Static equipment holds less variety — most maintenance is condition-based and the predominant concerns are "what inspection method, and how often?" API RP580/ 581 were developed specifically to provide such guidance. Both RCM and RBI can be exhaustive (and exhausting!) but various criticality— streamlined versions have emerged to focus on the bits that matter most.

Whatever the identification method, individual tasks fall into two groups for our purposes — cyclic activities (such as preventive maintenance, inspections and periodic replacements) and one-off tasks, (such as modifications, capacity upgrades or other changes). The one-off tasks are generally subject to the same evaluation and justification as other projects or capital investments, and their timing is a matter of cashflow/payback/NPV/IRR calculations. The disadvantages of delay represent continued levels of risk, inefficiency or constrained performance, diluted to some degree by the advantage of deferring major expenditure.

Cycle tasks, on the other hand, are much more complex to evaluate and optimize. They exist because of (actual or potential) deterioration and risks or performance that changes with time. This topic is covered extensively in the relevant MACRO modules — how to build a model of the cost/risk/performance trade-off and determine the optimal interval, the impact of premature or delayed work, and the sensitivities to any key data assumptions. In summary this involves:

1. Structured, quantified description of the degradation process, using range estimates wherever hard data is not available. This description is built around distinct families of quantification techniques:
- Reliability & risk (failure modes, probability patterns and consequences);
- Operational efficiency (energy, consumables, output volumes and quality);
- Lifespan effects (life extension, capital deferment etc.);
- Regulatory compliance (safety, environmental);
- "Shine" factors (public and customer impressions, employee morale, etc.).

2. Cost/risk performance calculations for alternative intervals — putting numbers to the familiar trade-off curves below.

3. Sensitivity testing to the extremes of possible data uncertainty (often variations by factors of 10 or more for the speculative elements).

4. Identification of key decision "drivers" (which assumptions have the greatest effect upon the optimal decision).

If justified, more detailed investigation of these key assumptions to determine the correct strategy is needed. In most cases, range estimates are enough to identify the optimal interval, and only when the "cost of uncertainty" is high will the additional research be justified.

The trade-off calculations vary with the components involved — in many cases there are several interacting failure modes, efficiency profiles and effects upon life expectancy all in the same evaluation. For example, an overhaul of a heat exchanger will consider tube leaks and blockages, performance effects of fouling and cumulative damage to the bundles due to cleaning. The analysis results reveal which factors drive the maintenance strategy, and how that strategy varies with equipment usage, operational criticality, fouling rates, etc.

In the case of inspection intervals, there is a further split in the modeling methods required. The predictive/condition monitoring inspections dominate in major process industry shutdowns to identify and track vessel and pipework corrosion or cracking. Functional testing or detective inspections, on the other hand, are those designed to reveal existing "hidden" failures — typical of protective or standby equipment. The MACRO procedures for quantifying and evaluating these two families of tasks differ in the questions that need to be asked, but then calculate the same cost/risk trade-offs for various task intervals.

Combining tasks — compromise decisions
The shutdown strategy is a compromise. Some tasks will be performed ahead of their ideal timing, others will be delayed to share the downtime opportunity. The risks and performance impact of delayed tasks, and the additional costs of deliberate "over maintenance" in others, both contribute to the price paid for a particular shutdown packaging. The degree of advantage, on the other hand, is controlled by the costs that can be shared as a result. The downtime impact (lost opportunity costs) often dominates such sharing advantage, but the direct costs (planning, facilities, labour, etc.) of shutting down and starting up again must also be considered. The critical path of component tasks will determine the bundle's total downtime impact — and this will vary with the degree of sequential or parallel working that is possible (as well as the discovery of defects that need corrective work, task overruns etc.). Uncertainty is often high but, like component task justifications, these bundle characteristics can be explored in "what if?" mode to determine if, and which, assumptions make a difference to the final outcome.

External constraints exist at both the individual task and shutdown bundle levels. Some inspections should occur at least tri-yearly, or that a maximum acceptable risk is 10-6 for a certain failure mode. This limits the range of allowable intervals for that task. At the bundle level, logistical, safety or resource restrictions might constrain the grouping of certain tasks. Such bottlenecks force a greater cost of compromise: a sub-optimal combination and timing for the work.

Another form of bottleneck is that introduced by the need for a task at short intervals while all other tasks can be performed substantially less often. This introduces the option of nested cycles (the other tasks being performed every two, three or more cycles of the short interval work). It also reveals the scope for design changes to de-bottleneck the requirements — eliminating the frequent shutdowns and extending run lengths. The analysis process itself calculates the net payback for such modifications or de-bottlenecking.

The grouping and regrouping of tasks, and "what if?" exploration of de-bottlenecking, can be manual (combining tasks in different bundles and moving the bundles to shorter or longer intervals) or semi-automatic. The MACRO R&D work has researched a number of methods for the latter — including Artificial Intelligence techniques such as neural networks, genetic algorithms and simulated annealing. The final combination is still being refined — but the various prototypes have yielded some astonishing results. In short, the scope for re-bundling tasks and timings is much greater than expected, with corresponding substantial impact on costs, performance and risk exposures. The National Grid Company in the UK did some early work using a genetic algorithm approach, and revealed scope for 21 percent improvement in system availability, at the same time as a 23 percent reduction in total cost/risk impact. Since then, ICI Eutech has been using the methods to evaluate shutdown intervals for chemical manufacturing plant (revealing the Canadian equivalent of $5 million in savings), and my team have been re-bundling the maintenance and inspection tasks on process plant, railways and water utilities. In one such case, shutdown intervals were extended from two years to four years, releasing over the Canadian equivalent of $10 Million/year in net improvement.

The National Grid Company in the UK did some early work, using a genetic algorithm approach, and revealed scope for 21 percent improvement in system availability, at the same time as a 23 percent reduction in total cost/risk impact. Since then, Eutech, the consulting arm of the European chemical firm ICI, has been using the methods to evaluate shutdown intervals for chemical manufacturing plants (revealing the equivalent of $5 million in savings), and my team have been re-bundling the maintenance and inspection tasks on process plant, railways and water utilities. In one such case, shutdown intervals were extended from two years to four years, releasing an estimated $10 million per year in net improvement.

CASE STUDY: Power distribution circuit
Here, the shutdown (or "outages") comprise a variety tasks on the connected assets of a critical supply route. These could involve up to 30 or 40 discrete items of equipment in the circuit, and each item (for example the circuit breakers at each end) may have several tasks assigned to it, with optimal intervals that vary from short (six to 12 monthly) to long (some only every 12-15 years). The circuit outage program is a complex blend of small-and-frequent, and larger-but-rarer tasks, with a vast number of permutations possible. Some tasks are required by law, others can be brought forward or delayed. The cost/risk impact of delay varies greatly with the deterioration rates — some items have critical timing and other have fairly 'flat' curves of total impact.

The analysis process calculated the net present value (NPV) of all future costs, risks and outage timings and, in this case, the optimal regime involved bringing forward several of the 'next maintenance due' dates to create a better alignment. The subsequent avoidance of multiple outages more than paid for the earlier initial expenditure.

CASE STUDY: Chemical production unit
In May , 2000, the above-mentioned ICI Eutech presented a paper to the MACRO results seminar on results achieved in studying a bulk chemical manufacturing plant. An existing bi-yearly shutdown typically involved approximately $700,000 and involved 21 days of downtime. The criticality analysis revealed which units were the main drivers for the shutdown — the HCl stripping column, the reactor unit manway lining, some sacrificial iron packing in a column and some of the smaller piping. It was noticeable that these items were NOT the biggest, most expensive items to inspect or maintain, but were deterioration rate limiting — the component tasks necessary to inspect or maintain them had the shortest intervals.

The elimination of some of these run-length constraints (bottlenecks) involved, for example, using high performance alloys (Monel) to achieve longer life. The payback for such additional periodic cost was revealed be measurable in months. The study revealed that a shutdown could be achieved once every four years, with NPV savings of more than $5 million.

CASE STUDY: Conversion reactor and condenser
In 1999, the Woodhouse Partnership was involved in a similar study ?± looking at the possible extension of run-lengths for a specialized reactor/condenser process. The initial criticality assessment took three days, using a combination of structured interview techniques and survey of existing FMEA and QRA studies. This revealed a potential 'decision driver' list of about 30 items, each with a number of inspection and/or maintenance tasks required. In addition, there were a few one-off tasks that were accumulating — technology upgrades and mandatory modifications that needed to be scheduled into the program. The following items were identified as the most influential in the shutdown decisions:

- Reactor vessel: internal support beams, injector nozzles, shell integrity
- Quench tower: internal supports, nozzles, shell integrity, relief valves
- Re-circulation pumping system: gate valves, seals, cooler
- Product chiller: cleaning cycle, bypass unit
- Separator unit: relief valves

Working from the shortest cyclic tasks outwards, we created individual cost/risk/performance models by interviewing operations, maintenance and engineering staff, recording their experience, opinions and extrapolations (how the equipment would behave if we extended the intervals). The resulting range-estimates were explored for all sensitivities, so that the recommendations included the future data requirements for further refining the strategy. Over 75 optimization studies of component tasks were performed to create the necessary raw material for the shutdown optimization. This took three weeks for a team of four individuals (two full-time and two part-time).

The component task studies themselves revealed the scope for substantial cost/risk/performance improvement. Around $2 million per year in savings were identified from a number of minor changes in work scope, in timing or design/operations changes. These included, among several other recommendations:
- Upgrading materials for the reactor support beams;
- Changing the cleaning process for the product chiller;
- Installing dual pilots on the relief valves (allowing on-line maintenance);
- Stainless steel lagging of injector nozzles.

The big prize, however, was the extended interval between major shutdowns. The de-design changes and bottlenecking allowed a doubling of the shutdown interval, with net total impact worth a further $8 million/year across the six units. This figure comprises the net effect of increased availability, reduced maintenance costs, all changes to risk exposures, performance impact and even projected changes to equipment replacement requirements. It is the conservative sum of the 'pessimistic' projections, so we can be confident that:
a) the real benefits are substantially higher than this and,
b) the proposed strategy is appropriate even in the extreme case of projected risk assumptions.

Conclusion

These studies are fairly typical — a combination of some hard facts, a lot of range-estimated speculation, a long list of potential influences but relatively few that really matter, and complex interactions between failure modes, deterioration assumptions, design options and maintenance tasks. It has confirmed, however, that structured approach, combined with modern "what if?" optimization tools, hold substantial scope for increased performance and cost/risk improvement.

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John Woodhouse has 20 years experience in cost/risk optimization. His activities include designing and implementing change control procedures, optimal maintenance reviews, inspection strategies and company-wide training initiatives. John can be reached through his UK-based company, The Woodhouse Partnership, at www.twp.co.uk.