Failure has become a part of every industrial culture around the world; it permeates everything we do in an industrial facility. It is so much a part of our existence that we create elaborate work management and data systems to manage the sheer volume.

It is time to change our paradigm to a culture where failure is the exception and certainly not the rule. This is easy to say but a bit more of a challenge to accomplish.

The first step is to no longer accept the inevitability of failure. We have become conditioned to accepting the fact that failures must exist. We develop sophisticated measurements to track them, but very little is done to truly wage war on them. We ask our plant personnel to take copious notes on failures so we can track every detail of their existence, but after all that effort, what have we accomplished?

I propose a simple, yet extremely effective, eight-point strategy to wage war on the events we commonly know as failures.

Identify and document failure
The first step in the process of battling failures is to know where they are hiding. If we were to ask a group of people from the same plant what their most significant failures were, we undoubtedly would get a variety of answers. We rarely know where our most significant issues are. If we do not actively collect failure data as the events occur, we will be stuck in the cycle of a phenomenon I refer to as the "failure of the day." This type of failure is usually politically motivated and refers to failures that are fresh in peoples' minds.

Experience, however, has proven that the "failure of the day" is rarely the most significant issue confronting the plant. In order to truly know what failures are the most significant, we have to do a thorough job of collecting data on the failures as they occur. This way we can measure a failure's impact over time in comparison to all other failures that exist. As a famous management consultant once said, "You can't improve what you can't measure."

Imagine a person going on a diet but not being able to measure whether he's losing any weight; he could quickly lose momentum and revert to old eating habits. This is precisely what happens in an industrial plant. We collect data inconsistently and, even worse, we do not use the data to affect positive change.

Determine failure's real significance
Maintenance cost is not a true reflection of a failure's impact, although this is not apparent from the incredible amount of effort that goes into estimating its impact. Is a plant in business to reduce maintenance cost or to attain production level goals at the lowest possible unit cost? Most managers probably would be in favor of the latter, but maintenance cost is a very small factor in determining a failure's true business impact. We need to factor in not only the cost of repair but also the cost of lost opportunity. If a failure does not affect the ability to produce product, it is not nearly as significant as a failure that disables the ability to meet production schedules and customer orders.

Imagine a failure that has a maintenance repair cost of $100 but causes a day of production loss. If we look only at maintenance cost, we potentially would be missing a huge opportunity for improvement. Many initiatives to reduce maintenance cost have a negative effect on production. We tend to eliminate proactive maintenance activities that help produce at higher levels. Once again, what are the business goals: reduced maintenance cost or increased production and lower unit cost?

Focus on the top 10 failures
Once the most significant failures have been determined, it is critical to create a plant initiative to eliminate them. Plant management needs to embrace the philosophy that unplanned failures will not be tolerated.

They also must provide time and resources so teams of analysts can study these most significant failures on an ongoing basis. These teams should be comprised of source experts in each failure and led by an impartial facilitator. Each team should be assigned a single significant failure to analyze and should provide management with a team charter of what it plans to accomplish. Once the charter is approved, the team will be accountable for determining the underlying causes of the selected failure and developing a detailed plan for their elimination.

Use root cause analysis
Left to their own devices, the teams will surely stray, so they should be armed with a disciplined approach to root cause analysis (RCA) that has a track record of success. The RCA method should be accompanied by a software solution that will guide teams through the process. Using a software tool will help teams be consistent in their results and in their reports of their findings.

Pundits that downplay the effectiveness of RCA software solutions argue that a software tool cannot have all the possibilities for every type of failure event. I would agree that software should be used only as a way to adhere to the discipline of the methodology and as a way to effectively communicate and archive the findings and recommendations from an analysis. Many plants do a relatively good job of performing RCA but then store their analyses in a folder on a shared network drive or in a filing cabinet that virtually no one can access. I believe there is much to be learned not only in a single analysis but also across many analyses.

Consider a scenario where misalignment is uncovered as a root cause on five separate RCAs. Typically, this would indicate a more pervasive issue, but easily could be overlooked without the ability to query RCA results across analyses.

Develop effective strategies
Most RCA efforts fail not on the execution of the analysis process but on the execution of the corrective action phase. Plant management must set the expectation that an analysis is not complete until an effective strategy is in place to eliminate the effects of the underlying root cause(s). Performing an RCA without effective follow up on recommendations is not only a waste of time but could even have a counterproductive effect on team morale.

Teams must present recommendations to plant management for their evaluation, accompanied by a detailed plan of costs on execution steps. Once the plan has been approved, resources have to be commissioned to implement it. The analysis team should not necessarily be assigned to implementing the corrective action plan, because a good analysis team does not always make a good implementation team.

Track Key Performance Indicators
The same system that was used to track failure events also can be used to provide the metrics that determine if analysis work is being effective. Key Performance Indicators (KPI) need to be generated and evaluated on a monthly basis. The metrics that are selected must be specific to the failure being studied.

For instance, if maintenance cost was the business driver behind initiating the analysis, then it should be tracked to measure bottom line return. In a continuous process plant, asset utilization is a key factor that typically drives the initiation of an RCA. Whatever the case may be, it is critical to the process to select the metrics that will demonstrate success and continue the momentum to solve other problems.

Celebrate success
As with any accomplishment, we need to celebrate when we achieve a level of success. This is a vital step to the RCA process that is easily overlooked. The majority of analysis teams are humble and modest groups that do not like to take public credit for their hard work. It is up to management to recognize these major accomplishments and sponsor frequent celebrations to encourage future success.

However, monetary or other large rewards can possibly have a reverse impact on the process. One team may feel that it did not get as large a reward for its accomplishments as another team, and bad feelings can result. Group celebrations and symbolic rewards, such as a team jacket or a baseball cap with the teams name on it, are well received and are less likely to cause conflict among teams. These rewards may seem insignificant, but these are the same types of rewards that have been used for over 30 years to promote improved safety in plants. Employees wear these rewards with the pride of their collective accomplishment.

Another lesson that we can learn from our plant safety achievements is the need to advertise and communicate our success. Most plants have a progress board at the front gate to communicate their safety record for all to see. Many meetings begin by talking about a safety issue. These techniques are very effective in communicating the need for improved safety.

We can learn from these techniques in communicating our RCA successes. We can publish an article in the company newsletter or industry trade magazine. We can post RCA team activities and successes on the company intranet. By effectively and continually communicating RCA activities, they are less likely to be perceived as the "program of the month" and become part of the plant culture.

Repeat the process
In the early 1990s we heard a lot about continuous improvement. That terminology stemmed from the quality movement in the U.S. and we always heard about the need to continuously improve. We do not hear this term quite as much today, but the concept still prevails. Once we solve a critical problem, there is always another concern to address. RCA on significant issues must be done on a continuous basis. We must change our culture to the mindset where failure is no longer accepted or tolerated.

Every person should view problem solving and plant reliability as a responsibility and part of his job. Just as we are responsible for our own safety, we also must take the same responsibility to make our plants reliable. MT

Ken Latino is a senior reliability consultant at Meridium, Inc., 10 S. Jefferson St., Ste. 1100, Roanoke, VA 24015; (540) 344-9205

Progressive plant executives, maintenance managers, and work planners have always wanted to have information about the condition of equipment assets at their fingertips when they need it. Unfortunately, it typically is scattered among separate information systems, one for each information type: work history, reliability data, vibration analysis, infrared thermography, oil analysis, control device monitors, and more.

It is difficult, if not impossible, to view the different information types on the same computer terminal, let alone compile and synchronize them into an integrated view or report on which to base intelligent asset management decisions. Even when the systems can be accessed from the same terminal, it usually requires separate programs using separate languages.

One solution to this predicament is the open protocol standard being developed by the Machinery Information Management Open Systems Alliance (MIMOSA), a trade association for the MRO solutions industry. The organization advocates and develops information integration specifications to enable open, industry-driven, integrated solutions for managing complex high-value assets.

E-maintenance
The power of having information when you need it facilitates sound asset management decisions that add value to the top line, trim expenses, and reduce waste. The contribution to the bottom line is significant, making development of an asset information management network a sound investment. The resulting network that integrates and synchronizes the various maintenance and reliability applications to gather and deliver asset information where it is needed when it is needed is called e-maintenance, which is a subset of e-manufacturing, and e-business.

Connecting islands of information
Interconnectivity of the islands of maintenance and reliability information is embodied in e-maintenance. These separate information islands are built using specialized proprietary systems that provide value because they are optimized for a specific task or tasks, and they provide best results and value for those purposes. However, their combined value can be multiplied significantly if they can be merged into an e-maintenance network.

The e-maintenance network can be developed from a collection of information islands in several ways: use a single proprietary system, buy a custom bridge, build a custom bridge, or use an open systems bridge. The following discussion outlines some of the advantages and limitations of each approach.

Avoid bridge building
One network development strategy is to purchase as many systems as possible from a single vendor and leverage the system connectivity and integration provided.

Advantages include:

• A single source to resolve system problems and incompatibilities
• Low risk

Limitations include:

• Possibility of not getting a complete off-the-shelf solution from one supplier
• Possible dependence on proprietary interfaces
• Each product may not be the "best-of-breed" solution
• Less customization

Buy a bridge
A pre-designed bridge offered by a supplier can tie applications together so they can exchange information. The bridge may connect one program to another program or link one program to several programs. The bridge supplier may be one of the application providers or a third party.

Advantages include:

• Lower cost because development costs are shared among all who purchase the gateway
• Lower risk than using internal information technology resources to build a gateway

Limitations include:

• Possible dependence on proprietary interfaces
• Greater risk if gateway depends on the relationship among the suppliers. If that relationship sours, then gateway may be in jeopardy.
• Continuous buying or funding of updates to the gateway for new system versions
• Less customization available

Build a custom bridge
Some limitations of a pre-designed gateway can be overcome by using an integration company or your own company's information technology group to build your own gateway. However, this route can be expensive.

Advantages include:

• High level of customization for plant needs
• Short-term strategic benefit to company

Limitations include:

• High risk due to unforeseen incompatibility issues
• High cost due to lack of multiple users
• Difficulty in resolving problems among application suppliers (possible finger-pointing)
• Possible dependence on proprietary interfaces
• High annual software maintenance cost. These costs typically run around 20 percent of original cost which translates to $100,000 annual maintenance costs for a $500,000 software integration project.

Use an open systems bridge
A number of the limitations inherent in custom bridge solutions can be overcome by using an industry standard gateway. In mature sectors, this translates into plug-and-play capability that allows a company's information services department to hook up any compliant product to the network.

Advantages include:

• Engineered plug-and-play system capability designed up-front into system
• No burden of on-going integration efforts
• More freedom to choose best technology from information supplier (plug and play)
• Creation of the information backbone of e-maintenance

Limitations include:

• Necessity for suppliers to support industry standard
• Standard gateway may not provide all the functionality of a custom interface, but a good open systems standard allows suppliers to add capabilities built on the standard.

Win-win scenario
MIMOSA's open systems specifications offer advantages to maintenance and reliability end users as well as technology developers and suppliers.

For users, the adoption of MIMOSA specifications will facilitate the integration of asset management information, provide a freedom to choose from a broader selection of software applications, and save money by reducing integration and software maintenance costs.

For technology suppliers, the adoption of MIMOSA specifications will stimulate and broaden the market, allow concentration of resources on core high-value activity rather than low value platform and custom interface requirements, and reduce development costs.

What is an open system?
According to the glossary posted by the Software Engineering Institute (SEI) at Carnegie Mellon University (www.sei.cmu.edu/opensystems/glossary.html), a specification is open if its interface is fully defined and available to the public and it is maintained by a group consensus process.

The SEI goes on to define an open system as a collection of interacting software, hardware, and human components:

• Designed to satisfy stated needs
• With interface specifications of its components that are fully defined, available to the public, and maintained according to group consensus
• In which the implementations of the components conform to the interface specifications.

It follows that open system architecture would be made up of components, both hardware and software, that are specified in an open manner.

A number of consensus-based specifications have been developed or are in development for information sectors that make up the e-maintenance infrastructure. Those information sectors, specifications, and consensus-building organizations include:

• Control systems and production schedulers: OPC; OPC Foundation and ISA–The Instrumentation, Systems, and Automation Society
• Engineering product data management systems: STEP; Standard for Exchange of Product Model Data, ISO 10303 STEP
• Enterprise resource planning (ERP) systems: OAGI; Open Applications Group, Inc.
• Condition monitoring systems: MIMOSA
• Maintenance scheduling (CMMS/EAM) systems: MIMOSA
• Plant asset management (PAM) systems: MIMOSA

MIMOSA is also working closely with the International Standards Organization (ISO). ISO Technical Committee 108--Subcommittee 5--Condition Monitoring and Diagnostics of Machines is developing an official international standard for machine condition assessment.

MIMOSA solution
Taken as a whole, maintenance and reliability information is extremely complex, much more so than most business sectors. The e-maintenance network must provide for the open exchange of equipment asset related information between condition assessment, process control, and maintenance information systems. The condition assessment sector must include the specialized data required by vibration, oil analysis, infrared thermography, and motor circuitry evaluation. All these disciplines are represented on MIMOSA technical committees.

Prior to MIMOSA, developers defined data fields to fit their own hardware and software systems. MIMOSA provides a standard set of asset management data fields in its Common Relational Information Schema (CRIS) that software developers can adopt for their open systems.

CRIS spans all technologies, with tables for site information, measurement data, alarms, sample test data, and blob data (binary large object fields for drawings and photographs). Special maintenance and reliability tables define fields for events (actual, hypothesized, proposed), health and estimated asset life assessment, and recommendations. CRIS has been posted on http://www.mimosa.org/ for public download.

MIMOSA supplier members whose products conform to CRIS have the opportunity to certify those products as MIMOSA Compliant. Two sponsor members have done so: Emerson Process Management–CSI division and Rockwell Automation–Entek.

MIMOSA has begun adapting CRIS to XML which is a common approach for data exchange between systems over networks, including the Internet.

Learn more, get involved
MIMOSA needs additional insight into user information needs, technical input for standards projects, volunteers for technical and administrative activities, and project funding. Visit http://www.mimosa.org/ to learn more. E-mail MIMOSA President Alan Johnston. Telephone MIMOSA Executive Director Tom Bond at (619) 226-2244.

The more technical details of information flow in the e-maintenance network will be covered in a future article. MT

Special thanks to Ken Bever, strategic project manager, Rockwell Automation–Entek, Milford, OH, for significant input to this article.

Robert C. Baldwin is editor of MAINTENANCE TECHNOLOGY Magazine, Barrington, IL

Premature failures of pulse-width modified (PWM) variable frequency drives (VFDs) serving supply and exhaust fan motors caused costly interruptions to the plant's automated paint process. When the company started to investigate these intermittent drive shutdowns in the paint house, 70 VFDs ranging in capacity from 30-400 hp were in service at multiple 2000 kVA low-voltage substations.

Throughout the preceding year, the plant had reported multiple shutdowns of the paint house VFDs with each event costing approximately $300,000 in downtime and lost production. In each incident, maintenance technicians had performed field diagnostic procedures to determine what initiated the shutdowns.

The technicians reported finding one or two blown fuses at the affected drive. They also tested and condemned one or more gate turn-off thyristors (GTOs) on the voltage-source inverters. The condemned GTOs and fuses were replaced and the drives were successfully restarted without further incident. Each event involved a different VFD and none of the drives had experienced more than one shutdown event. With plant maintenance technicians blaming the shutdowns on component failures within the PWM drives, they removed the manufacturer from the plant's acceptable bidders' list.

Harmonic problems identified
Subsequent engineering analysis, however, proved that the shutdowns were due to accelerated aging and premature failure of PWM drive fuses. The fuse failures were linked to high voltage distortion levels on low-voltage busses that resulted in erratic drive operation.

A Square D Engineering Services team, led by Blane Leuschner, P.E., identified harmonic problems through onsite measurements and harmonic modeling using the Alternative Transients Program (ATP). ATP is a shareware program developed in Canada and similar to one developed by the Electric Power Research Institute. Using ATP, the team resolved the problem by combining additional line impedance with the application of harmonic canceling techniques.

A Square D Powerlogic monitoring system comprising approximately 500 devices was already in place at the plant. That system was supplemented by temporary measurements with portable test equipment. Permanent electronic meters were located at main breakers in the plant's 480 V system. In addition to measuring about 200 power system parameters, these meters were capable of capturing simultaneous waveform data on each phase of voltage and current, with sample-rate resolution high enough to detect suspected power quality problems. In addition, portable versions of the same meters were installed temporarily at the input terminals of several drives.

Onsite testing showed that harmonic distortion at the low-voltage bus increased with increasing numbers of VFDs in operation, as expected. "Measurements showed that voltage distortion at the main buses approached 10 percent when normal levels of drives were operated," Leuschner said. "While this level of distortion exceeds the 5 percent total harmonic distortion (THD) level usually applied to low-voltage buses, it is below the THD level at which VFD problems are usually encountered."

Further onsite testing showed that VFDs currents measured at the drives were erratic and did not resemble the expected 2-pulses-per-half-cycle signature characteristic of PWM drives. The erratic current signature was unusual for a PWM signature and signaled an anomaly.

"The anomaly was high frequency harmonics, typically around 960 Hz, in the line currents," Leuschner said. "Analysis of computer simulations showed that the noncharacteristic current harmonics resulted from low circuit inductance and high voltage distortion due to the operation of VFDs on each bus." The high voltage distortion resulted in severe flat topping of line-line voltage, which limited the ability of the dc bus capacitors to charge. Low circuit inductance compounded the problem by permitting a high-rate-of-change in the VFD line currents.

Harmonics modeling and analysis
In order to analyze the system mechanisms at work in producing the unusual current distortion, the engineering team created an ATP computer model of the VFDs and a low-voltage power system. The simulation included a complex PWM model consisting of about 1000 circuit elements. Actual measurements provided the basis by which the team verified the computer model in order to ensure accuracy of the simulations and effectiveness of the solution alternatives.

"Initially, we based our engineering analysis on the reports by plant technicians that GTOs had failed during each shutdown event," Leuschner said. "The earlier conclusion reached by the plant was inconsistent with later onsite measurements and computer simulations. Those measurements and simulations didn't expose a power system event anywhere close to damage levels on the GTOs in the inverter section."

In addition, the drive engineers determined that drive design prevented GTO failure from drawing enough current to blow an ac fuse. The engineers asserted that the GTO location in the drive was not getting enough available fault current due to upstream circuit components such as diodes, dc bus, etc. None of the empirical evidence could explain why GTOs would fail unexpectedly.

Consequently, the team turned its attention to the GTOs themselves. They set out to determine how the GTOs had been damaged and if the damage was corroborated by laboratory testing under more controlled conditions than existed in the field under emergency circumstances. "We found out that none of the condemned GTOs had been re-tested under laboratory conditions," Leuschner said. "Neither were the GTOs subjected to forensic investigation that might have revealed their mode of failure."

He recommended that such additional testing be done. Why, the plant argued, would additional testing be performed, when the GTO/fuse replacements had apparently fixed the problem and returned the affected drive to service? The team replied that the replacements were only a stopgap measure and that, without testing to determine a long-term solution, degradation and premature fuse failure would continue.

Laboratory testing
The plant subsequently authorized more testing, which located only five failed GTOs. Tests were performed under laboratory conditions by the plant and by Square D to determine the mode of failure. Test results showed that none of the five GTOs was damaged, thus confirming Leuschner's analysis and proving that the GTOs had been condemned by mistake.

The engineering analysis then turned to the drive fuses. These fuses had indeed opened during the shutdown events—there was no question about that conclusion. With the GTO failure theory freshly debunked, plant engineers and Square D investigators wondered if the drive fuses might have been damaged during prolonged operation under erratic harmonic currents.

"Our team searched published articles on the subject in search of a precedent, but found none," Leuschner said. "Yet, evidence suggested that the substantial high frequency content and dramatic fluctuation in peak current magnitude of the drive currents subjected the fuse elements to abnormal stresses and resulted in accelerated aging." That theory was supported when Square D measured other circuits in the plant and found that no fuse failures had occurred on a circuit where drive operation was stable. Investigators used two 400 hp drives already equipped with line reactors—which constituted the majority of the circuit load—to confirm stability.

Solution options
Following detailed computer simulations of the VFDs and power system, the team issued its prescription. The report indicated a combination of line reactors and phase-shifting isolation transformers would provide the most cost-effective solution to the problem.

Other typical solutions, such as harmonic filters and hybrid filters at the main 480 V buses, were considered and eventually discarded. "The harmonic filter option, a typical solution of choice in such a situation, encountered a common dilemma when harmonic filters are being considered for transformers with a high percentage of VFDs," Leuschner said. He explained that conventional shunt filters contain capacitance that increases displacement power factor on the applied bus. VFDs, however, typically operate at high displacement power factor, while producing high levels of harmonic current. Many VFDs on a bus means high levels of capacitance that can result in leading displacement power factor and overvoltage.

Further, ATP modeling revealed that harmonic filters would not resolve the erratic drive current phenomenon. Low system inductance was the major factor contributing to that erratic drive current, yet harmonic filters would appreciably change system inductance. Low inductance allowed the dc filter capacitors inside the VFD to charge erratically, resulting in the noncharacteristic ac current.

Simulation identified the optimum simulated-voltage and current distortion reduction and proved that the best technical solution was to increase system inductance seen by the VFDs. While line reactors alone could provide this inductance, the investigators also modeled delta-wye transformers to assess additional benefits. "We knew that even though harmonic current passes through line reactors and wye-wye or delta-delta transformers without appreciable phase shifting, delta-wye transformers have a different effect," Leuschner said. "Fifth and seventh harmonic components, which comprise a significant portion of VFD currents, are phase shifted by 30 deg of the fundamental by delta-wye transformers."

The resulting phase-shift of these two dominant harmonic components comprises currents that are 180 deg out of phase with fifth and seventh harmonics from nonphase-shifted drives. The combination of line reactors and delta-wye transformers contributed to significant cancellation of the aggregate fifth and seventh harmonic current contribution of all the drives.

Of the 66 drives in the paint house not already equipped with inductive isolation—four 400 hp drives had line reactors—only seven were equipped with delta-wye isolation transformers, while 50 received line reactors. Delta-wye transformers were reserved for VFDs with ratings of 200 hp and above, while 100 and 125 hp drives were provided with open-style reactors in the existing drive enclosure. Inductive isolation was not required on drives under 100 hp. Fuses that had not failed and had been replaced were changed due to suspected deterioration.

Results and conclusions
During its Christmastime shutdown, the plant implemented the recommendations for line reactors and delta-wye transformers. All equipment was installed and operating within a month. Bad, erratic voltage and waveforms were corrected into clean sinusoidal voltage and double-hump current waveforms. Harmonic voltage distortion was reduced to less than 5 percent. Drive currents returned to their normal signature.

"Our recommendations also identified the need for improved training of plant maintenance technicians," Leuschner said. "Much of the early confusion about the cause of the shutdowns could have been avoided by more accurate assessment during in situ testing of the GTOs." While the GTOs are difficult to test in situ, the plant implemented procedures to improve this testing, and to require that any electronic devices suspected of damage would be subjected to laboratory testing.

No further fuse failures have occurred since the modifications were completed, and the drivers' manufacturer was returned to the plant's acceptable bidders' list. MT

Information supplied by Square D/Schneider Electric, Palatine, IL; telephone (800) 392-8781

Robert C. Baldwin, CMRP, Editor

To me, their promotional materials invariably conjure up a picture of an executive peering at a computer terminal to find out what is happening. What is he looking at? An idiot light on the enterprise dashboard?

Perhaps you get another image when you hear "plant floor to top floor," but my first vision is of the big boss trying to manage a company from a computer terminal. What should top managers be doing? I think they are getting paid to focus on shareholder value and enterprise strategy.

If the leader has competent associates, then things run smoothly. A plant manager needs a competent operations manager and a competent maintenance and reliability manager. If they are doing their jobs, their boss can focus on the future and not have to get mired down in day-to-day activity.

The boss doesn't need an idiot light to tell him that his production engine needs servicing. He needs competent people who can operate it and service it effectively. And there lies the rub. Most of them don't have the information and systems to make them as effective as they need to be.

So what is really needed is horizontal communication on the plant floor. Without it, there isn't much to send up to the top floor.

Plant information typically resides in functional islands: operations, control, predictive maintenance, asset management, etc. They are all components of the information matrix needed for competent decisions. If they are not readily available, how will the plant floor know when to turn on the idiot light, or what color it should be?

Open standards will play an important role in building the information network for the plant floor and the enterprise. They free the builders to select components based on performance rather than pedigree. (We expect MIMOSA to be an important contributor to open information standards.)

In spite of my vision of "plant floor to top floor," I'm embracing it because it promotes action. Whether communications is best established top to bottom, bottom to top, or side to side, you have to begin somewhere. And once you start, you find that the value of the network increases as the product of the number of nodes, and everybody wins. MT

Leadership and crafts both want greater productivity in the execution of work. Leadership definitely wants to reduce waste and the dollars associated with it. Crafts want to utilize their time and skills effectively to accomplish equipment tasks professionally. Eliminating wasted time is good for business and good for general morale.

Typical wrench time ranges from 25 to 35 percent while benchmark levels range from 50 to 60 percent. What time-wasting issues make up this gap? From past Viewpoint articles you know that I see things through Six Sigma glasses. Using Six Sigma methodology, we can discover the set of circumstances that represent the gaps. Fundamental to Six Sigma thinking is that: Y (wrench time) = f (x₁, x₂, x₃, x₄, &).

What are some of the xs? How about stores delays, equipment preparation, work permitting, travel time, incomplete or wrong diagnosis, inadequate tools, waiting on the cherry picker, bad or wrong spare parts, inadequate work plans, and more.

The trained Black Belt or Green Belt will summon the disciplined Six Sigma roadmap: Measure Analyze Improve Control (MAIC). A team of cross-functional stakeholders will drive the effort to eliminate these daunting wastes. Some key MAIC tools include:

• Map the as-is process with operations and maintenance stakeholders. (There is an as-is process whether it is controlled or uncontrolled.)
• Define the inputs that make up the existing process. Are they controlled or uncontrolled?
• What outputs are really important to the process (in addition to wrench time)?
• Measure the defects and the current pro-cess capability (sigma, defects per million opportunities).
• Analyze the failure modes of key inputs.
• Mitigate the failure modes.
• Improve the process by mapping the should-be process.
• Install mistake-proofing tools at key steps (a.k.a. poka-yoke).
• Validate the improvements and measure the new process capability (sigma, defects per million opportunities).
• Establish measures and controls to ensure sigma capability is improving and sustained. Yes, statistical process control (SPC) can be used for work processes.

Of the bullets above, measuring becomes a key element of the effort to improve. How is the current process performing? Where are the wastes? How often do these wastes occur (frequency, or MTBF)? How severe are the waste events (time wasted, or MTTR)?

To answer these questions, a data collection method needs to be designed and deployed. Work sampling is one method. Another approach is to "follow the babies," as we say in Six Sigma; maintenance events (work orders) are literally followed from start to finish. It sounds simple, almost juvenile; but the team will be amazed by what it learns about how the current process works and what comprises the defects (wastes).

Once the measuring phase has been completed, a cadre of immediate quick fixes and opportunities (greater analysis required) will emerge. The opportunities likely will point to broken supporting processes (job plans, work permits, tool crib, outside services coordination).

None of these are simple processes with easy fixes. They likely will require a new, more detailed set of work-process improvement projects.

One of the truisms of Six Sigma is "you don't know what you don't know." Once you have data (now you know), it becomes very apparent that the interactions of maintenance activities are quite complex. If your wrench time is estimated in the 35 percent range, then your maintenance work process is broken.

What supporting processes are broken? You know that the brokenness is impacting the margin on the products you produce, and therefore can be classified a business driver for your company.