Set your plant up with zero-backlog maintenance

April 9, 2007
Zero-backlog maintenance is in your future. It’s the state of optimal reliability in which more than 80% of work is proactive. It identifies and schedules the right work at the right time far into the future.

 Zero-backlog maintenance is in your future. It’s the state of optimal reliability in which more than 80% of work is proactive. It identifies and schedules the right work at the right time far into the future. The maintenance world defines backlog as the amount of maintenance work in labor hours in a specific status before it is scheduled. Zero-backlog maintenance changes the way you’ll view and manage maintenance.

No one seems to be presenting anything new in maintenance and asset reliability. I say the maintenance and reliability community needs to wake up. We need new concepts and ideas that optimize asset reliability at optimal cost. Zero-backlog maintenance is such a concept that’s in use today. Having no maintenance backlog and optimal reliability means your asset health indicators trigger work far enough in advance to allow planning proactive maintenance work. The world-class benchmark for maintenance backlog is two to four weeks-worth ready to be scheduled, and four to six weeks of total backlog.

Consider a dysfunctional maintenance operation. The focus is on responding to work requests, emergencies and equipment problems, often while performing additional preventive maintenance (PM) work. Someone, typically management, must verify and prioritize work requests. Maintenance is structured around writing (sometimes) emergency work orders. Preventive maintenance goes on even though it doesn’t prevent breakdowns. The main function of any predictive maintenance is to identify imminent breakdowns that even a novice realizes will occur very soon. Planning focuses on finding today’s parts and identifying parts for next week’s work because planners have few, if any, pre-planned job packages. Scheduling focuses on work to be done tomorrow, next week, or four to six weeks out at best. Execution is based on the technician’s experience and knowledge, which is rarely documented. This whole business is reactive, has higher costs and fosters unstable reliability and capacity.

Albert Einstein once said, “Problems can't be solved with the same level of awareness that created them.” Zero-backlog maintenance is going to require you to focus on mitigating failures using a strategy developed from known and likely failure modes. It involves a judicious mix of preventive, detective, predictive technology and a run-to-failure strategy based on risk and consequence.

Eighty percent of the work the maintenance planner handles will originate in asset health alarms that trigger a specific maintenance strategy. Preplanned work packages will include procedures, specifications, parts, labor requirements, tools and other items. Scheduling is based on the P-F interval, which detects the first inkling of failure six weeks, six months or further in the future. Such advance warning allows production to schedule outages based on sales forecasts. Work is performed to standards and specifications. The maintenance strategy is adjusted if an unknown failure occurs.

This represents a continuous improvement loop in the proactive asset reliability model. Mechanical failure will be relegated to the status of plant lore, remembered only by old-timers. The outcome optimizes reliability at optimal cost. It meets the company’s business goals through optimum throughput and asset availability. It minimizes process variation, thus reducing cost of goods sold.

Get started now. Rank your assets according to consequence and risk. Then, beginning with the highest-risk asset, specify a maintenance strategy that details the right work at the right time. Recognize that 80% of failures are random. Analyze known and likely asset failures to recognize when you’re facing a random failure.

Ensure your planner knows the interval between detecting abnormal vibration and the bearing’s functional failure. Develop a preplanned job package to prepare for that day. Performing the right work at the right time, not too early or too late, fosters zero backlog because 80% of your maintenance work is scheduled at the first detection of impending failure. Use a reliability software package to signal the planner when the “P” has occurred (this reliability software doesn’t replace your CMMS/EAM). Schedule work according to asset criticality.

The future is now, the solution isn’t, and not enough companies are exploiting this concept today. Zero-backlog maintenance uses proven methodologies to develop a strategy that detects when a failure begins to occur and identifies the interval between detection and failure. And, maintenance scheduling won’t affect production or operations.

E-mail Contributing Editor Ricky Smith, CMRP, at [email protected].

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