Measuring Reliability
Reliability of capital equipment is critical to the success of any manufacturing operation, mobile
fleet, facility operation or any combination thereof. How do you accurately go about determining
equipment reliability? Only when it is clearly understood that achieving a high level of
equipment reliability at a reasonable or competitive cost is ultimately the job of everyone in the
plant / facility – not just the maintenance department – can accurate and effective reliability
measurement schemes be developed.
While it is true that maintenance performance should be measured in terms of reliable capacity
within predetermined cost performance targets and estimated annual and monthly budgets
respectively, isn’t this also true of operations? Yet most people still believe that maintenance
alone controls reliability. When you consider that operations or production controls the
equipment through their operation of it, it becomes apparent that they in fact actually have a
much greater influence on equipment condition and therefore they also must be held accountable
for that equipment’s reliable performance. The fact is that in actual practice when operations and
maintenance are jointly responsible for equipment reliability the opportunity to improve is
significantly increased.
When measuring reliability, consideration must be given to the data contained in management reports. Specific performance indicators must be carefully established, measured and reported in order to provide operations and maintenance supervision with pertinent and detailed information that they can effectively use to manage their business unit. These indicators must be consistently and accurately measured and reported. Additionally, a higher level of detail, or summarization, of these indicators is required for senior or executive management and should be consistently reported weekly or monthly, with any supporting details available on request or during analysis.
Much of the data necessary to measure factors influencing reliability and budget performance is
available directly, or can be derived from, CMMS (Computerized Maintenance Management
System), assuming it is properly implemented and effectively utilized. Reliable capacity data can
be derived from operations records and electronic manufacturing control systems. Parts and
materials usage data can be derived from inventory control systems and purchasing systems in
the case where these functions are not performed within, or linked to, CMMS. Other useful data
can be derived from accounting systems, quality systems, time-payroll accounting and human
resource systems.
Accurately establishing current baselines of performance is an important step to begin with.
Once baselines are established, identify both short and long-range targets for all reliability
measurements that are defined. You must know where you are and where you want to go, or you
may not recognize it when you get there.
“Distinguish Management Data and Reporting Information”
Budget performance – Annual budgets of anticipated reliability activities should be estimated for each equipment item or asset each year and continuously monitored. A well-conceived equipment hierarchy in the CMMS that breaks down the facility by category can facilitate this process.
Some recommended breakdowns are:
• by area
• by system
• by machine or asset
• by component.
Cost data is then systematically and accurately collected for all labor, parts, materials and subcontracts at the machine or asset level via the Work Order System. Whether work is performed by operations or maintenance, it should be captured via the Work Order System. The CMMS databases must be completely and accurately developed to provide the basis for this approach. This level of detail is critical for supervision to establish and refine the proper level of budget control and identification of high cost equipment issues. This information can be rolled up to a higher level by area, by system, or for the total plant/facility for executive or senior management reporting. In proactive maintenance operations, a total planned cost estimate for each maintenance job is prepared whenever possible. The estimate should include labor, parts, materials, purchase requirements and subcontracts. Comparisons of actual cost to estimated costs by job provides the basis to measure performance of maintenance crews or operations personnel as well as a means to control budgets and continuously refine future cost estimates.
Cost per Unit of Output – Measuring manufacturing and maintenance costs in terms of output of the facility can be a very effective way of managing the business and monitoring budgets. These measures can be benchmarked to an industry standard or an internal standard and permit a concise and clear measure of performance, particularly if the data is trended utilizing a thirteen month rolling average trending analysis.
Some examples of costs in terms of plant / facility output are:
• cost per pound
• cost per ton
• cost per case
• cost per square foot (facilities)
• cost per mile (mobile / fleet equipment)
Capacity Measurements – Typically, the negative influences on reliable capacity are time losses, speed losses, scrap losses at start-up and quality losses caused by improper design, operation or maintenance. Take note that other departments within the organization can influence any of these parameters, either directly or indirectly. Many organizations focus solely on unscheduled downtime and proceed to measure it inaccurately to make the reported numbers visually look good or only focus on maintenance downtime, ignoring operations or scheduled downtime.
“The cost of downtime is the same, no matter what the cause”
A high level of unavailability without consideration of speed and quality losses can prove quite costly. The ultimate capacity measurement method is monitoring “Overall Equipment Effectiveness” (O.E.E.)
OEE = (Availability) x (Efficiency) x (Quality)
where:
Availability = total time minus delays divided by total time
Efficiency = actual speed divided by design or optimum speed
Quality = total output minus scrap or waste divided by total output.
This method lends itself to a manufacturing operation and it cannot effectively be utilized in mobile fleets or facilities. This method of measuring capacity, when cost of loss to the operation is analyzed for each parameter, can effectively be utilized to evaluate the risk of not performing the optimum level of maintenance or operating the equipment ineffectively as well as to justify the investment to improve performance.
Work Backlog – The total amount of work that has been requested or identified determines the maintenance backlog. All categories of work that estimates have been prepared for and trends of unplanned or emergency work and maintenance-performed projects define the backlog. Backlog must be segregated into logical work types, and then understood and managed in order to achieve effective resource utilization.
“Resources Must be Balanced with Work Load”
This information is very useful in determining the appropriate staffing level, overtime decisions or subcontracting. Work orders must be segregated into “ready to schedule” and (with status)“pending action required” (i.e., waiting on approval, waiting on parts/materials, waiting on shutdown, etc.). Including the status of pending categories allows continuous monitoring and can eliminate bottlenecks in the work control process. Total work backlog should not exceed 4-6 weeks and “Ready to Schedule” should not exceed 2-4 weeks.
Schedule Compliance – Each job should be scheduled, usually in the week prior to the week of
execution, for a specific timeframe during the schedule period. Each job should also have a
defined scope of work; parts and materials should be identified and delivered to the job site, all
tools and equipment made available and any permits or special considerations prepared. All
available labor should be scheduled each week (capacity scheduling) based upon an analytical
method of establishing the number of available labor hours. Supervisors, who are responsible for
tactical work execution, should be held accountable for schedule adherence at the 85-90% level
each week.
Professional Planning/Scheduling can provide the means to assign each individual worker a full
workload each week and the supporting documentation to hold them accountable to achieve it.
Schedule compliance = actual hours required divided by scheduled hours.
P.M. Compliance – An effective Preventive Maintenance program is also critical for achieving a
reliable operation. The success of a P.M. program is dependent upon timely and consistent
execution, continuously evaluating the results and ensuring that a dynamic approach is taken
that focuses on changing the frequency or content of the P.M. when the desired level of
reliability is not attained. Operations and Maintenance should be jointly engaged in executing
the PM program. Consideration should be given to optimizing the use of condition-based
scheduling techniques as opposed to traditional time-based scheduling. Most conditiondetermining
routines are performed with the equipment operating, which can significantly
reduce scheduled downtime to perform time-based tasks.
P.M. Compliance is simply a measure of how many of the scheduled P.M.s are actually
completed on time or P.M.s completed divided by the number of P.M.s scheduled. Using the 10%
rule when determining on time completion is a good way to determine timely completion. The
10% rule is simply allowing a range of time for completion defined as: P.M. should be completed
+/- 10% of the scheduled frequency, i.e., monthly would be +/- 3 days, daily would be +/- 2.4
hours, etc. This is a high level measurement that should be reported to management on a routine
basis. P.M. Compliance should exceed 90%, and should not be confused with P.M completion
rate, meaning that the P.M. is completed, within schedule or not, should be 100%
There are a great many performance measures that can be utilized. Use caution to avoid the
pitfall of most businesses. They measure too many performance indicators and then have less
time to spend on analysis and on taking action to improve performance. When utilizing any
performance measure, a target must be established that defines best practice or ideal
performance and employees must be educated on what these targets mean and how their
performance influences the wellness of the business. The measures discussed here are not
intended to be an all-inclusive list, but a good place to start in measuring – and improving –
reliability in your plant or facility.
