A Measured Approach To Uptime
Article by Hank Bardel of Marshall Institute - Read Article on Plant Engineering
Use Proactive Methods And Metrics To Prove The Value Of Maintenance
"I spent X number of dollars last year on maintenance, but don’t know what I got for my money."
"The facilities are running, but I don’t know if the money I am spending is the correct amount."
These are common responses by senior management about their maintenance department and activities. Maintenance managers frequently fall short of answers for these questions too. This typically means that they have no metrics that highlight the contribution of maintenance. Unfortunately this means that the decisions made by Sr. Management in these organizations concerning maintenance are being based solely on the cost of doing maintenance instead of the "value added" activities available to maintenance organizations.
These value added activities include, preventive maintenance (PM), predictive maintenance (PdM), planning and scheduling of maintenance activities, etc.
The absence of metrics
Metrics should equate to a defensible position for all resources currently used to maintain the facility. This position starts with the understanding that the job of maintenance is to maintain equipment efficiently and effectively. Failure of the equipment to perform its intended function, for any reason, is unacceptable.
A lack of even the basic metrics, such justification for the current number of maintenance craftspeople or the storeroom materials used for repairs, can lead to poor decision making. Without understanding maintenance and seeing the appropriate metrics, maintenance costs are controlled by reducing maintenance craftspeople (or headcount) and materials, or both. Unfortunately the negative impact of this decision is not immediately realized. There can be short term savings associated with this decision. However, this decision will eventually result in maintenance’s inability to do even the most basic processes needed to maintain the facility.
A downward or "death" spiral typically starts by missing PM’s, which allows normal preventable failures to occur. These failures result in a significant increase in work, specifically emergency work (which is 3-4 times more expensive than planned maintenance.)
The result is missing predictive (PdM) and preventive maintenance (PM), or maintenance planning and scheduling, which leads to more failures. More costs, lower production rates and increased quality problems typically occur. This is obviously not the intent of Senior Management but rather a consequence of their decision. "Best of the Best" companies have learned that it is not the number of craftspeople you have that really matters; but it is what you accomplish with those people.
A reactive maintenance scenario
The following scenario shows the affect of reactive maintenance on production and costs. It is 9 a.m. Monday, and production calls maintenance to inform them a machine is down and production has stopped. Maintenance accomplishes the following four activities:
Respond to Call....................................15 minutes
Troubleshoot the Problem......................30 minutes
Obtain Repair Parts (if available).............45 minutes
Make the Necessary Repairs.................30 minutes
Total Machine Downtime.......................120 minutes
- Respond to Call— The 15 minute response time represents maintenance personnel being productive in the field at the time the call is received. Many people’s response to this is "it shouldn’t take that long to respond to a call". However, if maintenance is able to respond immediately, what were they doing before the phone rang, just sitting around being unproductive? If so, this strategy is unacceptable and reactionary.
- Troubleshoot the Problem—The typical troubleshooting time is 30 minutes. This is not the best case scenario where a craftsperson sees a broken chain on the floor, or the worst case scenario of a craftsperson troubleshooting an electronics timing issue that could have taken hours to diagnose.
- Obtain Repair Parts—Identifying the spare parts needed for repairs can be very time consuming and expensive since the production downtime clock is running. In addition, once the parts have been identified the issues of getting them can be challenging, especially if expedited from outside the facility.
- Make the Necessary Repairs—With parts in hand, a craftsperson can now make the repairs and return the machine to operations.
- Total Machine Downtime—If the production hourly downtime cost for the machine is $2,000 per hour, this equipment failure cost the company $4,000 in production downtime costs alone. There would be additional costs for the maintenance time and materials used. Since this is a run-to-failure job there is a possibility of more damage to the equipment, which is referred to as collateral or secondary damage. From the operations side, most companies allow their operators to take a break while the machine is down. This strategy can lead to operators accepting failures and breakdowns so they can take a break. In the world of maintenance excellence, the 30 minute repair time is the only part of the job that is considered productive. Other aspects of the job are necessary, but not productive.
A proactive maintenance scenario
Organizations that practice proactive maintenance excellence focus on production uptime, equipment availability, product quality, and productivity of the maintenance craftspeople, rather than fixing equipment. Proactive activities include such things as a robust PM program, utilization of PdM technology, planned maintenance, work order control, and maintenance inventory control. Having metrics to show the positive impact of these activities is important, and moves maintenance’s reputation from being a "necessary evil" to a "value added" contribution.
Using the same scenario we used earlier, let’s now apply proactive maintenance principles and practices to identify the contribution of maintenance. In order to accomplish this, maintenance must have a robust PM/PdM process in place to detect minor abnormality before it becomes a problem and leads to failure.
The abnormality discovered during the PM/PdM inspection is converted to a maintenance work order. The work order is turned over to a Maintenance Planner/Scheduler. During the planning process, the planner starts with the work order and adds a procedure of how to do the work. This procedure contains a tool list, parts list, any sketches or prints necessary, required permits, and an equipment manual, if deemed necessary. The work order is then scheduled for a specified date and time.
Respond to Call..................................0 minutes
Troubleshoot the Problem....................0 minutes
Obtain Repair Parts (if available)...........0 minutes
Make the Necessary Repairs...............30 minutes
Total Machine Downtime.....................30 minutes
The best metric to show the contribution of maintenance in this scenario is equipment uptime. There are also several measures that can be used to show an increase in production uptime. This can be as simple as dividing equipment actual operating time (due to maintenance related issues) by scheduled operating time, or as complex as measuring OEE (overall equipment effectiveness).
- Response to Call—Response time as it relates to production downtime is zero. The machine will not be shut down until maintenance is there and ready to start.
- Troubleshoot the Problem—Troubleshooting time is zero since the PM/PdM process has already determined what needs to be repaired. The PM/PdM time is not included in this scenario since it is possible that the PM could have been done without machine downtime and PdM usually requires the machine to be in normal operation.
- Obtain Repair Parts (if available)—The maintenance planner has had the parts "kitted" in the store room and either delivered the parts to maintenance or the job site.
- Make the Necessary Repairs—The worst case scenario is the machine will be down for 30 minutes while repairs are being made. This planned maintenance could have possibly been scheduled for a time when the machine was not scheduled for operation. If this was possible, no downtime for maintenance repairs would be incurred.
- Total Machine Downtime—Total production downtime cost and worst case scenario for this planned and scheduled maintenance would be $1,000. This would represent a savings of $3,000 in production downtime cost over the reactive/run-to-failure maintenance scenario, and 1 and ½ hours of gained production time.
Another effective measure is Mean Time Between Failures (MTBF), this can be calculated as either the number of production units produced divided by the total number of equipment failures, or total operating time divided by the number of equipment failures. Additional metrics that will show the impact of maintenance excellence activities are:
Complete understanding of this maintenance excellence concept by Sr. Management is critical to the maintenance organization. This understanding will shift the focus from maintenance cost control to the necessity of having the resources and time to perform "value added maintenance" activities.
- Production rate (unit cycle times)
- Quality Rates
- Increase in capacity of the operations
- Contributions’ to productivity (operations & maintenance)
- Increase in Equipment Life Cycles.
For example, the focus will shift from the small dollar savings of $50 per hour per craftsperson cost (full burden rate) to the proper focus of $2,000 per hour in production downtime cost. Therefore it is imperative that the maintenance department develop the metrics that show the benefits of performing this type of maintenance excellence activities.
A win/win situation – shown above - results in lower costs and improved operations, and answers the question, "what am I getting for my maintenance dollars. Understanding maintenance excellence is critical; it shifts the focus from maintenance cost control to having the resources and time to perform value-added activities.