Equipment Reliability and Downtime

Dec. 23, 2015

Good cooks know what is in their pantry and improvise to come up with the best solution possible. We need to do the same and use existing systems to their maximum in order to get the data we need even if we must compromise a little. Work orders are a good example. We can set them up to collect a wealth of data and use them as the first and most important source of information about performance of our fleet.

Most, if not all, work order systems have the ability to code work orders in many different ways and have extensive routines that are able to track the status of the work as it progresses toward completion. Let’s look at how we can use these abilities to provide the data needed for two key metrics: reliability and downtime.

The type code and reliability

Work order codes are often defined by the user. It is absolutely essential to use one of the available coding fields to define a “type” or “reason” code for each and every work order. I recommend the following four and only the following four “type” codes:

• Black: The work order is issued because of an accident or operator abuse. The cost will not be charged against the machine and will be recovered elsewhere.

• Red: The work order is issued because the machine has experienced an on-shift failure. Repairs must be performed immediately; there has been or will be an impact on production.

• Blue: The work order is issued because a condition assessment or inspection program has identified the need for a specific repair before failure action. Work will be planned and scheduled to reduce production impacts to a minimum.

• Green: The work order is issued to perform a routine hourly, daily, weekly or monthly scheduled maintenance action. Work will be planned and scheduled to reduce production impacts to a minimum.

These work order type codes make it possible to:

1. Measure the effectiveness of safety and training programs designed to eliminate black work orders. Effective programs will eliminate the occurrence of black work orders.

2. Measure the effectiveness of condition-based and preventive maintenance programs. Effective programs will result in most, if not all, work being done on blue or green work orders and eliminate red work orders.

3. Enable us to define and measure reliability in a simple straightforward way: Reliability equals the number of red work orders per 1,000 hours worked.

The status code and downtime

Work order status codes are required to determine backlog and trace the progress of maintenance and repair work through the equipment organization. They are an essential part of the management process and help to ensure that work is planned and progressed efficiently.

I recommend that the following six status definitions should be used and that close to real time (daily) reports should be available to show the status of all work orders that have not, as yet, been closed:

• Pending: Starts when a red work order is opened in response to a reported on-shift failure, a blue work order is opened in response to an identified need, or a green work order is automatically generated in response to a trigger scheduled event. Pending work orders have not, as yet, been assigned to technicians.

• Assigned: Starts when a work order is assigned to a technician. No time has, as yet, been posted to the work order.

• In progress: Starts when time is booked to the work order.

• On hold: Starts when the technician indicates that work is on hold and no work will be done due to a shortage of parts or some other issue.

• Complete: Starts when the technician indicates the work on the machine is complete and it is ready to return.

• Closed: Starts when the shop manager has reviewed and finalized the work order. All costs are in, and no more costs may be posted to the work order.

These status definitions make it possible to define the following downtime periods:

• Repair downtime equals the elapsed on-shift time between pending and complete status for a red work order.

• Scheduled downtime equals the elapsed on-shift time between in progress and complete status for a blue and green work order.

It is extremely difficult to routinely record and agree on downtime in the field on an event-by-event basis. The work order type codes and status definitions set out above together with time card information do, however, make it possible to measure downtime in a systematic way that closely replicates the actual downtime experienced. Making a distinction between repair downtime and scheduled downtime and using the opening of a red work order as the starting time for repair downtime emphasizes the fact that on-shift failures impact operations right away. Using the in-progress status as the start of scheduled downtime for blue and green work orders means that time spent planning and scheduling work to reduce production impacts does not count against the machine.

Reliability and downtime are two different concepts. One measures the frequency of down events and the other measures their severity. Both are important and both must be measured. Frequency often serves as a lead indicator for severity, and emphasizing the reduction of frequent down events no matter how severe pays great dividends.

The type codes and status definitions described here will enable us to obtain the data we need to calculate two important metrics by making relatively small adjustments to the implementation of a competent work order system. The benefits far outweigh the costs, and there is no reason at all why we should not measure reliability and downtime on a regular basis. Our work order system and competent software enable us to get the required ingredients into our pantry.

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About the Author

Mike Vorster

Mike Vorster is the David H. Burrows Professor Emeritus of Construction Engineering at Virginia Tech and is the author of “Construction Equipment Economics,” a handbook on the management of construction equipment fleets. Mike serves as a consultant in the area of fleet management and organizational development, and his column has been recognized for editorial excellence by the American Society of Business Publication Editors.

Read Mike's asset management articles.