Quantifying the future in two ways

ask jeff shiver quantifying the future in two waysQuestion: How many backlog work orders should we have? Is there a range, e.g., 100-150 work orders?

Syed, reliability engineer, FL

Answer: Hello, Syed. Consider that backlog is a forecast of future work documented in the CMMS system as work notifications or work orders. We typically separate the backlog into two categories: total and ready-to-schedule backlog.

Total backlog is all of the work in the CMMS system yet to be completed. Ready-to-schedule backlog is identified by a CMMS status indicating that the work has been planned and any materials and/or special tools are available. We are waiting for the asset or labor resource availability to place the work on the schedule.

When discussing backlog, it's important to recognize that backlog should be measured in terms of estimated hours as opposed to numbers of work orders. The reason is that the labor hours required to complete the work can vary dramatically from work order to work order. One work order can require one hour or less; another could be 200 hours in duration. To overcome this, I suggest that the planner, upon noticing a new work order in the backlog, take a quick (educated) guess to estimate the job's duration to help quantify the backlog. The planner later can provide a more-accurate estimate when planning the work. Granted, this does add a task to the planner’s workload. As a workaround, some organizations take a broad sample of the number of completed work orders and calculate the average hours to use as a multiplier with the number of work orders in the total backlog. Understand that this is an average. With the ready-to-schedule backlog having been planned, we should know the hours required for each work order.

Now take the available labor hours – ideally 100% of the workforce performing maintenance activities per week. Ignoring breaks and other reductions for this example to make it easy, consider that 20 individuals multiplied times 40 hours per week gives 800 hours of available labor. This is our capacity to perform work in each week. Now take the backlog hours by category and divide by the 800 hours of available labor. If you have 3,864 hours of total backlog and 1,884 hours of ready-to-schedule backlog, then you have 4.83 crew weeks of total backlog and 2.36 crew weeks of ready-to-schedule backlog.

Because backlog is a forecast of work, we trend each category to measure it. This trending will tell us whether we have adequate staffing for the forecasted work. Target 4–6 crew weeks of total backlog and 2–4 crew weeks of ready-to-schedule backlog.

What other insights do you have on this topic? Send me an email at the address below and I will respond or place your questions with my answers here.

Please post your comments so everyone can all learn.
Talk soon,
Jeff Shiver, CMRP

If you have problems in the fields of maintenance, reliability, planning and scheduling, MRO storerooms, or leadership as examples, please contact Jeff Shiver with your question(s) here.