When to Rethink Preventive Maintenance Optimisation Plans

Maintenance work must focus on the systems, machinery and parts that will have the biggest impact on uptime, and that work must be performed correctly in as little time as possible with the least wasted effort.

To be both effective and efficient, a plant’s PM plans and schedules need to be reviewed and updated regularly. How frequently such plans need to be updated depends on the technology, age of the equipment, and so on, but every six months is a good place to start.

With the goal of reducing redundant PMs and reactive maintenance, here are some of the guiding questions to ask the maintenance team:

• Are we doing the right PMs?
• What are the biggest causes of unplanned downtime?
• Are we reviewing our PM plan and priorities regularly?

When unplanned downtime rises, or your PM backlog grows, those are signs that it’s time to review your preventive maintenance plan. We recently helped a client in such a situation do a pareto analysis of their biggest causes of unplanned downtime. While they had been completing all of the assigned preventive maintenance tasks on schedule, they discovered that they weren’t doing any PMs in the areas contributing the most to downtime.

Such misdirected effort happens all of the time, even with well-run maintenance departments. Production volumes and product mix are constantly changing. That’s why preventive maintenance plans and schedules have to be adjusted regularly. In addition, because resources are limited, adjustments to the maintenance plan can’t be just about adding more tasks and generating more work orders. The existing workload must also be reprioritised.

Best Practice: The PM Audit

An annual audit of PM plans can help make sure preventive maintenance work is prioritised correctly and performed efficiently. A PM audit can focus on a specific piece of equipment, a production line or a workcell.

Asking and finding answers to this series of questions can provide the necessary perspective to assign resources where they will have the greatest impact on performance.

1. Start by reviewing the current PM plan and ask why the work is being performed:
   • Is PM primarily for quality, equipment condition, calibration, regulatory, manufacturer warranty or other purposes?
   • What are the consequences of failure?
   • What is the basis for the current PM intervals? 
2. Next, look at the failure history and past work orders:
   • Can the PM intervals be extended? Should they be shortened?
   • Can the PM work be replaced by visual inspection, process verification, or a more predictive approach?
   • Can machine operators perform some of the maintenance work?
   • Is the PM work order linked to spare parts, tools and the work procedures and drawings?
3. Then, narrowing the focus further still, examine the PM work instructions themselves:
   • Are there clear directions for safety (lockout/tagout)? Do the instructions explain what to check and how to check it, the correct procedures, and the tool and other resource requirements?
   • Are the instructions detailed enough that they are repeatable from technician to technician?
   • Can any of the current tasks be simplified or eliminated?
   • How accurate are the estimated PM completion times?

Finally, how often is the PM work reviewed after it’s been completed? This task can be shared between the maintenance supervisor, technical managers and the plant manager. In addition to verifying that the right PM jobs are being done, and that they have been done correctly, the review process sends a message that maintenance work is important. As we described previously, a thorough evaluation of your current maintenance practices can help manufacturing executives and plant managers understand how you are currently performing, and where PM work can be improved.