The Continuous Improvement Blog

What's the difference between periodic and predictive maintenance?

Written by Colin McArdle on 10 Jan 2018

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Reactive maintenance focuses on fixing problems when they occur. But this ‘run-to-failure’ approach means you’re faced with periods of unplanned downtime that significantly affects the overall productivity and profitability of your company.

Production and maintenance teams striving to drive productivity and improved performance become frustrated with the lack of planning and the ‘it aint broke so don’t fix it’ mentality.

Preventative maintenance on the other hand, aims to minimise the possibility of equipment failures before they occur.

Preventative maintenance incorporates both periodic and predictive maintenance techniques. Though most businesses carry out periodic maintenance, many fail to dig deeper into why equipment fails, and use these learnings to increase the lifetime of equipment.

Period and predictive maintenance can be used alone or hand-in-hand.

But what’s the difference between them?

Periodic maintenance

Periodic maintenance (PM) involves regularly checking, cleaning and maintaining equipment to keep it running in optimum condition and at the performance level it was designed to operate at. Through regular scheduled maintenance, the chance of equipment failures are minimised, and the life span of equipment is prolonged.

Production and maintenance teams work together to plan PM activities that minimise production downtime, thereby leading to improvements in communication, collaboration, teamwork and employee engagement.

A PM strategy involves scheduling time to carry out tasks in ‘planned downtime’. Ideally, tasks are scheduled at times where minimum impact will be had on productivity, for example overnight, or at the very beginning or end of the day. And any tasks that will result in longer periods of downtime can be prepared for in advance.

Maintenance may be scheduled based on equipment breakdown history. Root cause analysis is carried out on equipment failures with error proofed solutions put in place to prevent the same failure from recurring and stopping production.

Tasks may also be scheduled based on calendar dates or usage, often at the recommendation of the equipment manufacturer. For example, many forklift manufacturers suggest performing maintenance every 150 to 200 hours of operation.

While it may be difficult to justify a ‘just in case’ expenditure, the money spent on minimising the possibility of problems occurring will almost always be less than the costs you incur due to actual failures.

Are you counting the cost of production downtime due to machine failures? Do you know how much it costs to stop production for 10 minutes to repair a machine fault?

A PM approach is not without challenges though. Equipment operating continuously around the clock needs to be shutdown to complete essential maintenance tasks, which means some downtime is unavoidable. As a result, PM practices can be costly.

In summary, there are some clear benefits of periodic maintenance (PM):

  • Increases equipment life span and returns on capex investment
  • Cost effective by eliminating and preventing equipment failures
  • Improves and maintains productivity levels
  • Reduces unplanned downtime
  • Improves communications and teamwork

Predictive maintenance

Many businesses will have PM practices in place. But not all dig deeper by posing the question; could the failure have been detected before it occurred?  

This is where predictive maintenance (PdM) comes in. The aim is to use equipment manufacture reliability statistics such as MTBF (Mean Time Between Failure) and equipment part fault history to determine the probability of critical part (those parts within the equipment that will stop production) failure.

In doing so, you can predict when equipment failure might occur, and align maintenance tasks to be performed before they occur.

With continued technology advancements many companies are using techniques such as thermal imaging, vibration analysis, and oil analysis to predict failures. Thermal imaging, for example, allows you to use infrared to capture an image of your equipment and identify any ‘hot spots’, therefore pinpointing potential problems. Most of these techniques can be carried out during normal operations so no planned downtime is needed.

By monitoring performance you can see when problems are beginning to start and make repairs and replacements before actual failures. As a result, maintenance only needs to be carried out when required and production time is not impacted.

The Aerospace industry is highly regarded for its safety and minimal fatality rates due to equipment failure. What have they been doing to achieve these outstanding performance statistics? For many years they’ve been leading the way using PdM techniques and the industry continues to drive leading edge technological solutions to detect failures before they occur and predict in advance when they will occur.

Tackling the causes of equipment failure directly also means less time is needed to be spent on preventative maintenance tasks. In theory, PdM minimises the possibility of a failure occurring to as low as possible.

However, it can be complex and it involves a higher initial investment than preventative maintenance. But if implemented well, the ROI can be significant.

In summary, the benefits of predictive maintenance (PdM) are:

  • Condition checks can be carried out while equipment is still running
  • Real-time equipment information drives repair and maintenance activities
  • Identifying potential failures means repairs can be made before equipment stops
  • Uses equipment part reliability data and failure history to predict failures
  • Reduces overall cost to maintain as equipment is not under or over-serviced
  • Provides full visibility of how equipment is operating

The main difference between the two approaches is that PM may require equipment to be shut down, and PdM can be carried out while equipment is still running. 

Whilst there is no right or wrong approach to maintenance, leveraging the benefits of both PM and PdM strategies is often considered the most cost-effective way of maintaining equipment efficiency and preventing failures. The addition of PdM allows for the possibility of failures to be minimised as much as possible without straining budget with the implementation of too many PM tasks. 

Both strategies are important for any business wanting to employ a lean methodology and Total Productive Maintenance (TPM) program. Tackling process improvement starts from the ground up; with reliable and efficient equipment. To find out more about TPM, download our eBook below. 

TPM eBook

Topics: Total Productive Maintenance, Business Improvement

Colin McArdle

Written by Colin McArdle

Colin McArdle, the Founder and Managing Director of Kaizen Kulture is a Lean and Six Sigma Master Black Belt who has over 30 years industry experience. Kaizen Kulture's mission is to be true to the ethos of continuous improvement.