Research & Best Practices

Difference Between Preventive vs. Predictive Maintenance

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Maintenance is an integral component of operating manufacturing equipment.

You probably have some type of maintenance plan in place already, and it’s likely a preventive approach. Preventive or predictive maintenance are how most companies do industrial maintenance — and both are vastly superior to the third alternative — reactive maintenance, which essentially is addressing a piece of machinery only after it breaks down.

The key differences between preventive vs. predictive maintenance are:

  • Preventive maintenance occurs on the same schedule every cycle — whether or not the upkeep is actually needed. Preventive maintenance is designed to keep parts in good repair but does not take the state of a component or process into account.
  • Predictive maintenance occurs as needed, drawing on real-time collection and analysis of machine operation data to identify issues at the nascent stage before they can interrupt production. With predictive maintenance, repairs happen during machine operation and address an actual problem. If a shutdown is required, it will be shorter and more targeted.

While the planned downtime in preventive maintenance may be inconvenient and represents a decrease in overall capacity availability, it’s highly preferable to the unplanned downtime of reactive maintenance, where costs and duration may be unknown until the problem is diagnosed and addressed.

Below, we’ll look more closely at the differences between preventive and predictive maintenance and explore the benefits and challenges you should consider when choosing between them. First, let’s set a baseline definition for each of these:

Reactive Maintenance

Reactive maintenance — also known as corrective maintenance — is the most basic building block of a fully-formed maintenance strategy. This type of maintenance occurs in response to equipment performance degradation or breakdown and is typically carried out only after performance issues have been detected.

For this reason, reactive maintenance is considered the least efficient type of maintenance. By its nature, it happens only once equipment has stopped working up to spec (and in most cases, has stopped working altogether). This type of maintenance creates further inefficiencies in that it is not planned for or strategized and, thus, may occur even at the most inconvenient times for the facility.

While reactive maintenance often cannot be eliminated, it can become a minor portion of a maintenance strategy once more effective types of maintenance — described below — have been implemented.

Preventive Maintenance 

You’re most likely familiar with preventive maintenance (PM). The theory behind preventive maintenance is to take regular steps to prevent problems before they occur. Preventive maintenance has several characteristics:

  • Is planned at regular intervals
  • Requires machine downtime to carry out
  • Often consists of a checklist including equipment and component inspection, calibration, cleaning, repair and replacement
  • May occur at different intervals — your facility may have a daily regimen of machine cleaning and inspection at the beginning and end of shifts cycles and may also have more comprehensive semiannual/annual checks
  • Occurs even if identifiable issues are present

Essentially, preventive maintenance is a collection of best practices and averages that zeroes in on an identified interval that gives you the best odds of catching issues before they start. It continues to be practiced because it is highly effective for many organizations.

Predictive Maintenance

Predictive maintenance (PdM) is a growing field with options for connectivity and data collection continuing to be developed. In fact, the McKinsey Global Institute reports that implementation of PdM practices across manufacturing will have a $240-$627 billion cost savings across on the industry. Like preventive maintenance, it is a proactive approach. The main difference between preventive and predictive maintenance is that predictive maintenance utilizes condition-monitoring equipment to assess the performance of assets through a more real-time, data-driven approach, therefore, identifying the potential for issues before they occur.

While preventive maintenance relies on best practices and historical data, predictive maintenance takes measurements from machine operations as they are occurring and uses this data to raise red flags when indications of a problem are noted. In summary, predictive maintenance:

  • Is proactive
  • Can be performed as the machines are running in their normal production modes
  • Identifies and addresses potential problems, allowing maintenance to occur before a failure happens
  • Relies on interconnected measurement and data collection systems as well as tools and personnel to analyze that data 

Predictive Maintenance vs. Preventive Maintenance

There are key benefits and challenges presented by each type of maintenance, based on the qualities previously identified. Note that with two proactive approaches, some of the benefits will overlap.

Preventive Maintenance

Benefits:

  • Proactive
  • Limits unplanned downtime
  • Increases equipment lifespan
  • Is efficient, especially with experienced personnel

Challenges:

  • May be addressing problems that don’t exist — maintenance occurs regardless of identified issues
  • Requires more extensive inventory management for replacement components
  • Increases planned downtime

Predictive Maintenance

Benefits:

  • Proactive
  • Identifies actual issues early on so that they can be addressed
  • Shorter downtime
  • Improved inventory efficiency — parts are not run to failure, but are also not replaced while still usable
  • Presents extensive options for maintenance practices based on real-time analytics

Challenges:

  • More complex than preventive maintenance
  • Not as scheduled as preventive maintenance — downtime may still be considered unplanned though it is shorter, more efficient downtime
  • May require new equipment and technology infrastructure in order to collect and share data with a centralized system
  • May require additional personnel or training of existing personnel

Condition-Based Maintenance vs. Predictive Maintenance and Preventive Maintenance

As you explore options for improving your maintenance strategy, you are also likely to hear the term condition-based maintenance. This approach describes the use of machine monitoring sensors to collect and transmit real-time data about the current, up-to-the-minute health of the machine, enabling more proactive maintenance by addressing potential issues before they cause a failure and unplanned downtime.

This approach aligns to a predictive maintenance plan, where you are not waiting for equipment shutdown or malfunction to occur, nor are you carrying out maintenance when it is not necessary. By incorporating intricate, constant machine health monitoring through the use of sensor technology, you will likely see improvements in maintenance effectiveness and efficiency, with a corresponding reduction in costs and improvement in overall production output.

Are you in the process of determining which maintenance strategy is right for your manufacturing facility? If so, use the definitions and analysis above help you weigh the pros and cons of each maintenance practice. Typically, the most efficient answer is some combination of both.

Looking for further assistance to determine which maintenance approach makes sense for your plant? Contact us today to find out how we can help.

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