November 7, 2022

| 4 min read

Preventive maintenance vs predictive maintenance

What is preventive maintenance?

The idea behind preventive maintenance (PM) is that by performing regular maintenance on equipment, you reduce the chances of that equipment failing. It’s the same idea as taking your car in for regular oil changes to preempt a total breakdown.

Preventive maintenance (also called planned maintenance or planned preventive maintenance) is driven by time, meter, or event-based triggers. It’s based on the assumption that a machine component will degrade within a given period of time which is common for its type. Under a preventive management approach, the relevant parts will be removed, replaced, or rebuilt on or before the expected failure point. To go with our car analogy, it’s the same as replacing your engine oil every 10,000 miles.

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Mean-time-between-failure (MTBF) statistics can help optimize the preventive maintenance management schedule to include inspections, repairs, and rebuilds. But preventive maintenance is more complex than just always running maintenance on all your assets. Maintenance costs money, and you need to make strategic decisions about where and when to use it to keep your facility running optimally. How a machine is used and how often it is used (as well as a number of other variables) directly impact the machine’s operating life and its components.

The main issue with preventive maintenance is that this approach can sometimes result in unnecessary maintenance.

What are some examples of preventative maintenance?

There are many techniques and methods for preventative maintenance. Some common examples include: Regular cleaning of assets and asset parts, lubrication, replacement of parts, and equipment repair.

What is predictive maintenance?

Predictive maintenance (PdM) differs from preventive maintenance in that it is determined by the condition of equipment rather than average or expected life statistics. Essentially, it tries to predict failure before it actually happens by monitoring the machine during normal operations.

So in our car example, predictive maintenance would require oil samples to be taken at regular intervals and the oil replaced when it degrades beyond a certain point, rather than replacing it every 10,000 miles.

This is also called condition-based maintenance. In many cases, when predictive analysis spots an issue, the repair can be scheduled at a time that minimizes the impact on production.

Overcome the challenges of predictive maintenance

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What are some examples of predictive maintenance?

There are six main forms of PdM technology. Below are their definitions and details of how they are used:

Vibration analysis

Vibration analysis is a technique used to identify and locate vibration sources. It can be used to identify the source of vibration, as well as areas of excessive wear. For example, if there’s excessive vibration in your assets belt line while it’s in operation, that indicates that something needs to be replaced or repaired (such as the belt itself or a part in the motor). This could save you hundreds or even thousands of dollars in repairs down the line.

Oil analysis

Oil analysis is a technique used to determine the condition of the oil in an asset. Oil analysis can also be used to determine if there are any contaminants in the oil.

Oil analysis involves taking samples of an asset’s lubricating fluid and then analyzing those samples so that you can get some idea about whether or not your equipment needs maintenance work done on it. For example, if your lubricating fluid has too many contaminants in it (e.g., dirt), then this would suggest something wrong with your equipment that needs fixing as soon as possible.

Thermal analysis

Thermal analysis (sometimes called infrared analysis) is a method of determining the condition of a component by measuring its temperature. In thermal analysis, a thermocouple is used to measure the temperature of the component being examined. The thermocouple has two wires with different metals joined at one end and can be placed in contact with the component whose temperature is being measured. The other ends of these wires are connected to a digital multimeter which will display the measured temperature on its LCD screen. There can also be sensors added to the machine for continuous feedback rather than manually through the multimeter. These sensors are often monitored by the SCADA systems if they are in place.

If for example, a component is seen to be increasing in temperature and getting too hot the thermal analysis will indicate that there is a problem and will visualize where the problem is occurring through infrared imagery.

Laser-shaft alignment

Laser-shaft alignment is a type of predictive maintenance. It measures the alignment of rotating shafts. Many types of rotating shafts can be aligned using this method, including: turbines, compressors, and motors.

Motor circuit analysis

Motor circuit analysis is a technique that uses a multimeter to check for voltage drop and current flow through the motor. The multimeter will measure the resistance of the wires and the insulation of the wires.

Ultrasonic analysis

Ultrasonic analysis is a non-destructive method of measuring the thickness and surface integrity of metal parts. Ultrasonic analysis can be used to detect surface defects in metal parts. Ultrasonic analysis is also used to detect flaws in metal parts that would not be visible to the naked eye, such as corrosion, pitting, and cracks.

What are some predictive maintenance techniques?

Predictive maintenance techniques are used to determine the condition of assets and estimate when maintenance should be performed. Some examples of PdM techniques include: Data collection and analysis, fault detection, mean time to failure prediction, and maintenance scheduling.

Preventative maintenance vs. predictive maintenance

Preventative maintenance

Predictive maintenance

Is considered to be Planned maintenance Proactive maintenance
Focuses on On the environment (people, tools, and processes) On the assets (parts and sensors)
Means to Prevent damage by performing timely repairs or replacements Predict when assets need maintenance
Uses Scheduling software to notify teams or individuals of upcoming equipment maintenance Predictive maintenance technology to address potential problems and schedule corrective maintenance before a failure occurs
Improves Asset performance and asset health Inventory efficiency since machine parts are not run to failure and are also not replaced too soon
Requires Machine downtime Does not often require machine downtime, and if it does, it’s generally short
Examples Part replacement and equipment repair Vibration analysis and thermal analysis

Establishing a maintenance program

The impact that random or unsuitable maintenance can have on your products and services, operating costs, and the bottom line is significant. You need to develop an overall maintenance approach that uses the appropriate technique for each asset.

Create better preventive maintenance strategies in 8 steps

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Tools like CMMS software can help you set up and adhere to a preventive or predictive maintenance strategy in a few key ways:

  • Tracking all your maintenance strategies in one place
  • Monitoring key performance indicators in your facility
  • Helping to determine when it’s more cost-effective to fix an asset or let it run to failure
  • Integrating with other systems, like ERP software, to get a full picture of your facility’s performance

Get your maintenance strategy under control

There are many different types of predictive maintenance and preventative maintenance techniques. In this article, we’ve tried to cover the most common ones.

Here are a few valuable resources to help you get your maintenance strategy under control:

  1. Condition based maintenance strategy
  2. How to choose the maintenance strategy that’s best for you
  3. A guide to CMMS metrics

Get a nine-step plan for modernizing maintenance

See it in The Business Leader's Guide to Digital Transformation in Maintenance

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Business leader's guide to digital transformation

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