Maintenance is an integral component of operating manufacturing equipment.
Keeping your facility’s industrial equipment in good working order is essential, and ideally you want to make sure you address any minor issues before they lead to costly shutdowns. Utilizing predictive and preventive maintenance helps ensure you stay on top of everyday wear and tear.
Although these might sound like the same thing, they aren’t. Preventive maintenance refers to any work that’s done on a regular schedule, while predictive maintenance is performed on an as-needed basis.
Both approaches are designed to improve equipment reliability and reduce the likelihood of unexpected failures, but they accomplish these goals differently. Preventive maintenance relies on predetermined service intervals, while predictive maintenance uses equipment condition and performance data to help determine when maintenance is actually needed. Understanding these differences can help manufacturers use maintenance resources more efficiently while minimizing disruptions to production.
Which maintenance strategy will work best for your organization depends on your facility’s equipment criticality, failure risk, environment, workflows, maintenance schedules, and available monitoring technology.
In many facilities, the answer isn’t choosing one approach over the other. Preventive and predictive maintenance can complement each other as part of a broader maintenance and reliability program. Routine preventive tasks can address predictable maintenance needs, while predictive technologies can provide greater insight into the health of critical assets and help maintenance teams identify developing issues before they result in failure.
Read on to learn more about the differences between preventive and predictive maintenance as well as why both should be a key element of your facility’s operations.
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.
For example, a facility schedules monthly inspection and lubrication of conveyor motors. Even if no issues are detected, maintenance occurs to reduce the likelihood of unexpected failures.
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 is a growing field with options for connectivity and data collection continuing to be developed. Like preventive maintenance, predictive maintenance 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.
Common predictive maintenance tools include:
- Vibration monitoring
- Oil analysis
- Infrared thermography
- Ultrasonic leak detection
- Industrial IoT sensors
For example, a vibration monitoring system detects abnormal vibration in a motor bearing. Maintenance is scheduled before the bearing fails, helping prevent unplanned downtime.
Predictive maintenance vs. preventive maintenance
When it comes to preventive vs. predictive 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
How to decide between preventive and predictive maintenance
The right maintenance strategy depends on more than the equipment itself. Maintenance teams should consider the asset’s importance to production, its common failure modes, the consequences of failure, the ability to detect deterioration and the cost of monitoring compared with the cost of downtime or repair.
Start by asking several questions about each asset:
- How would production be affected if this equipment failed unexpectedly?
- Could the failure create safety, environmental or product-quality concerns?
- Does the asset tend to fail according to a predictable age or usage pattern?
- Are there measurable warning signs before common failures occur?
- Can those warning signs be monitored cost-effectively?
- How much does planned maintenance cost compared with an unexpected failure?
If maintenance requirements are predictable and the consequences of failure are relatively manageable, preventive maintenance may be sufficient. If an asset is highly critical and its condition can be effectively monitored, predictive maintenance may offer greater value by helping teams identify problems before they cause downtime.
Importantly, the choice does not always need to be made at the machine level. Different failure modes within the same asset can require different maintenance strategies. A motor, for example, might receive lubrication according to a preventive maintenance schedule while vibration monitoring is used to identify developing bearing or alignment problems.
Thinking at the asset and failure-mode level allows manufacturers to direct maintenance resources toward the activities that provide the greatest operational value.
If you are still unsure about which maintenance strategy will work best at your organization, talk with an ATS expert to learn which strategy is right for your facility’s unique workflows.
The role of asset criticality in maintenance strategy
Asset criticality can help maintenance teams determine where predictive technologies will have the greatest impact. A criticality assessment ranks equipment according to the consequences of failure, helping organizations prioritize maintenance resources rather than treating every asset the same.
High-criticality assets may include equipment whose failure would shut down a production line, create a safety concern, affect product quality or result in significant repair costs. These assets can be strong candidates for predictive maintenance, particularly when measurable indicators provide advance warning of failure.
Medium-criticality assets may affect production but have available redundancy, inventory buffers or other workarounds. Lower-criticality equipment may have little impact on overall operations and may be relatively inexpensive or easy to repair or replace. In those situations, traditional preventive maintenance, or a less intensive maintenance strategy may be more economical.
For example, a motor operating a production bottleneck may justify continuous vibration and temperature monitoring because its failure could stop the entire process. A noncritical ventilation fan with a readily available replacement may only require periodic inspection and scheduled lubrication. Matching the maintenance strategy to asset criticality helps ensure that technology, labor and maintenance spending are focused where they can deliver the most value.
Combining preventive and predictive maintenance
For many manufacturers, the most effective maintenance program is not exclusively preventive or predictive. Instead, the two approaches work together as part of a broader reliability strategy. Preventive maintenance provides the foundation for routine care, while predictive technologies provide additional insight into the condition of critical assets.
A practical approach to developing a hybrid maintenance program can include:
1. Create or validate an asset inventory. Identify the equipment that must be maintained and make sure maintenance records accurately reflect the assets operating in the facility.
2. Rank assets by criticality. Evaluate how equipment failures would affect production, safety, quality, cost and other operational priorities.
3. Review failure history. Examine work orders, downtime records and maintenance history to identify recurring failures and problem assets.
4. Evaluate existing preventive maintenance tasks. Determine whether scheduled tasks are effective, whether intervals should be adjusted and whether unnecessary maintenance is being performed.
5. Identify condition-monitoring opportunities. Look for critical failure modes that produce detectable warning signs through vibration, temperature, lubrication condition, ultrasound or other measurements.
6. Integrate predictive findings into maintenance workflows. When monitoring identifies a developing issue, there should be a defined process for evaluating the alert, planning corrective work and documenting the results.
7. Measure performance and continuously improve. Track metrics such as unplanned downtime, equipment availability, maintenance costs, recurring failures and planned versus unplanned work to determine whether the strategy is producing the desired results.
A hybrid of these two methods could include monthly preventive inspections, continuous vibration monitoring and predictive alerts that determine when additional maintenance is required. Condition monitoring can guide when additional intervention is needed, while scheduled tasks such as cleaning, lubrication, calibration or other routine work remain part of the preventive program.
Ultimately, the objective is not to maximize the number of predictive technologies deployed or eliminate preventive maintenance tasks. The objective is to apply the appropriate maintenance strategy to each asset and failure mode so that maintenance resources are used efficiently, equipment reliability improves and costly unplanned downtime is reduced.
If you are looking for further assistance to determine which maintenance approach makes sense for your plant Talk with an ATS expert to see which strategies are right for your facility.
Preventive vs predictive maintenance comparison
Feature | Preventive maintenance | Predictive maintenance |
Maintenance trigger | Scheduled intervals | Condition monitoring |
Data usage | Historical averages | Real-time equipment data |
Equipment downtime | Planned downtime | Minimal or targeted downtime |
Maintenance efficiency | Moderate | High |
Technology requirements | Low | Higher |
Choosing the right maintenance strategy for your facility
ATS can help your organization determine the best preventive or predictive maintenance strategies—or combination of the two—based on equipment reliability requirements, operating conditions and production goals.
ATS provides comprehensive maintenance solutions that are tailor-made for your specific organization to extend asset life and improve operational performance.
We can scale our services up or down to fit your needs as they change. Contact us today to find out how we can help.
