Predictive Maintenance VS Preventive Maintenance

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Organizations lose thousands of dollars in revenue for every minute their equipment is down—whether in a manufacturing facility, managing a large vehicle fleet, or maintaining critical infrastructure. The maintenance strategy you choose plays a crucial role in determining your operational efficiency.

In this discussion, we'll explore three maintenance strategies that are now widely used in the industrial sector: reactive maintenance, predictive maintenance, and preventive maintenance. While all these approaches aim to reduce the risk of equipment failure, they differ in how they tackle the problem, the costs involved in implementation, and their effectiveness in minimizing downtime. Understanding these distinctions is vital, as making the right choice can help your organization save both time and money.

Preventive Maintenance: The Scheduled Approach

Preventive maintenance is a method in which service is performed on equipment at a schedule, regardless of condition. Preventive maintenance, like changing the oil in your car every 3,000 miles or replacing air filters every 6 months, is based on a calendar and not based on issues.

Preventive maintenance involves conducting scheduled maintenance on equipment and machinery before unexpected failures occur. Instead of waiting for breakdowns, the goal of preventive maintenance is to reduce unplanned downtime by proactively identifying and addressing potential issues through a structured maintenance program.

By performing regular maintenance tasks at predefined intervals, preventive maintenance helps lower the chances of equipment failure, ensuring that assets continue to operate smoothly.

Three primary types of preventive maintenance have emerged, each involving repeatable maintenance procedures, but with varying schedules and tailored to different operational needs within a business.

  • Usage-based preventive maintenance schedules trigger maintenance or inspections based on the usage of an asset, like replacing your car tires after driving 50,000 miles.

  • Calendar or time-based preventive maintenance follows fixed intervals, such as servicing your home furnace annually.

  • Condition-based maintenance is determined by monitoring the asset’s wear and degradation over time.

Characteristics of Preventive Maintenance:

Scheduled Intervals: Maintenance tasks are planned for a specific time, or planned for a specific number of hours, or based on a specific number of miles or miles. It is not dependent on the true condition of the equipment.

Proactive Approach: Instead of waiting for equipment to break down, maintenance is performed before problems arise.

Focus on Equipment Lifespan: The focus is to see the equipment actions are happening at that level and hopefully extend the lifetime of the equipment by keeping on top of wear and tear.

Standardization: Procedures are usually standardized for the same type of asset or same model of asset

				
					Example: A factory might have a preventive maintenance schedule that requires the replacement of filters every six months or a quarterly inspection of machinery to ensure its parts are not worn out.
				
			
Image Example Preventive Maintenance

Challenges of Preventive Maintenance

Despite its many benefits, organizations often encounter challenges when implementing preventive maintenance:

Over-Maintenance Issues

Strict adherence to scheduled maintenance can lead to resource wastage by maintaining equipment unnecessarily. Replacing parts based on fixed time intervals, rather than their actual condition, often results in premature replacement of components that still have useful life left.

Scheduled maintenance can be costly; taking equipment offline for routine servicing requires valuable staff time, even when the equipment is functioning well. This approach overlooks the actual condition of the equipment.

Scheduling Conflicts

Scheduled maintenance shutdowns can impact production as the shutdown may interfere with peak production times or critical deadlines. Also, when several pieces of equipment are scheduled for maintenance at the same time, there is a strain on maintenance personnel along with production bottlenecks.

Scheduled
or planned maintenance based on fixed timeframes also restricts the maintenance personnel from making flexible plans according to the operational needs or seasonality of how the equipment is used.

Hidden Failures

Routine maintenance can create a false sense of security, potentially overlooking issues that develop between scheduled appointments. Common maintenance practices may also miss certain failure modes, particularly those that progress quickly.

Furthermore, traditional maintenance often focuses on individual components rather than the entire system, which may result in problems going unnoticed.

Documentation and Compliance Burden

Documenting detailed information for all scheduled maintenance events can be a burdensome administrative task, leading to an overload of paperwork. Additionally, varying regulations may require different maintenance frequencies, making scheduling more complex.

Other challenges include proving compliance, verifying the effectiveness of maintenance programs, and managing record-keeping. Moreover, ensuring everything is properly audited can be a significant issue.

Predictive Maintenance: The Data-Driven Approach

Predictive maintenance adopts a data-driven approach, utilizing real-time monitoring and analytics to forecast when equipment is likely to fail. Instead of relying on fixed schedules, maintenance is performed only when data shows that equipment performance is deteriorating or failure is imminent.

By leveraging data analytics, sensor technology, and condition-based monitoring techniques, predictive maintenance can foresee potential failures before they occur. Unlike preventive maintenance, which follows a set schedule, predictive maintenance is driven by real-time data from equipment, allowing organizations to base decisions on the actual health of their assets.

Various condition monitoring techniques are used to detect anomalies and provide early warnings of potential issues. These include sound (ultrasonic acoustics), temperature (thermal), lubrication (oil and fluid analysis), vibration analysis, and motor circuit diagnostics.

For instance, a rise in temperature in a component could signal an airflow issue or coolant blockage, while unusual vibrations may indicate misaligned or worn-out parts. A change in sound can provide an early warning of faults that are undetectable by the human ear.

The oil & gas sector was an early adopter of predictive maintenance, mainly to reduce the risk of environmental disasters. Now, other industries are seeing the benefits as well. For example, in the food and beverage industry, undetected food storage faults can lead to severe health risks, while shipping companies can prevent equipment malfunctions, knowing repairs are more cost-effective when made in port than at sea.

Characteristics of Predictive Maintenance:

Condition-Based: Maintenance tasks are triggered by real-time data, indicating that a specific part of the equipment is showing signs of wear or potential failure.

Advanced Technologies: This approach leverages key technologies such as sensors, IoT devices, machine learning, and AI to continuously monitor the health of the equipment.

More Accurate Interventions: Maintenance is performed only when necessary, based on insights from ongoing monitoring, thereby reducing unnecessary downtime.

Cost-Effectiveness: By addressing issues before they lead to failures, proactive maintenance helps avoid costly repairs and unexpected downtime.

				
					Example: A company might use IoT sensors to monitor vibration and temperature in a motor. If the data shows unusual patterns or exceeds predefined thresholds, a maintenance request is triggered, preventing a potential failure before it happens.
				
			
Image Example Predictive Maintenance

Challenges of Predictive Maintenance

While predictive maintenance offers numerous benefits, it also presents its own set of implementation and operational challenges:

High Initial Investment

Implementing a predictive maintenance program comes with significant costs. Developing and deploying such a program involves expenses for sensors, monitoring technologies, analytical software, and more.

In addition, enabling technologies may require upgrades to IT infrastructure, networking capabilities, and data storage systems. Staff will also need training to interpret data, optimize the use of new technologies, and ensure that condition-based maintenance decisions are based on thorough and accurate analysis. All of these factors contribute to the substantial investment needed for a successful predictive maintenance program.

Technical Complexity

Combining all the necessary data in predictive maintenance can be a technical challenge, requiring many times the need for specialist expertise due to this data coming from sensor, systems, and other sources, develop accurate predictive model that uses advanced analytics, and maintain the accuracy of the models over time and as the analytics advance.

Pertaining
to reliability of the system as a whole, reliability of data is often overlooked or given less attention, because a system could be producing accurate predictive analytics based on an incorrect sensor or erroneous data communication relating to that data.

Data Quality Issues

Sensor accuracy is crucial, particularly in predictive maintenance. Faulty or poorly calibrated sensors can produce unreliable data, leading to incorrect maintenance decisions. Even data from a small number of sensors can quickly become overwhelming, making it harder to identify real trends and patterns.

Additionally, an overly sensitive monitoring system can trigger false alarms, leading to unnecessary maintenance actions and ultimately diminishing confidence in the system’s reliability and effectiveness.

Skill Requirements

The success of predictive maintenance depends on personnel capable of working in specialized areas such as data analysis, vibration analysis, thermography, and other forms of diagnostic thinking. The job market can be challenging due to a lack of personnel with that skill level, and employing such programs can make things even more difficult.

As
technology is moving quickly, maintenance teams must learn continuously, and find ways to develop their skills, in order to adapt to new tools and technology, and to make predictive maintenance successful over time.

Key Differences Between Preventive and Predictive Maintenance

Aspect
Preventive Maintenance (PM)
Predictive Maintenance (PdM)
Approach

Scheduled based on time or usage intervals

Data-driven, based on actual asset conditions

Cost Considerations

Lower initial investment in technology and training

Higher upfront investment in sensors, software, and training

Maintenance Frequency

Regular intervals regardless of asset condition

Performed only when necessary, based on data

Implementation Complexity

Relatively simple to implement and manage

More complex implementation requiring specialized technology

Risk of Failure

Risk of unnecessary maintenance or missed issues

Minimizes risk of unplanned breakdowns

Operational Impact

Can lead to unnecessary downtime and resource allocation

Reduced downtime with more efficient resource usage

Resource Utilization

Requires maintaining large inventories of spare parts

Reduces spare parts inventory through better demand forecasting

When to Choose Preventive Maintenance

Preventive maintenance is ideal for:

Critical safety equipment – Where equipment failure could have a serious safety, financial, or environmental impact, following a scheduled preventive maintenance is a more effective way to ensure safety standards are met.

Low-cost equipment – For equipment that is inexpensive, the cost of setting up monitoring technology may be greater than the value of the equipment.

Simple systems – Where the maintenance procedures are simple enough that implementing a complex condition monitoring system does not make good economic sense.

Regulated industries – Many industries and sectors have compliance requirements that mandate a defined maintenance schedule and procedure.

Limited technical resources – Where the organization may not have significant technical skill or capacity to be implementing predictive maintenance.

Industries that benefit from preventive maintenance:

  • Food and beverage

  • Healthcare facilities 

  • Transportation (due to compliance and safety of safety-critical systems)

  • Small manufacturing operations

  • Facilities management

When to Choose Predictive Maintenance

Predictive maintenance is most effective for:

High Value Equipment – Costly machinery where the impact of an unintended failure is high.

Critical Production Equipment – Machinery that would cause significant delays if it failed.

Complex Systems – Equipment with several failure modes that needs to be monitored routinely.

Variable Operating Condition – Equipment that operates with variable loads, temperatures, and any other harsh physical conditions.

Experienced Technical Teams – Organizations with knowledgeable technicians that can interpret the data and make informed decisions.

Industries that benefit from predictive maintenance:

  • Oil and gas production

  • Power generation

  • Chemical processing

  • Heavy manufacturing

  • Data centers

The Importance of Data Management in Contemporary Maintenance Practices

Regardless of which maintenance approach you choose, effective data management is crucial for success. Poor data quality can lead to:

  • Incorrect maintenance decisions

  • Missed maintenance opportunities

  • Duplicate work orders

  • Inaccurate equipment histories

  • Compliance issues

Future Trends in Maintenance Management

The maintenance landscape keeps changing as technology develops further:

Artificial Intelligence: We are seeing more advanced AI algorithms which are better equipped to predict equipment failures along with empowering us to improve our schedule and methodologies for maintenance.

Internet of Things (IoT): More sensors or connected devices create improved data for decision-making in a maintenance sense.

Augmented Reality: AR technology helps technicians see a visualization of equipment problems and procedures in following maintenance.

Digital Twins: Systems which operate in a virtual clone of the original system; they build simulations and predictive models.

Cloud Computing: Meaning I can now access maintenance management systems that are based in the cloud, which affords tremendous scalability on a cloud service, and the possibilities are opening for organizations of every size.

Conclusion

It is up to the organizations these days to determine the best predictive and preventive maintenance method to use; both methods (predictive and preventive) have benefits. Preventive maintenance is simple, often predictable, and a relatively low initial investment, which is the case in many organizations and many types of equipment. Predictive maintenance looks for optimization, efficiency, and cost savings of the entire process, especially in areas where there is criticality and expensive equipment.

For
many of these organizations who have been successful, the model is hybrid. They have preventive maintenance as the base, and apply predictive maintenance on a limited basis, to their most critical assets. The organizations get the reliability from a scheduled maintenance program, while simultaneously getting the efficiency in terms of workload from a conditioned-based maintenance (predictive) program.

While
it does not matter if you use a preventive, predictive, or hybridized maintenance strategy, you have to understand this first and foremost. Clean and accurate data and good data management practices are the foundation for success. If you do not have trusted data, then no maintenance strategy no matter how sophisticated will have credibility.

With
an advancing and more cost effective technologies, predictive maintenance strategies will get closer to being what is currently known as standards on more types of equipment and more types of industries. However, preventive maintenance strategies will still be applicable in a wide variety of possible application scenarios: based on simplicity, compliance or cost for example.

The key is to start with a clear understanding of your organization’s needs, capabilities, and constraints, then choose the maintenance strategy that best aligns with your operational goals and available resources. With the right approach, you can minimize downtime, reduce costs, and maximize the value of your equipment investments.

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