What Is Condition-Based Maintenance?

January 12, 2022

What Is Condition-Based Maintenance (CBM)?

Condition-based maintenance (CBM) involves monitoring equipment performance with visual inspections, scheduled tests, and sensor devices to determine the most cost-efficient time to perform maintenance. 

Summary

Condition-based maintenance is a management philosophy that bases the decision to repair or replace assets on current and/or future conditions. As Prabhakar, a research scholar at Karpagam University, mentions in this journal abstract

“[CBM] recognizes that change in condition and/or performance of an asset is the main reason for executing maintenance. Optimal time to perform maintenance is determined from actual monitoring of the asset, its subcomponent, or part. The objective of CBM is to minimize the total cost of inspection and repairs by collecting and interpreting intermittent or continuous data related to the operating condition of critical components of an asset.” 

Translation: Companies can act upon real-time indications of equipment depreciation, usage, and mishaps to avoid unnecessary downtime. Data used to inform CBM can stem from both continuous asset monitoring and predetermined intervals benchmarks. Regardless, the goal is the same:

Condition-based maintenance seeks to eliminate downtime, inform preventive maintenance tasks, and decrease unnecessary costs. Put simply, CBM decisions are based on current conditions so you are never overspending on preventive maintenance or reactive maintenance.  

Condition-Based Maintenance Workflow

CBM workflows range from simple to complex. However, most industries follow a similar model that emphasizes data collection, equipment forecasting, and corrective action. Of course, various levels of technological automation are available to organizations that can afford them. 

Here’s how condition-based maintenance works (most of the time): 

As illustrated, the active monitoring of an asset, part, or subcomponent determines the optimal time to perform maintenance. Equipment assessments may vary from simple visual inspections to elaborate automated ones utilizing condition monitoring tools and techniques. 

What Is the Difference between Condition-Based and Predictive Maintenance?

The terms condition-based maintenance and predictive maintenance (PdM) are often used interchangeably and for good reason. Both strategies encompass the same maintenance best practices: a) Rely upon data to determine whether or not upkeep is necessary and b) prevent unplanned downtime with proactive maintenance. However, that’s where the similarities end. 

Here are the differences between CBM and PdM:

Condition-Based MaintenancePredictive Maintenance
Relies on condition-based diagnostics (e.g. vibrations, temperature, pressure, speed, voltage) to indicate when maintenance is needed.Combines condition-based diagnostics (e.g. vibrations, temperature) with complex predictive formulas to predict when maintenance may be needed.
Relies on static rules for decision-making.Relies on dynamic rules for decision-making.
Very sensitive to noise input.Less sensitive to noise input.
Optimized form of preventive maintenance based on continuous detection, diagnostic, and prognostic algorithms to inform upkeep. Technologically advanced preventive maintenance based on algorithmic pattern recognition of machines. 
Alerts technicians at the exact moment when something is wrong. Predicts future failures with smart technology. 

Predictive maintenance is a more advanced, accurate, and dependable version of condition-based maintenance. However, the technology is so new that it’s not financially feasible for most organizations at this time. 

Examples of Condition-Based Maintenance

The examples below help explain CBM: 

Example 1: 

One common application of condition-based maintenance is the use of pressure readings on piping systems. Pressure levels are constantly monitored, allowing the maintenance staff to identify when possible leaks may occur. Manufacturers who rely on pipe or liquid systems, such as food and beverage producers, use CBM to track pressure and diagnose problems.

Example 2:

If you manage a fleet of vehicles, such as in the transport or construction industry, you may be used to scheduling an oil change based on a calendar schedule (such as every three months) or mileage (such as every 5,000 miles driven). But if you use CBM, your maintenance schedule may be informed by reading a gauge that monitors oil particles. This may mean changing the oil every 8,000 miles instead of 5,000 miles or after four months instead of three months. The advanced monitoring would save costs on engine oil.

Example 3:

Most buildings nowadays are upgrading to smart HVAC units that can provide real-time readings of temperature and humidity. This is a form of CBM that utilizes diagnostic algorithmic technology to adjust to control building temperature and alert management of any issues. This helps to prevent emergency shutdowns or worse, fire damage. 

Condition-Based Maintenance Monitoring Techniques

CBM technologies continuously collect data while equipment is in operation. These numbers are collected at given intervals and/or continuously through visual inspections, sensors, and scheduled tests. Processes for data collection can include:

  • Vibration Analysis: This type of condition-based monitoring system measures the vibration frequencies and levels of machinery. This information is then used by maintenance teams to analyze the health of equipment and their components to detect problems, such as bent shafts, resonance, looseness, bearing failure, and imbalance. For example, a damaged fan will produce more vibration signals.
  • Infrared Thermography: Infrared thermography is a condition-based monitoring system that uses thermal imagers to detect radiation from an object. The imagers convert the radiation to temperature and display its distribution in real-time. This helps in detecting when a piece of equipment is overheating.Examples of infrared tools include infrared thermal imaging cameras, infrared scanning systems, and infrared thermographers. They are mostly used to check the levels of gas, liquids, and sludge, inspect bearings; examine refractory insulation; and monitor the mechanical and electrical conditions of motors.
  • Ultrasonic Analysis: Ultrasonic analysis detects and converts high-frequency sounds into audio and digital data to help identify potentially failing assets. This type of condition-based monitoring system uses contact and non-contact methods of data collection to determine different types of detectable failure. Contact (structure-borne) methods are generally used for faults that generate high-frequency noise such as lubrication problems, bearing faults, broken rotor bars, and gear damage among others. Non-contact (airborne) methods, on the other hand, help in detecting pressure and vacuum leaks on compressed gas systems besides a variety of electrical applications.
  • Oil Analysis: Maintenance teams analyze oil health, contamination, and machine wear. They can determine whether the additives are active or depleted and whether the viscosity is right among other oil fluid properties. An oil analysis program will help to confirm if a piece of equipment is operating as it should.
  • Electrical Analysis: Here the focus is on the incoming power quality of assets. Circuit current is measured using motor current readings from clamp-on ammeters. Electrical analysis helps to determine if there is an abnormal amount of electricity supply to an asset.
  • Pressure Analysis: It’s important for pieces of equipment that carry air, gas, or fluid to maintain the correct amount of pressure. Maintenance teams use pressure analysis to continuously monitor pressure levels in real-time. They get alerts of sudden drops or spikes and can respond before it becomes more serious.

These six condition-based monitoring systems are the primary techniques used in CBM. Different companies use different systems based on their individual needs, budgets, and resources. Some companies, especially manufacturers, use more than one condition-based monitoring system.

Pros and Cons of CBM

Is CBM right for your company? Like every strategy, it has its advantages and disadvantages:

Pros of CBMCons of CBM
Improves lifespan of equipment, as maintenance is performed before equipment fails.Condition-based monitoring systems are expensive to install.
Reduces cost of equipment maintenance, as it is performed on a need basis.Significant investment is needed to train employees for chosen CBM technology.
Normal operations are barely disrupted, as CBM is performed while the asset is working.CBM systems barely detect fatigue failures.
Maintenance activities can be scheduled to reduce overtime costs. Repairs can be performed during non-peak times.Harsh working conditions, such as mines, can damage sensors.
Helps to maintain equipment performance at optimum levels.Difficult to predict when maintenance will be needed. May require using emergency budget.

In summary, the successful implementation of CBM can help companies significantly reduce maintenance costs in the long run. But the initial stages of implementation require high upfront costs that aren’t always achievable for small businesses that are still growing. If your company falls into this category, consider pursuing a planned maintenance strategy. Alternatively, CBM is best suited for large companies with vast resources.  However, different maintenance scenarios call for different maintenance strategies—even for large companies.

How to Implement Condition-Based Maintenance

Before launching a condition-based maintenance program, management must first link organizational needs to CBM software option capabilities. The last thing you want is to be part of the 80 percent of project management executives who have no idea how their projects align with their company’s business strategy. 

Questions for Choosing a CBM Solution

Here are questions to ask before implementing a CBM program:

  • Does it monitor specific failure modes? Failure modes refer to possible ways in which your assets could fail. Complex equipment usually has more than one failure mode. Choose a system that can identify these failure modes and improve asset reliability. Failure Modes and Effects and Criticality Analysis (FMECA) can help identify failure modes and their effects on the entire system for each asset.
  • Can you integrate the technology into your existing CMMS/ ERP systems? The cost of CBM technology is already high enough without adding the cost of completely overhauling your existing CMMS or ERP system. Make sure your current software systems are compatible with your CBM technology of choice. This will make it easier to train your team. Additionally, choose a CBM solution that ensures minimal disruptions to operations during installation. 
  • How easy is the program to implement? According to Guru99, ease of use is among the top requirements people look for when shopping for a new system. Some solutions are easier to implement and use than others. Choose an intuitively designed software option. 
  • Is the system scalable? Determine if the system can scale up over time as your company grows.

Understanding the P-F Interval and the P-F Curve

Your maintenance team can help to prevent asset failure if the signals can alert them to an impending failure. Luckily, machines give warnings beforehand. Your team can use the P-F curve to detect failures before they occur. The P-F Curve illustrates how a machine behaves as it approaches functional failure. Machines gradually deteriorate to a point where technicians can detect the deterioration (P).

At this point, failure begins to manifest, and if technicians do not mitigate the failure, the equipment continues to the point of functional failure (F). The time between point P and F is known as the P-F interval. It provides the perfect window for technicians to stop the equipment from breaking down completely, imminent failure.

In CBM, it is important to carry out effective analysis and perform maintenance during the P-F interval. Beyond that point, technicians will be undertaking reactive maintenance. To beat this, schedule inspections at the midway point of the P-F interval. The point of this is to have short monitoring times rather than having to save equipment during a tight P-F interval.

How to Establish a Condition-Based Maintenance Program

Establishing a CBM program doesn’t have to be difficult. Here’s how to develop your CBM program in six simple steps:  

  • Step 1: Select the equipment you want to monitor. Give priority to the equipment that is key to business success, high value, or has a longer lifespan.
  • Step 2: Identify the equipment’s failure modes. This includes all the known failure modes and probable ones. An RCM analysis can help with this. Always focus on the failure modes so that you can manage CBM strategies
  • Step 3: Select the right condition-based monitoring system. Ensure that the CBM system you choose can handle the failure modes identified in the previous step.
  • Step 4: Define your baseline limits for the system. For the system to warn you when the equipment is starting to fail, you have to define the acceptable condition limits. As indicated in the P-F Curve, ensure that the limits set give you enough time (P-F interval) to take corrective actions.
  • Step 5: Establish your CBM program. At this point, you should define tasks and assign responsibilities to your maintenance team. The focus should be on data collection and recording.
  • Step 6: Analyze the data and act as needed. The data from your inspections and sensors should help you plot trends and schedule maintenance work whenever necessary.

Condition-Based Maintenance Software Options

Several CBM software options are available in the market. Aim to choose software that can: 

  • Provide conclusive data in real-time. 
  • Provide notifications and work order triggers.
  • Generate reports that help identify trends and issues. 
  • Integrate with your CMMS to help automate schedules.

Is Condition-Based Maintenance Right for Your Facility?

As previously mentioned, the usefulness of CBM varies depending on organizational needs, budget size, and industry. Use the information outlined in this article as a starting point to investigate if a condition-based maintenance strategy will benefit your company. Additional tips on how to create a successful CBM program can be found here.

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