Skip to main content

5 Important Maintenance Metrics and How To Use Them

By Bryan Christiansen, Limble CMMS.

Source: maintworld.com

Effective maintenance of equipment is a critical factor in delivering quality operations that provide timely resources at a minimal cost. However, those in the maintenance field understand that equipment reliability does not come easy. 

Organizations need to set quality benchmarks to measure the current effectiveness and predict future performance and use the data obtained to understand where to make improvements.  

One way to do this is by using different maintenance metrics to understand the equipment performance. These metrics are very important as they can mean the difference between achieving the overall business goals and explaining how unexpected breakdowns caused yet another production delay.  

Maintenance Metrics You Should Be Measuring

What are the maintenance metrics?

There are two categories of maintenance key performance indicators which include the leading and lagging indicators. The leading indicators signal future events and the lagging indicators follow the past events. 

The leading indicator comprises metrics like the Estimated vs actual performance and PM Compliance, while the lagging indicator is reflected in maintenance metrics like the Mean Time To Repair (MTTR), Overall Equipment Effectiveness OEE and Mean time between failure (MTBF). 

Using these maintenance metrics and turning the data into actionable information, organizations can acquire both qualitative and quantitative insights. 

And there is no better way to spot opportunities for improvement.

Here are some important maintenance metrics you should track if you want to improve and optimize your maintenance operations.

1. Planned maintenance percentage (PPC)

This metric represents the percentage of time spent on planned maintenance activities against the unplanned. 

In simpler terms, this metric tells you how much maintenance work done on a particular asset was a part of your preventive maintenance plan versus how much time you’ve spent repairing it because it unexpectedly broke down.

In a great system, 90% of the maintenance should be planned. 

The calculation is as follows:

PPC= (scheduled maintenance time/total maintenance hours) x 100

2. Overall Equipment Effectiveness (OEE)
OEE is the measure of the productivity of a piece of equipment. It gives informed data on how effective an organization’s maintenance processes are running based on factors like equipment quality, performance, and availability. 

A 100% OEE means that your system is producing no defects, as fast as possible, and with no stops in the production.

understanding OEE and the underlying losses, organizations can gain significant insights into how to improve their manufacturing processes. Using this metric, you can identify what has a negative impact on your production, so you can eliminate it.

To calculate the OEE, you multiply the availability by the performance and quality :

OEE = availability x performance x quality

3. Mean time to repair (MTTR)

MTTR is the measure of the repairable items' maintainability. 

The MTTR clock starts ticking when the repairs start and it goes on until operations are restored. This includes repair time, testing period, and return to the normal operating condition.

The goal of every organization is to reduce MTTR as much as possible. This is especially important for critical assets as every additional hour you need to restore an asset to a working condition amount to huge losses for your firm.

To calculate MTTR, you divide the downtime period by the total number of downtimes:

MTTR= (SUM of downtime periods/ total number of repairs)

4. Mean time between failure (MTBF)

MTBF is the measure of the predicted time between one breakdown to the next during normal operation. 

In essence, MTBF tells you the expected lifetime for a specific piece of equipment. Higher MTBF means that the part (or product) you bought will work longer before it experiences failure.

If you know how long a specific part/equipment will last, it gets much easier to predict and prepare for a failure or schedule some preventive work.

To calculate the MTBF, you divide the total operational time by the number of failures:

MTBF= (SUM of operational time/total number of failures)

5. Preventive maintenance compliance (PMC)

PM compliance is defined as the percentage of the preventive work scheduled and completed in a set time.  

For example, you might have 60 Work Orders (that are a part of the PM plan) scheduled but 51 completed at the end of the month.

In this case:

PMC= (51/60) x 100 = 85%

This tells you that 85% of all preventive WO’s have been covered for selected month.

The disadvantage of this metric is that it doesn’t tell you if the WO’s have been completed on time. 

That is why you need to invest some additional effort and also track if the Work Orders are actually being finished on time. 

By far the best way to do that is to use a CMMS as it allows you to quickly create, assign, and track all of your WO’s from one place.

 Conclusion

The best way to track if your actions have a positive impact on your maintenance operations is to accurately track metrics that can show you if you are going in the right direction.

Improvements based on your “feeling” can never be as good as relying on hard data.

 

Bryan Christiansen is the founder and CEO of Limble CMMS. Limble is a modern, easy-to-use mobile CMMS software that takes the stress and chaos out of maintenance by helping managers organize, automate, and streamline their maintenance operations.

 

Labels:

Comments

Post a Comment

Popular posts from this blog

John Crane's Type 28 Dry Gas Seals: How Does It Work?

How Does It Work? Highest Pressure Non-Contacting, Dry-Running Gas Seal Type 28 compressor dry-running gas seals have been the industry standard since the early 1980s for gas-handling turbomachinery. Supported by John Crane's patented design features, these seals are non-contacting in operation. During dynamic operation, the mating ring/seat and primary ring/face maintain a sealing gap of approximately 0.0002 in./5 microns, thereby eliminating wear. These seals eliminate seal oil contamination and reduce maintenance costs and downtime. John Crane's highly engineered Type 28 series gas seals incorporate patented spiral-groove technology, which provides the most efficient method for lifting and maintaining separation of seal faces during dynamic operation. Grooves on one side of the seal face direct gas inward toward a non-grooved portion of the face. The gas flowing across the face generates a pressure that maintains a minute gap between the faces, optimizing flui...
Post a Comment
[Read more...]

Top 8 Reasons for Mechanical Seal Failure and How to Prevent Them

Mechanical seals are critical components of pumps, responsible for maintaining a fluid-tight seal between the rotating shaft and the stationary pump housing. However, these seals can fail due to various factors, leading to leakage, reduced pump efficiency, and costly downtime. In this article, we will discuss the top reasons for mechanical seal failure in pumps and how to prevent them. 1-Improper Seal Selection Choosing the wrong mechanical seal can cause it to fail. Consider the following factors that can contribute to seal failure: • Chemical compatibility: All seal components, such as the seal faces and O-rings, must be compatible not only with the process fluid being pumped, but also with non-process fluids used for cleaning, steam, acid, and caustic flushes, etc. • Physical degradation: Using soft seal faces on abrasive liquids will not last. Shear-sensitive liquids, like chocolate, can break down and leave behind solids (such as cocoa powder) and force out liquids (like oil). • S...
Post a Comment
[Read more...]

Why Pump Shafts Often Break at the Keyway Area

By NTS Pump shaft failure can lead to significant downtime and repair costs in industrial plants. One of the most common locations for pump shaft failure is at the keyway area. In this article, we will explore the reasons why pump shafts often break at the keyway and what can be done to prevent such failures. The keyway is a high-stress point (weakest point)  on the shaft, where a key is inserted to transmit torque between the shaft and the pump impeller or coupling. During operation, the keyway experiences cyclic loading that creates a bending moment in the shaft, which is concentrated in the keyway area. Over time, this cyclic loading can cause fatigue failure in the shaft material, leading to a fracture at the keyway. In addition to cyclic loading, other factors can contribute to shaft failure at the keyway. Improper keyway design or installation can lead to stress concentrations or inadequate clearance between the key and keyway . Misalignment or overloading can also cause ex...
Post a Comment
[Read more...]

Grounding brush discharge monitoring

In recognition of the possibility of static charge build up in condensing steam turbines, API 612 (2005) specifies that grounding brushes be installed. The electrical flow to ground through these brushes  be monitored and useful information can be extracted. This article carries excerpts from the paper, “Babbitted bearing health assessment” by John K Whalen of John Crane, Thomas D Hess of Chestnut Run, Jim Allen of Nova Chemicals and Jack Craighton of Schneider Electric. Grounding brushes take current from the rotor to ground so that a charge does not build up on the rotor to the point where it discharges to ground though the best path possible – which is usually the closest point between the rotor and stator which is usually (hopefully) the point of minimum film thickness in a bearing. Typically this point of minimum film thickness is found in the active thrust bearing (as will be shown later). Shaft grounding brushes serve two purposes. The brushes are able to transmit modest amo...
Post a Comment
[Read more...]

Thermal growth: how to identify, quantify and deal with its effects on turbomachinery

Thermal growth, as used in the field of machinery alignment, is machine frame expansion resulting from heat generation. The generation of heat, of course, is caused by operational processes and forces. Materials subjected to temperature changes from heat generation will expand by precise amounts defined by their material properties. In turbomachinery, thermal growth results from the temperature differences occurring between the at-rest and running conditions. Generally speaking, the greater the temperature difference, the greater the thermal growth. The magnitude of the growth can be calculated from three variables: ∆ T (temperature difference) C   (coefficient of thermal expansion) L    (distance between shaft centerline and machine supports) When machinery begins to generate heat, the temperature difference between at-rest and running conditions will cause thermal expansion of the machine frame, thereby bringing about the movement of the shaft centerlines. This can...
Post a Comment
[Read more...]