Criticality and reliability-centered maintenance go hand-in-hand. Think about it: We’re told to prioritize PMs for critical assets, to build a TPM plan that accommodates critical pieces of equipment, and to perform root cause analysis on machinery that we consider to be high priority based on criticality. But how do we actually decide what makes a piece of equipment “critical”? In short, it all comes down to risk. Performing a criticality analysis allows you to understand the potential risks that could impact your business.
What is criticality analysis?
Criticality analysis is a systematic approach to assigning a criticality rating to assets based on their potential risks. Still sounds kind of abstract, right? How can risk be quantified? It helps to think about criticality analysis as part of a larger failure modes, effects [and criticality] analysis (FMEA / FMECA).
As we’ve defined it recently, FMEA is an approach that identifies all possible ways that equipment can fail, and analyzes the effect those failures can have on the system as a whole. FMECA takes it a step further by conducting a risk assessment for each failure mode and then prioritizing what corrective actions should be taken.
Why is criticality analysis important?
As James Kovacevic of Eruditio describes, using a predetermined system to evaluate risk allows you to remove emotion from the equation. This ensures that reliability is truly approached from a risk-based point of view, rather than individual perception. Once equipment undergoes relative ranking based on its criticality, work can be properly prioritized and a condition monitoring strategy can be put in place. Performing an equipment criticality analysis also helps to clarify what can be done to reduce the risk associated with each asset.
Who’s responsible for criticality analysis?
So who actually carries out a criticality analysis? Industry experts say that it should be a cross-functional effort. We couldn’t agree more. It’s a much more effective process if input from operations, maintenance, engineering, materials management, and employee health and safety functions is considered. After all, risk can be defined differently for different teams. And since assigning risk will always be somewhat subjective, having a diverse background of knowledge to draw on will help to curb that.
How do you assess the criticality of an asset?
Asset criticality is the number value a business assigns to its assets based on their own set criteria. An asset criticality assessment can be done by creating a ranked list of work orders and orders in progress. This is known as an asset criticality ranking (ACR).
How to perform a criticality analysis
According to Kovacevic, there are two ways to carry out a criticality analysis. Both approaches produce a risk priority number (RPN) that allows you to rank the criticality level of each asset.
The first approach uses a criticality matrix, which is a 6×6 grid where severity of a given consequence (on the X axis) is plotted against the probability of that consequence occurring (Y axis). Naturally, if there is a high probability that a piece of equipment will fail in a way that causes great personal injury or severe operational issues, that piece of equipment is highly critical and should be prioritized accordingly. The number at the cross section of severity and priority for any piece of equipment is that piece of equipment RPN.
The second recommended approach is to separate the consequence categories by type (for example, health and safety, environmental, and operational). That way, you can rate how severe an equipment failure would be for each consequence category. For example, a piece of machinery that could cause severe personal injury upon asset failure would be a 5 or 6 in the health and safety category, but of almost no consequence to the environmental category (perhaps a 1 or 2), and moderately impactful to operations (somewhere in the middle). Once you’ve determined the severity of each consequence category for a given piece of equipment, you can multiply each of the categories together for that piece of equipment to get its RPN.
Once each piece of equipment has an RPN attached to it, you can rank them to assess which assets are critical. Kovacevic recommends grouping equipment into categories based on their RPN. Here are the categories he suggests:
Once each piece of equipment is ranked, maintenance managers can make decisions that are informed by risk, rather than gut feel. From here, all reliability-related activities and processes will run much more smoothly.
Every day, meat processing plants need to make sure the metal detectors in their machines are working. It’s a simple check to ensure there’s metal where there should be and no metal where there shouldn’t be.
This process involves running test balls through the machine. It takes about 45 minutes to complete (25 minutes of manual labour and 20 minutes of admin time). It’s routine maintenance— the type most people don’t give a second thought to.
It’s also an example of how tweaking maintenance processes can boost production efficiency. Instead of a manual check, the inspection can be done with an automated test-ball shooter. A button is pressed, the balls roll out on their own, and the task is wrapped up in five minutes. The result is more than 160 hours of extra equipment availability per year.
This is just one example of how companies can leverage maintenance to increase production efficiency. This article outlines several other strategies for bolstering production efficiency using maintenance, including:
How maintenance impacts production efficiency
Five ways the maintenance team can boost production capacity
How to measure the impact of maintenance on production
What is production efficiency?
Production efficiency is a measurement used mostly by manufacturers to determine how well (and how long) a company can keep up with demand. It compares current production rates to expected or standard production rates.
A higher rate of production efficiency delivers three critical outcomes for manufacturers:
Reduced resource usage: Efficient production systems produce the same number of goods with fewer resources
Higher financial margins: Efficient production means higher margins throughout the supply chain
A better customer experience: Efficient production allows products and services to be regularly and dependably delivered to customers
How to calculate production efficiency
The calculation for production efficiency compares the actual output rate to the standard output rate. The formula can be applied to either manual or automated work.
When it comes to industrial processes, the calculation takes quality into account. Let’s say you produce 50 units in an hour, but only 30 are useable. Your rate of production for that hour is 30 units.
The following formula is used to calculate production efficiency:
Production Efficiency = (Actual Output Rate / Standard Output Rate) x 100
For example, a manufacturing company receives a new order of 100 units. The standard rate of completion for 100 units is 10 hours, or 10 units per hour. However, the company took 12 hours to complete 100 quality units. In this case, the production efficiency formula would look like this:
Actual Output Rate = 100 units / 12 hours (8.3 units/hour)
Standard Output Rate = 100 units / 10 hours (10 units/hour)
Production Efficiency = (8.3 / 10) x 100 (83%)
In this instance, output and productivity levels are below capacity.
How maintenance can increase production efficiency
Proper equipment maintenance is essential for increasing production efficiency. It ensures your total effective equipment performance (TEEP) is as high as it can be. Using preventive maintenance to keep assets operating at their best helps to:
Limit equipment downtime: If equipment is checked regularly, you can find and fix failures before they cause big breakdowns that disrupt production. Having a solid preventive maintenance schedule also allows you to coordinate with production so planned downtime is done quickly.
Establish a corrective action system for failures: Having a strategy to find, analyze, and fix failure (aka a FRACAS) allows you to target recurring issues at their root. You can spot and eliminate problems that impact equipment availability and product quality the most.
Coordinate better shift changeovers: Better changeovers between maintenance shifts means communicating the right information to technicians quickly and accurately. This includes a run-down of what work needs to be done, when, and any obstacles that might get in the way of that work.
Ensuring standard operating procedures are clear and maintained: SOPs train operators to do routine maintenance so machines can be operated with fewer breakdowns and accidents.
Five things your maintenance team can start doing tomorrow to increase production efficiency
There are a lot of projects that take months or years to complete. But getting quick wins is also crucial for building momentum and proving the value of your maintenance team. So, here are five things your maintenance team can start doing tomorrow to increase production efficiency.
1. Optimize the frequency of your PMs
A preventive maintenance schedule can be a good example of having too much of a good thing. Going overboard on preventive maintenance can affect production efficiency in two ways. You can either waste valuable time preventing non-existent failure. Or you can increase the risk of failure by meddling with a perfectly fine component.
These guidelines can help you find the right balance between too many PMs and too few:
Use equipment maintenance logs to track the found failure rate on preventive maintenance tasks. Start with PMs that take the longest to do or cost the most.
If a PM leads to regular corrective maintenance, keep it at the same frequency.
If a PM rarely identifies failure, try increasing the time between inspections. If the found failure rate exceeds the frequency of the PM, tweak your schedule so it’s better aligned. For example, an inspection might happen every two weeks. But a failure is usually found every six weeks. In this case, plan for the PM to happen every 4-6 weeks instead.
If a machine experiences frequent breakdowns between inspections, try shortening maintenance intervals. You can also modify the trigger for maintenance, changing it from a time-based trigger to usage or performance-based trigger.
2. Identify machines that can be maintained while running
Some routine maintenance can be done while a machine is still operating. Find out if there are any assets that can be safely worked on while being used for production. The key word there is ‘safely’. This might mean that some work can’t be done because certain areas of a machine aren’t safely accessible while it’s operating. In this scenario, determine if partial maintenance is possible and if it’ll have a positive impact on the performance of the equipment.
It’s also a good idea to track rotating or spare assets and swap them for production equipment when possible. That allows you to do regular maintenance on these machines without sacrificing productivity.
3. Make equipment capabilities transparent and clear
Create an iron-clad list of instructions for operating equipment and common issues to be aware of. You can use a failure modes and effects analysis (FMEA) to create a list of common failures experienced by each asset. This can also include warning signs for breakdowns.
Having this information clearly outlined and easily accessible gives operators a chance to notice the early signs of failure and notify maintenance before it gets worse. Employees will be empowered to observe and identify any potential problems, and report them accordingly.
4. Use work order data to identify where your team can be more efficient
Work order data can tell you what jobs can get done quicker and how to minimize the risk of asset failure so you can boost production efficiency. Look for these telltale signs of broken processes in your work orders:
Unavailable parts and supplies: If this issue is delaying maintenance, review the purchasing process for parts and supplies. That includes making sure your cycle counts are accurate and the threshold for purchase approvals is low enough that inventory can get replenished quickly. You can also create parts kits for frequent repairs or emergency repairs on production equipment so your team can locate and retrieve parts quickly.
Misidentified/misdiagnosed problems or missing instructions: Make sure task lists, failure codes, and descriptions are clear. Attach photos, manuals, and other documentation to the work order.
Diverted resources resulting from emergency work orders: Emergencies can always be avoided. Analyze your work order data, find tasks that are too big, and break it down into smaller jobs to reduce the risk of major disruptions.
Scheduling conflicts with production: See if maintenance can be scheduled while production is happening or if work can be done at an alternate time, like evenings or weekends. You can also consider giving operators minor maintenance responsibilities associated with the work order.
Lack of adequate worker skillset: Work order data can show you if the person/people assigned to the work may not have the right skills. Make it very clear on the work request what kind of skills or certifications are necessary for certain maintenance types.
5. Find the biggest obstacles for your team and eliminate them
You can learn a lot from the data that comes from your equipment and work orders. But sometimes, you just have to ask the people who are doing the actual work. They will be able to tell you what barriers they face when completing work. Acting on this information is crucial to continually improve your maintenance processes. All those improvements can add up to a huge boost in production efficiency.
For example, your technicians may spend a lot of time going back and forth from the office to retrieve manuals, asset histories, or other materials that help them on a job. You probably won’t know that just by looking at work order records or wrench time reports. Armed with this information, you can figure out a solution. Maybe that’s creating areas throughout your facility where files can be accessed for nearby assets. Or it could be digitizing those files so they can be accessed through a mobile device.
Here are a few questions to ask your technicians to find any roadblocks:
What tasks commonly take you away from a machine?
Are information and parts easily accessible? If not, why?
What information would help you complete work more efficiently?
Are there processes or systems that are hard to use or you think could be improved?
Is there anything that frequently keeps you from starting a task on time?
Four ways to measure the impact of maintenance on production efficiency
There are many ways to measure how your maintenance efforts are affecting production efficiency. The most common metrics are the following:
Found failure rate on preventive maintenance
This metric will help you measure how efficient your preventive maintenance schedule is. If your found failure rate is high, it means you’re cutting down on unnecessary maintenance while preventing major disruptions to production.
Unplanned asset downtime (last 90 days)
This number tracks the amount of unplanned equipment downtime and compares it to the previous 90-day period. Because each minute of downtime lowers your production efficiency, this number highlights how maintenance is contributing to healthier, higher-performing assets.
Average time to respond to and repair breakdowns
This stat quantifies all the work you’ve done to prepare for emergencies. Breakdowns will happen. Having a plan to quickly and safely fix these failures will help you reduce the amount of time production is stalled.
Compare the amount of useable products coming from the equipment prior to and after maintenance is completed. If the machine is running better after maintenance, it’s proof that your team is increasing production capacity in a meaningful way.
Maintenance has the opportunity to drive production efficiency
Maintenance often gets talked about as an expense. A necessary evil. A cost-center. But the reality is, good maintenance can drive your business forward. When you keep the machines running, you can do more, faster, with less. That means happier customers, a better bottom line, and more profit for everyone in the supply chain. It’s a true win-win-win.
In order to turn maintenance from a cost centre to a business driver, you need to reorient maintenance as a business function and start asking how maintenance can drive production efficiency. From there, a world of opportunity opens up.
Maintenance analysis has changed a lot over the last decade or so. New tools and technology have increased our ability to collect and interpret data. It’s enabled us to make informed decisions that wouldn’t have been possible 10 years ago.
But if our understanding of maintenance analysis has changed, why do we still rely on the same handful of metrics we did 40 or 50 years ago?
Metrics like overall equipment effectiveness (OEE) and mean time to repair (MTTR) dominate almost every list of go-to industry measurements. But experts agree that they’re flawed. Not only are these traditional metrics prone to bias and inaccuracy, but they also often don’t have a purpose. And when data doesn’t have a purpose, you can’t use it to make key decisions, like whether to hire an extra technician or increase the frequency of a task.
That’s why we’ve put together 10 useful metrics you won’t see on any other list and some tips for how to use them to improve your maintenance program.
10 maintenance metrics for better maintenance analysis
#1 – Time spent supporting production
What is it?: The total time that the maintenance team spends on production-focused activities. Usually measured weekly, monthly, or quarterly.
How can you use it?: Everyone has to pitch in to complete a big order once in a while. But when once in a while turns into every day, maintenance suffers. This metric helps you catch an unhealthy backlog before it happens and reallocate resources to prevent it. It also helps you advocate for a higher headcount on your team or an increased training budget to help production staff learn minor maintenance tasks.
#2 – Follow-up work created after inspections
What is it?: The number of corrective work orders created from routine inspections. Usually measured monthly, quarterly, or annually.
How can you use it?: There are many different ways you can use this metric for maintenance analysis. You can sort it by machine, shift, or site to get insights into how your assets or team are performing. But the most useful is by task.
It’s a good sign when regular preventive maintenance includes follow-up repairs. It means your schedule is accurate and that you’re preventing bigger problems. It allows you to flag common repairs and build processes to make them more efficient. For example, you can create parts kits for quicker access.
If the failed inspection percentage is low, you can increase preventive maintenance intervals. This will reduce the amount of time and money spent on tasks without increasing risk.
#3 – Cost of follow-up maintenance vs expected cost of total failure
What is it?: A comparison between the cost of corrective maintenance (i.e. labor and parts) and the cost of asset failure if maintenance is not done (i.e. lost production, labor, and parts).
How can you use it?: Use this type of maintenance analysis to plan your maintenance strategy. For example, if regular inspections cost you more than failure, you can likely go with a run-to-failure approach for an asset over a preventive one.
You can also use this metric to prioritize tasks and backlog, and figure out how to allocate your budget.
#4 – Cost by maintenance type
What is it?: The total cost of maintenance (i.e. labor and parts) by maintenance type (ie. preventive, emergency, follow-up). Usually measured monthly, quarterly, and/or annually.
How can you use it?: Higher costs are usually the result of broken processes. This view allows you to find out which processes need work so you can increase efficiency.
For example, are work orders unclear and leading to increased repair times and labor costs? Try clarifying instructions.
Are you bringing outside contractors in to do emergency repairs? You could invest in more training for your team or hire a specialist.
#5 – Clean start-ups after maintenance
What is it?: The number of times a production line starts without stoppages or waste after completed maintenance. This is measured monthly, quarterly, and annually.
How can you use it?: Include this metric in your maintenance analysis to draw a direct line between your team’s work and increased output.
If clean start-ups are low, it gives you another chance to spot problems in your processes. For example, you might find that the specs for a production line may be out of date. This will lead technicians to rebuild components incorrectly and the line to stall. Updating the specs is a simple tweak that could lead to higher output.
#6 – Size of backlog
What is it?: The total number of hours of overdue and scheduled maintenance tasks. Track this metric weekly and monthly.
How can you use it?: This metric can be a godsend when it comes to getting your team some much-needed relief. Quantify the gap between available labor hours and your total backlog hours. You might find that the amount of backlog far outpaces how much your team can do. Use that to make a case for more budget to spend on extra overtime, hiring another technician, or bringing in more contractors.
#7 – Top 10 assets by downtime
What is it?: This is your heavy hitters list—the equipment that breaks down most often or takes the longest to repair. Keep tabs on these assets weekly, monthly, and quarterly.
How can you use it?: This metric keeps your biggest problems visible. You might raise an eyebrow at that, but highly visible problems get solved the fastest. This kind of maintenance analysis can help you prioritize your problem-solving efforts, make decisions quickly, and measure their impact.
For example, if you know asset A is at the top of your downtime list, you can start by isolating the reason why. Is it because repairs take longer on that asset? Is work being delayed? Does that piece of equipment break down again and again?
The answer to these questions will give you an idea of how to prevent failure in the future. You might get rid of obsolete parts that keep breaking. Or put an extra technician on a job. Or clarify how much lubrication should be used on a bearing. If all else fails, conducting this type of maintenance analysis helps justify a capital expenditure on new equipment.
What is it?: The ratio of planned maintenance to all other types of maintenance over the last 90 days.
How can you use it?: This is a measure of progress. Going from reactive to planned maintenance doesn’t happen overnight. The time frame allows you to make a clear connection between action and results. You can draw a line between what happened and its impact on your end goals.
For example, if your percentage has dropped, you can look at what happened in the last 90 days to cause that drop. That could be a massive, unexpected breakdown. Or an increase in production support during the busy season. If you want to increase the percentage, try creating a better work request process to uncover problems earlier. Or shorten inspection intervals on assets with the highest instances of unexpected downtime.
#9 – Wrench time (last 90 days)
What is it?: The amount of time technicians spend working on a piece of equipment as part of the total time it takes to complete a job. This is usually measured by job or as a weekly, monthly, and quarterly average.
How can you use it?: Wrench time is a common tool for maintenance analysis, but it’s often used the wrong way. Technicians usually (and unfairly) get the blame for low-wrench time. It leads to wrench time inflation as technicians fudge the numbers to avoid trouble.
Low wrench time usually has its roots in broken processes, not the ability of the technician. That leads to bigger backlogs, more reactive maintenance, and avoidable labor costs.
To use wrench time in your maintenance analysis, start with the jobs that have the lowest scores. Review these jobs step-by-step with technicians. Work together to find out where unclear or incomplete processes cause delays. You’ll spot bottlenecks easier when breaking the task down into smaller pieces. The result is more value for your team’s time and money.
#10 – Health and safety work orders completed
What is it?: The number of work orders completed for health and safety or compliance purposes. This is usually tracked monthly, quarterly, and annually.
How can you use it?: Some metrics are quantitative. Others are qualitative. This one is the latter. And it’s essential for measuring the performance of your maintenance team and the impact it has on your business. A safe workplace keeps accidents low, and productivity and morale high. Passing audits and remaining compliant is crucial to staff safety and avoiding fines.
Three big goals you can accomplish by combining these metrics
All the metrics mentioned above are powerful in their own right. But when combined, they supercharge your maintenance analysis and help you achieve three common goals:
Get a bigger budget and more time for maintenance
Metrics to combine:
Cost by maintenance type
Clean start-ups after maintenance
Top 10 assets by downtime
Getting more money and time for maintenance means winning over whoever divvies up the budget, and whoever leads production. The quickest way to get them on board is to align your plan with their goals. The three metrics above will help you get there.
First, highlight the cost-benefit of preventive maintenance. Regular preventive maintenance might seem expensive. But just one instance of emergency maintenance can cost up to $250,000. If you’re tracking cost by maintenance type, you can highlight how much the company is losing with reactive maintenance, and how much it can save you by investing in preventive maintenance.
Next, it’s time to sway the production team. Use clean start-ups after maintenance to show production that you have their best interests in mind. It emphasizes what is good for maintenance is often good for production.
No one is going to give you more resources without a plan. Your list of bad actors is a blueprint for how you’re going to make the most of your extra time and money. It quantifies the problem and makes it very clear where you’ll focus your efforts.
Get your maintenance team to buy into change
Metrics to combine:
Planned maintenance percentage (90 days)
Wrench time (last 90 days)
Follow-up work created after inspections
Change sucks. And that makes it hard for your team to get on board with a new system or process. The best way to change the mind of naysayers is to show them how your plan is eliminating their biggest pains. Tracking the metrics above is one way to do this.
These data points give you a chance to compare how you operated before a change (i.e. lots of reactive maintenance and frustration over guesswork) and what you’ve accomplished since implementing a new system or process. Seeing the pay-off first-hand makes it easier to convert any critics and expand your project, whether it’s setting up a CMMS or allowing machine operators to do routine maintenance.
Build a preventive maintenance program that would make most other companies jealous
Metrics to combine:
Cost by maintenance type
Follow-up work created after inspections
Cost of follow-up maintenance vs expected cost of total failure
The best preventive maintenance programs don’t have the most PMs. Instead, they have the most efficient PMs. That means doing the right work at the right time. These metrics will help you achieve this balance.
Measuring cost by maintenance type helps you allocate resources to preventive tasks and gauge the efficiency of your PMs. You can track if cost-cutting strategies are working and make sure they’re not leading to reactive costs down the line.
Keeping tabs on follow-up work is one way to optimize PM frequencies. If an inspection isn’t leading to corrective work, you can increase inspection intervals. That means you can use fewer labor hours and parts, and spend that money and time elsewhere. Similarly, comparing the costs of corrective maintenance and total failure ensures you’re not spending money on proactive tasks that aren’t worth it.
The best maintenance analysis is constantly evolving
The best maintenance metrics have a purpose. They are collected and used consistently. They guide decisions and inform you on how to run your maintenance program on a daily basis. This is the backbone of successful maintenance analysis.
On the flip side, all maintenance analysis is a work in progress. Revisit your metrics on a regular basis to make sure they’re still relevant to your goals and the way your maintenance team works. Some of the metrics listed above might work for you now, but you might find others are more effective in six months. Or maybe five years.
Lastly, the best maintenance analysis incorporates data that other departments find useful. If you can connect the metrics above to solve the challenges of other business units, you’ll be well on your way to creating a world-class maintenance program.