Table of contents
What Is Equipment Reliability?
Equipment reliability is the predicted measure of time that a piece of equipment will correctly function. The reliability of equipment is measured based on the time the equipment runs without failure.
If a piece of equipment is meant to last 9,000 hours (approximately 12 months) of continuous operation, the machine must run correctly for a minimum 9,000 hours if it is to be regarded as 100% reliable. If it runs for less than this time, the reliability score will suffer. If it continues running after this time but with the occasional failure, the reliability score will be moderated accordingly.
If you are running a tight ship organization, equipment failure can result in unplanned downtime that interferes with your schedule. Understanding machine reliability can help you improve the efficiency of your operation.
Why Is ERM Important?
Equipment reliability and maintenance (ERM) is directly linked to three important elements of competitiveness – cost, quality, and production lead time. Reliable machines work more effectively which leads to consistently higher-quality products. ERM also reduces production costs by increasing uptime and decreasing the need for spare parts and retooling.
Repair time often exhausts both funds and employees. By integrating a system to enhance ERM, the average time between equipment failure can be significantly increased.
The Strategy For Higher Reliability
Improving ERM requires investing in a long-term maintenance strategy. This strategy works to maximize the time between failures by taking actionable steps to reduce the risks associated with failure. This involves ensuring the local operating conditions are optimized and that the parts and components of the machine operate with low-stress. If you can reduce external factors that cause failure, you can increase the time your equipment operates at full capacity.
Ways To Improve ERM
Ultimately, the important question is how you can make positive changes in your maintenance organization to improve reliability. We have listed some of the key actions you can take below.
Use Data To Drive Business Decisions
The best maintenance practices use data to drive business decisions. Root cause analysis, for example, enables you to identify why a machine failed and prevent the failure from reoccurring in the future. In addition to root cause analysis, data that indicates the time spent on repairs, how downtime has impacted product losses, and how the machine’s reliability compares to other equipment, can all help you determine what actions to take.
Work With Precision
Precision maintenance has a direct impact on reliability. Assembling equipment with the proper tools and hardware improves performance and reduces the risk of reliability issues. Comparatively, equipment that is assembled using precision tools experiences fewer failures than equipment where precision tools were not yet.
Accurately Record Maintenance History
It is the responsibility of your maintenance technicians to accurately record maintenance history. Accurately recording failure history not only allows you to implement efficient failure modes, but it also allows you to identify the areas you can improve if you want to impact plant reliability.
Understand Your Employee’s Limitations
Often, managers overestimate the maturity of the company’s reliability effort. It is important that you properly assess your employees so you can be sure they understand what proper maintenance planning entails. You can do this with a simple internal self-assessment. If there are employees who are not up to scratch on their knowledge of failure mechanisms and maintenance planning, it is your job as a managing director to ensure they receive proper training.
Work Closely With Maintenance Technicians
Your reliability engineers should work closely with maintenance technicians to resolve rotating equipment issues. It is the job of operations managers to ensure that the technicians are using proper precision techniques and are familiar with the core performance indicators. This involves demonstrating the difference between a precision-aligned asset and one that has not been aligned. Helping your maintenance technicians understand the importance of reliability will make a difference in how they perform routine maintenance.
Measurements To Track ERM Performance
Measuring and monitoring the activities of each department is essential for managers if they want to understand how each component of the operation affects the company’s performance.
The most commonly used measurements managers use to determine performance are: mean time to repair (MTTR), mean time between failure (MTBF), and availability.
These measurements are all crucial components of the reliability of equipment. This means that each measurement has an impact on the cost-efficiency of the company.
MTTR is the measure of the department’s ability to perform maintenance that restores equipment to the desired condition. This measurement is expressed in hours and is calculated by the total repair time spent on a machine divided by the number of times repairs have been needed.
When calculating MTTR, it is important to clarify whether the R stands for repair, respond, recovery, or resolve. Although these terms are similar, it is important that everyone is in agreement about what specifically is being measured.
How to calculate MTTR?
To calculate MTTR, add up the total time spent on repairs for a specific machine. This includes every minute spent on repairs before the machine is fully functioning.
Next, divide the total time spent on repairs by the number of repairs that have been carried out. For example, if a machine malfunctions five times in a month and 500 minutes are spent on repair, the MTTR is 100 minutes.
The MTBF is the average time between repairable failures of a piece of equipment. The more reliable a system is, the more time will pass between failures.
Obviously, the aim is to keep the MTBF as high as possible. The more hours you can put between issues, the more uptime you can exploit.
How to calculate MTBF?
To calculate MTBF, you must first define the period of time you want to calculate i.e. six months or a year etc. You then divide the operational time of that period by the total number of failures. MTBF does not factor in scheduled maintenance, only unpredicted issues.
For example, if a machine breaks down five times over five months, the MTBF is one month.
In reliability engineering, the term “availability” usually refers to one of two things:
- The degree to which a system or piece of equipment is in a specified operable condition at the start of an operation.
- The probability that a system or piece of equipment will operate as expected at a given point in time when used under the right conditions.
High availability systems are typically specified as 99.98% or above. When a piece of equipment is critical, high availability is essential. As reliability increases and maintenance downtime decreases, availability increases.
How to calculate availability?
System availability is calculated by dividing the equipment’s total uptime by the sum of uptime and downtime combined.
For example, if a piece of equipment runs properly for 1,000 hours but spends 20 hours in repair, you would divide 1,000 by 1,020. This gives you a total of 98.039%.
World-class availability is considered to be 90% or above while high-availability is considered to be 95% or above. In this case, our hypothetical piece of equipment passes on both accounts.