Criticality, or the risk that something will fail and cause negative effects on the system, is the starting point of reliability. To achieve the optimum reliability in machines and equipment, you need to understand Overall Machine Criticality (OMC). The concept of OMC lets you analyze risk profiles and adjust your maintenance efforts to ultimately achieve precision and efficiency.
What is Overall Machine Criticality?
Overall Machine Criticality or OMC is the criticality value based on the risk profile of a machine. The OMC can be calculated by multiplying the Machine Criticality Factor (MCF) by the Failure Occurrence Factor (FOF).
The MCF is related to the effects of machine failure, including the extent of the impact on the operation and the cost of repairs. The FOF, on the other hand, is related to the probability of failure.
Machine Criticality Factor (MCF)
To estimate the MCF, you need a thorough understanding of the effects of failure on your operations system. You also need to know the costs required to resolve failure and resume operations.
The MCF ratings range from 1 to 10:
- 1 is a low risk of causing minimum downtime and repair costs
- 10 is a high risk of prolonged downtime, safety hazards, and expensive repairs.
For example, a machine that is critical in your production area and requires expensive parts to repair would have a high MCF.
Having predictive tools or methods that allow the early detection of failures can significantly reduce the MCF. Methods and tools such as oil or wear debris analysis, metal temperature analysis, motor current tests, proximity probes, etc. can detect machine failures before they occur. If your facility has access to such predictive methods, consider them and adjust your machine’s MCF accordingly before calculating your Overall Machine Criticality.
Failure Occurrence Factor (FOF)
To estimate your machine’s FOF, you must have an accurate and detailed record of its repair and failure history. In addition, you need to compare your machine’s performance with similar machines.
The FOF ratings range from 1 to 10:
- 1 involves having a long history of use and zero failure events or no signs of failure in the future
- 10 means the machine is prone to failure or failing within the first year of service or repair.
If a history of repair and failure is not available, FOF can be estimated using the Reliability Elements Quotient (REQ) before you calculate Overall Machine Criticality.
Reliability Elements Quotient (REQ)
The REQ identifies the factors that affect the occurrence of failures in machines. To estimate the REQ for your Overall Machine Criticality calculations, a scoring system with a 1 to 10 range is used. High REQ means a high probability of machine failure. This scoring system includes the following elements:
- Machine duty or the compilation of operations or duties that can cause the machine to fail prematurely. A mixer that operates at high pressure, high loads, and multiple batches would have a higher score than the one used at a lower pressure, with lighter loads, and with less frequency.
- Lubricant performance or the quality of the lubricant used in preventing friction and wear. High scores in this area mean that the lubricant is not ideal for the machine or is of poor quality.
- Lubricant effectiveness or the process of applying lubricants to machines to prevent wear and extend performance. A machine that requires frequent or high levels of lubrication and shows signs of wear frequently will get a high score on this criterion.
- Environmental contamination or the likelihood that the surrounding area, process, and other environmental factors can contribute to failure. A machine exposed to a dirt-heavy environment would have a higher score than one in a clean and isolated area.
- Predictive technologies or the presence of tools and methods that help detect early warning signs of failure. High scores would be given to a machine not inspected daily for preventive maintenance or not subjected to oil analysis for signs of wear.
Overall Machine Criticality Matrix
By multiplying the MCF and FOF ratings, you get Overall Machine Criticality which will allow you to classify machines as low-risk or high-risk. The best way to see the OMC values and their implications is by the Overall Machine Criticality matrix, where you plot the MCF values against the FOF values.
Through the OMC matrix, you can easily observe the machines in increasing or decreasing risk. Thus, you can identify the immediacy or level of attention you need to assign to these machines. Low-risk machines do not need immediate attention, while high-risk machines need immediate and close attention.
Criticality Analysis with Redlist
Software like Redlist can help you through the complicated process of risk analysis of machines. With digitized data and real-time recording, computing your Overall Machine Criticality is immediate and accurate. To learn more about our Computerized Maintenance Management System (CMMS), schedule a free demo with us today!
