We’ve recently partnered with our friends at the University of Tennessee (Knoxville) Reliability & Maintainability Center to offer reliability & training opportunities in both instructor-led and online formats (more about that below).
As a result, we’ll be writing a series of articles to introduce you to some key concepts in reliability and maintainability.
This is the first article in the series, and we’re going to keep it basic and foundational by giving a quick and easy definition of reliability and maintainability.
What is Reliability?
When discussing reliability at a plant, reliability is defined as “The probability of a product performing its intended function under stated conditions without failure for a given period of time.” (Thanks to our friends at the American Society of Quality for that reliability definition).
A top quartile reliable plant is typically more productive, has more stable processes resulting in higher quality, lower costs, and has a more engaged workforce. There is a strong correlation with related key performance indicators and highly reliable plants. Often it is linked to the practice of more preventive and predictive maintenance (and less reactive maintenance).
Reliable plants are safer plants as well–when reliability metrics go up, safety incident metrics tend to go down.
The reliability of a plant can be measured using MTBF (mean time between failure) and maintainability can be measured by MTTR (mean time to repair). Metrics such as Overall Equipment Effectiveness (OEE), Total Effective Equipment Performance (TEEP) or Asset Utilization can be used to assess overall equipment health.
What Is Maintainability?
Again according to the American Society of Quality, maintainability is defined as “The probability that a given maintenance action for an item under given usage conditions can be performed within a stated time interval when the maintenance is performed under stated conditions using stated procedures and resources. Maintainability has two categories: serviceability (the ease of conducting scheduled inspections and servicing) and repairability (the ease of restoring service after a failure).”
The words Maintenance and Maintainability are often used synonymously and that is incorrect. Maintenance is the act of providing the service of checking, repairing or replacing. Maintainability is a designed-in parameter that should be done when designing a piece of equipment/machine. Just a few of the numerous design considerations are standardization, accessibility, and modularity. For example, modularity addresses the ability for removal and replacement by smaller units (modules) that should be built into the machinery and equipment, including:
- Is each module easy to handle by one person ?
- Are disposable modules easy to get to without damaging other parts?
- Is the design such that long-life parts have to be disposed with disposable short-life parts?
Conclusion: Your Intro to Reliability and Maintainability
Plants benefit in many ways from increasing reliability and maintainability. Keep your eyes on our blog for additional articles on reliability and maintainability and we’ll go into more details and cover things in more depth.
This article is a collaboration between the University of Tennessee Reliability and Maintainability Center (RMC), Convergence Training, and RedVector. The University of Tennessee Reliability and Maintainability Center (RMC) provides professional development training, assessments, company studies and a University-sanctioned certification based on measurable results (safety, culture, quality, throughput/uptime and cost). Convergence Training and RedVector both offer online training solutions related to reliability and maintainability, and RedVector offers online courses that can be completed as part of the UT-RMC’s Reliability & Maintainability Implementation Certification (RMIC) program.
Don’t forget to download the free PDCA Cycle infographic below before you go.
FREE PDCA Cycle Infographic
Download this free infographic of the Plan-Do-Check-Act (PDCA) cycle commonly used for quality control, project planning, and continuous improvement.