Reliability, what is it and why does it matter ?
When googling “what is reliability” you might not find immediately what you are looking for. That’s because reliability is a word used in a variety of professions and business area’s. From psychology to medical clinical trials and from the military to social research, they all use the word reliability in a somewhat similar but often slightly different context. In research repeatability and consistency are used for describing the reliability of a measure. To make matters even more complex the validity of the reliability is also important, having a reliable but non valid performance does not generate the expected results. Search for “reliability & validity" and you will find a lot of interesting articles.
In an industrial production environment, reliability has been around for a long time. Reliability Centred Maintenance (introduced in the 60’s), Reliability Engineers or Design for Reliability are well known and we all know what is meant. But do we really ? When I ask around during customer visits or industry events the answer to “what is the definition of reliability in industrial production environment” is often not straight forward. Makes you wonder. When asked what I think reliability should be the definition I use is "The probability that a component or system will perform a required function for a given time when used under stated operating conditions” (Source). The definition implies that we know the operating conditions, the required function and the given time. All elements that should be considered during the design of the component or system and during the operating life. Therefore design for reliability and reliability during operations are both essential for generating the expected performance. The industrial challenge is that they are not aligned.
During the design of a component or system the design engineers are often too far away from the operations or are designing a generic component or system that eventually will be exposed to certain specific operating conditions. The result is a set of instructions for operations and maintenance that are conservative and not aligned with the actual operating conditions. Reliability engineers are tasked to optimise the instructions for operations and maintenance to ensure that a component or system will perform a required function for a given time when used under actual operating conditions. The industrial challenge is that the requirements for operating conditions and given time are not static.
Technically running the components or systems faster while reducing maintenance intervals are common practises to improve output and reduce cost. On top of that the probability of failure will change over time, aging assets. The bathtub curve shows a different probability of failure for the different stages in the life cycle of the component or system. From stat-up / commissioning with decreased probability of failure (infant mortality) through normal operations with a quasi constant probability of failure to the end of life with an increased probability of failure (wear out). Upgrading the component of system, improving MTBF and MTBR while reducing MTTR can be considered when the reliability is good or when the technical end of life is approaching. The industrial challenge is that it’s not just a technical matter.
Economically a component or system can reach end of life sooner than technically justifiable. For example when a component or system will perform a required function for a given time when used under stated operating conditions the total cost of ownership can be significantly higher than replacing the component or system for an improved version. OPEX vs CAPEX on aging assets. The industrial challenge is that it’s not just an economical matter.
The industrial challenge is combining the design knowhow of components and systems with the operational knowhow and economical knowhow. Reliability engineering, whether in design or in operations plays a key role, understanding the probability that a component or system will perform a required function for a given time when used under stated operating conditions is fundamental for considering technical and /or economical decisions for upgrading or replacing.
Design with Operation and Maintenance!
Reliability gives you detailed insight in where manufacturing losses are not just in the downtime but also in quality, defects, complaints, loss of process control (or safety), and what the opportunities are. A lot of organisations do not yet use this to its fullest extent and allow the businesses to grow at a rate likely beyond their imagination. a 50 - 60 % utilisation of processes is quite standard for most companies, imagine simply moving to 75 - 80 % what that can provide.!!!
I agree that the people who design and manufacture industrial equipment are often too far from operations to fully understand all the different conditions in which their equipment will be used. However, with decent feedback loops, notably through their service engineers and customer complaints, they can build up plenty of knowledge over time and use this cumulated knowledge to design more reliability into their products.
Very nice article on some fundamental insights in manufacturing where agility, time to market and reliable product supply are key competitive advantages...