The Purpose, Objectives, and Methods of Reliability Engineering

What criteria do you use to determine if a product is satisfactory?

Standard quality control procedures at a manufacturing facility will involve conducting set inspections and tests. The product is termed "ready for use" if and only if it satisfies all applicable specifications. However, if you have to use the warranty system twice or more before the warranty period ends, you cannot say that you made a good buy.

When we think of reliability, we think of things like dependability and dependableness. As a result of engineering, we now have a more complete metric for gauging product quality, as time is also factored in. To rephrase, it is no longer important to us whether or whether a product serves its intended function when making a purchase. Instead, we want to make that the product works as advertised for as long as practical under real-world conditions.

Reliability engineering aids businesses in generating more dependable products and guides maintenance crews in extending the MTBF (mean time between failures) and useful life of assets.

If you're interested in learning more, keep reading the following portion of the post, where we'll cover the following:

• the concept of dependability
• dependability engineering's groundwork
• how reliability engineers may aid in making equipment more reliable by covering the basics of reliability evaluation

How would you define dependability?

Reliability is the extent to which a part or system can continue to function as expected under normal conditions.

To rephrase, the more reliable system is the one that lasts longer and experiences fewer major issues under identical operating conditions.

Risk, here expressed as probability, is inherent in gauging dependability since no one can predict the future or guarantee that a product would not break after X hours of use. Among other things, we may utilize dependability estimates to foretell whether or not a system will continue to function normally after x number of hours or days of use. Inevitably, a system's reliability will improve greatly when it's initially implemented, only to deteriorate as time passes.

It's common practice to equate "reliability" with "durability," "quality" with "availability," and so on. You shouldn't get the two ideas mixed up, even though they sound similar. What follows is a brief explanation of each possibility.

 

Contrast: durability versus dependability

A product's durability may be defined as its ability to withstand normal use over its expected lifetime without requiring significant servicing or replacement parts (definition stolen from Tim Cooper).

The key difference between dependability and durability is that the former is focused on the amount of time a product may function despite failures, while the latter seeks to minimize the occurrence of failures.

In addition, the durability characteristic stands in for a tangible attribute, whereas the dependability feature may be applied to both physical and digital systems.

Depending on the product and its intended use, durability might be quantified in terms of operating cycles, years of life, or even decades.

 

Comparing quality with reliability

It's not easy to put words to the idea of quality. One common method for defining quality is looking at the factors that affect it. That's how we get at the idea of eight different types of quality.

Since we can think about dependability (and durability, if you look closely) as one degree of quality, this is a straightforward way to distinguish between the two.

To further disentangle the two concepts, we might define dependability as the extent to which a system retains its initial quality after repeated use.

 

Distinguishing between availability and dependability

Availability is defined as the amount of time that a system is fully operational and ready to perform its intended tasks.

This word is commonly used to describe the accessibility of cloud computing resources in the IT industry. The highest-availability systems boast a 99.99 percent uptime (meaning they are unavailable for just 52 minutes per year, often due to scheduled maintenance).

Availability is affected by reliability and maintainability. There will be fewer breakdowns and more availability with more reliable systems. The same holds true for maintenance: the faster you finish it, the less impact it will have on availability.

 

What exactly is meant by the term "reliability engineering"?

Reliability engineering refers to the use of engineering theory and practice in a methodical approach to create more dependable products at a lower cost. From the initial stages of product development all the way through the product's operational and maintenance phases, reliability engineering may be applied.

However, the greatest gain from reliability engineering is the identification of possible issues before they become major problems. Finding a reliability problem early in the product lifecycle, such as during design, can significantly cut costs later on (i.e. by eliminating the need for a significant product redesign after it is already in the market). The chart down below shows how this works in practice.

The goals of reliability engineering are as follows:

• Through the use of technical knowledge and processes, avoid certain failure types and reduce the occurrence and severity of failures.
• When things go wrong despite precautions being taken, it's important to isolate the source of the problem and fix it.
• Finding a way to bounce back from setbacks if the causes aren't fixed.
• Methods for analyzing reliability data and projecting the expected dependability of new designs should be applied.

If you look closely, you'll see that the list's objectives are structured in a way that parallels the logical evolution of employing different dependability methods. It would be futile to try to add redundancy for all of the failures if some of them may be prevented with simple design improvements. For the most efficient and economical implementation of dependability practices, it is essential to follow the aforementioned steps in the order presented.

 

What you need to know about reliability testing

The end goal of reliability testing is to amass sufficient qualitative and quantitative evidence to conclude that our component/system does not provide an unacceptable level of risk when employed. Reliability engineering relies heavily on this technique.

For our purposes, we shall define risk as the sum of two quantities: the frequency with which a failure will occur and the severity of that failure (what is the fallout of the failure; can include safety risk, potential secondary damage, cost of spare parts and labor, production losses, etc.).

 

The causes and types of failure must be understood

It's not always easy to determine what led to a negative outcome. If this were not the case, there would be no need for reliability engineers or failure analysis.

The failure modes and processes of complex systems can only be understood and addressed with precision if the system is first "broken down" into its constituent parts. This enables you to look at each one alone and in context with the others.

In addition to the aforementioned, it is important to think about how the system interacts with the user and the environment, as misuse and poor working conditions can reduce product reliability.

 

Activities and methods typically used in reliability engineering

Depending on the complexity of the system and the nature of the system, we may employ a wide variety of tactics and actions as part of our reliability engineering efforts, including the following:

• Cause-and-effect investigation (RCA)
• Reliability-centered maintenance (RCM)
• Analysis of Failure Mode and Effects and Criticality Analysis
• The physical foundations of FMEAs for Design and Process Failure (PoF)
• There is an internal evaluation system
• Examining the Blocks' Reliability
• Examining Field Information
• Explore the tree of faults
• Removal of a potential failure spot (SPOF)
• The Study of Fallibility
• Examine the potential threats to daily operations
• The failure rates and other relevant information can be gleaned from a review of the maintenance records
• Information gathered from a battery of tests to determine how effectively a system or component operates under duress

All of these techniques can help us locate vulnerable spots in our system and estimate how likely it is that fixing them would prevent further issues. If the threat is serious enough, we have to take steps to fix the problem. Options include making changes to the design (such adding redundancy), implementing detection control, providing maintenance instructions, and educating users.

 

Assessment of reliability on a quantitative scale

Consistency, as I mentioned at the outset of this piece, is often a roll of the dice (probability). Since you'll be using numbers and statistics to define risk, it's crucial that everyone in the team has the same expectations for what constitutes an acceptable level of risk.

Because of this, it's essential to be precise when describing problems and offering solutions. However, due to a lack of statistical data and other uncertainties, some experts in the field of dependability recommend concentrating on potential solutions rather than failure scenarios.

How can the equipment in a facility be made more dependable by the reliability engineers responsible for it?

Reliability engineers may help increase the dependability of equipment by contributing to the enhancement and optimization of on-site maintenance procedures. A number of these will be discussed below.

 

Contributing to the research, development, and design of replacement parts

There is no limit to the wear and tear that can occur from daily use. Most assets will require continuous replenishment of replacement parts to ensure optimal performance.

Companies that have access to CNC machines or 3D printers may opt to build their own components instead of constantly restocking their supply of spare parts. Furthermore, they may be using obsolete machinery for which components are no longer manufactured, or they may be experiencing a severe malfunction that calls for a unique component.

Together with the upkeep crew, reliability engineers may design, test, and produce high-quality replacement parts that significantly improve the asset's uptime.

Expertise in determining and interpreting causes of failure is a key competency for reliability engineers. Therefore, they may be tasked with doing a root cause analysis (RCA). By analyzing data such as equipment failure rates and other metrics, as well as original equipment manufacturer (OEM) manuals, maintenance procedures, and equipment maintenance records, they can provide solutions to the underlying problems.

One approach to addressing such reasons is through RCM processes.

 

By focusing on the right failure modes, we can make sure that our maintenance efforts are well spent

This follows on from the last section. Now that we know what you aren't doing (which sorts of failures you aren't preparing for), we can turn our attention to the things you could be doing wrong.

The vast majority of companies eventually face a situation when they do maintenance on an asset, yet it still breaks down. Incorrect actions by maintenance experts, such as ignoring the right sources of failure, are likely contributors. Considerably beneficial is using cause and effect analysis here.

Similarly, reliability engineers may monitor the status of various maintenance procedures and suggest changes as needed. The management team may check to determine if the maintenance staff is performing value-added, problem-solving preventative maintenance rather than relying on outmoded practices. All of these should be simple to find in a reliable CMMS.

Check out our guide to learn more about CMMS. The purpose and operation of a computerized maintenance management system (CMMS) are discussed.

Finally, reliability engineers may lend a hand when choosing the right sensors and equipment for condition monitoring in order to implement cutting-edge maintenance strategies like condition-based and predictive maintenance.

 

Last words

Efforts to improve reliability engineering bring severe effects. Regardless of the size of your organization, dependability tactics may be used using the suitable knowledge.

There is a win-win for everyone if businesses keep spending money on reliability. The production company reaps the benefits of higher-quality items, the maintenance team reaps the benefits of simpler maintenance, and the end user reaps the benefits of fewer performance worries during the lifespan of the product. There are no losers and no losers in this scenario.