Make Reliability a Part of Every Decision

Expand your effectiveness in creating reliable products and processes

Published: Wednesday, February 17, 2016 - 12:36

Concurrent engineering is a common approach that pairs developing the product design and its supporting manufacturing processes through the development process. There are several reasons why this is a good idea.

Design engineers may require the creation of new manufacturing processes to achieve specific material properties, component performance, or mechanical, electrical, or software tolerances. And if they fully understand the manufacturing capabilities and full range of impacts and risks to process yield, quality, and reliability performance, they can make informed decisions concerning their design requirements. Making good decisions during design creates value. You can estimate the value by the magnitude of the span of outcomes for the decision.

By the same token, manufacturing engineers learn earlier and firsthand what’s critical to the product’s performance. They develop intimate knowledge of the design and understand those critical nuances not included on drawings or specifications that affect a product’s functional and reliability performance.

Discussions between the design and manufacturing teams often reveal areas of risk. Including a reliability engineer in these discussion may then extend the discussions to include the risks to meeting reliability objectives, too. Better, if the design and manufacturing engineers are able to fully consider the reliability impact on customers, they can incorporate that information into their decisions.

Existing reliability methods

Design for Six Sigma strives to achieve designs that are robust to the expected part and manufacturing variation that will occur. This is done by understanding the process capability for a part and setting design tolerances so that the expected range of variation (±1.5σ) minimizes the part’s contribution to system failures due to the component being out of tolerance, and thus not working.

Design for Six Sigma affects reliability because designs that are robust to manufacturing variation tend to be robust to changes to parts over time. As the material properties decay, polymers deform, or capacitance drifts, the robust design permits the system to continue to function normally.

It’s not always possible to achieve wide tolerance specifications for a given component capability, yet those often are a focus for the team to improve the process or include system monitoring to avert system failures, when possible. The concept of stress—i.e., strength—applies here and directly connects to field reliability performance.

If an organization uses design for Six Sigma during the design process, it also permits the team to identify elements of the design most at risk. The risk extends beyond manufacturing yield, since parts that are marginally acceptable tend to be less reliable overall. Another aspect that connects to reliability performance is the notion of process control and stability, which again improves field reliability performance, or at least predictability of reliability performance.

Lean strives to reduce waste from a process or design. This includes the careful examination of a process to indemnify and remove or minimize any unnecessary action, manipulation, storage, or delay. The intent is to make our processes as efficient and streamlined as possible, so that every step adds value to the product.

Lean tends to illuminate areas that increase reliability risks (extra handling or movement increase chances of damage, for example). Furthermore, lean practices tend to reduce the need for testing, evaluation, and monitoring because the opportunities for mistakes reduce. A lean design, for example, might use a single type of screw with one torque setting. The manufacturing process removes all but the one type screw and uses a single torque driver to install it. This eliminates the parts and tool management overhead for many parts and tools, and streamlines the operator training and decision making.

Extend the lean concept across a product, and it improves the ability for the design and manufacturing process to create the product correctly, thus improving the field reliability performance.

Emerging technologies occur, it seems, at an increasing pace. New techniques, procedures, materials, attachment schemes, and more, arrive nearly every day. A general guideline is to flag for additional attention anything that is “new”: new to the industry or customers, new to the design or manufacturing process, or new to our way of thinking.

As reliability engineers we examine and attempt to characterize anything new with respect to its impact on field reliability performance. A few basic questions often start with how will it fail and when it will fail. Although this is a rather negative approach, it helps the entire team understand any limitations or boundaries concerning reliable performance for the new material, component, or process.

Summary

Product reliability occurs as a result of the many decisions across the organization. Considering that the scope of reliability engineering spans the entire product life cycle and involves nearly every aspect of bringing products to market or operating a plant, we must hone our skills to understand and advocate for including reliability thinking with every program and process across the organization.

By broadening the conscious consideration a decision’s effect on the eventual impact on reliability, we in effect expand our reach as reliability professionals and our effectiveness in creating reliable products and processes.

About The Author

Fred Schenkelberg

Fred Schenkelberg is an experienced reliability engineering and management consultant with his firm FMS Reliability. His passion is working with teams to create cost-effective reliability programs that solve problems, create durable and reliable products, increase customer satisfaction, and reduce warranty costs. Schenkelberg is developing the site Accendo Reliability, which provides you access to materials that focus on improving your ability to be an effective and influential reliability professional.