Using Failure Analysis to Improve Reliability

Three things that can upset your day’s schedule: product failures during testing, product failures during use, and production equipment failures. You go to work with a nice plan for the day. Instead, you get to start figuring out why the failure occurred.

Figuring out the root cause of the failure is the next step. Failures are often because a component or a joint between components failed. So, a metallurgical analysis of the component or joint must be performed.

The information gained is used to identify the root cause of the failure. Then design, supplier, or manufacturing changes can be made to prevent the problem from occurring again.  

Learn more: Metal Conversations podcast episode on failure analysis

Failure analysis

Failure analysis of a component/joint is used to determine:

• How the materials degraded.
• The failure mode and mechanism.
• Whether the materials meet their composition, microstructure, and property requirements.
• Whether the component/joint was fabricated properly.

With this information it’s possible to determine the metallurgical cause of the failure, e.g. overstress, fatigue, improper heat treatment, wrong alloy, … Combining that with the failure background information we can start to figure out where to focus attention regarding the root cause – design, fabrication process, use conditions, …

When the root cause is identified, measures are put in place to prevent the failure from recurring, at least due to that root cause. Here are some examples:

• Use high-strength stainless steel fasteners instead of zinc plated steel fasteners to eliminate hydrogen embrittlement failures.
• Put testing in place at component supplier to ensure that parts have the correct strength, preventing parts from fracturing during use.
• Reduce contact force between rollers and conveyor belt to stop belt adhesive wear.
• Clean up electrical power to reduce voltage spikes that caused production equipment motor acceleration and deceleration, which caused parts being driven by motor to flex back and forth, resulting in fatigue cracking and fracture.

For all these examples, understanding the metallurgical and use factors that contributed the failures was key to quickly identifying solutions that resulted in better product and equipment reliability.

Failure analysis process

Here’s a summary of the process I use:

1. Review the failure with the engineering team. This includes reviewing photos and drawings of the failed component or joint and discussing the failure circumstances.

• Identify the metallurgical analyses to perform and the samples to be evaluated. Selecting the appropriate metallurgical analyses and samples is important.

• Perform the analyses and review the data. The analysis data and background information are used to identify the failure mode and mechanism, whether the materials had any metallurgical deficiencies, and whether there were fabrication problems.

• Meet with the engineering team to review the analysis findings and discuss possible root causes of the failure and next steps. While more information may be needed to identify the root cause, the failure analysis is crucial for helping point in the right direction. If a failure is related to the component’s design, the failure analysis findings are used to guide design changes.

Two common not-systematic approaches

It’s unlikely a root cause will be identified without the information gained from a failure analysis. Having meetings to brainstorm potential root causes or making educated guess design changes are not productive, not systematic, and lead to lingering problems. Yet, both are commonly used.

Systematic approach for improving reliability

There are many possible reasons for product or equipment failure. Failure analysis is a powerful tool for systematically learning the metallurgical and use factors that contributed to a failure. Having this information enables well-informed, effective design, supplier, and manufacturing decisions to improve product and equipment reliability.

Want to learn more - check out our Metal Failure Analysis course.

Also, check out this classic book about component failures: Understanding How Components Fail, 3rd Edition