Developing a new product or improving an existing one starts with an idea. But moving from idea to reality involves a series of processes, testing, and troubleshooting. One of those processes is taking the product through a design failure mode and effect analysis (DFMEA).
DFMEA may also be performed on the assets that create these products, and the process of designing them. Here, we’ll explain how a failure mode and effects analysis (FMEA) and DFMEA are related, why DFMEA is important, and how to perform it.
What is DFMEA?
DFMEA is the process of examining all the potential failures that could occur when designing a new product. From making molds to soldering the final connections, a lot can go wrong when building prototypes – which is why it’s important to account for all possible failures before starting production on a larger scale.
During DFMEA, each failure and its results are assigned a severity rating, an occurrence rating, and a detection rating. Those three numbers are then multiplied together, resulting in a risk priority number (RPN):
RPN = Severity x Occurrence x Detection
Failures with the highest RPNs are more severe. Knowing this can help teams mitigate the most critical failures, reducing or eliminating their likelihood during production.
Ideally, companies perform DFMEA prior to launching their product. While they may not eliminate every potential failure, a successful DFMEA will result in a better product design and happier end users.
DFMEA vs. PFMEA
Process failure mode and effect analysis (PFMEA) and DFMEA are both branches of the broader failure mode and effects analysis, also called simply FMEA.
PFMEA looks at the entire process and identifies potential failures in the system. For example, in manufacturing, a PFMEA may look for failures in processes like painting the product, assembling, or shipping.
However, a design failure mode and effect analysis focuses on failures in specific areas of the design. On the product development side, the DFMEA investigates how the product may fail, such as when it’s used in a certain way or exposed to certain temperatures. Assets used in manufacturing these products can also undergo a DFMEA to ensure the assets perform as expected.
What is a Failure Mode?
A failure mode is anything that causes the product or process to perform outside of the expected parameters. It can range from a very minor error that is barely noticeable and doesn’t impact performance in any way, all the way to a major failure resulting in product recalls and a shut-down production line. In the most severe cases, a failure mode could end up causing injury to the end users or even result in lawsuits.
Explaining Failure Mode Effect Analysis
Identifying the failure mode is important, but it’s only the first step in a failure mode effect analysis.
The purposes of FMEA is to determine why the failure happened, how important it is to correct the failure, and then take steps to keep the failure from happening in the future. Whether you’re looking at a process, a design, or an entire system, FMEA is a critical component of ensuring maximum uptime, safety, and end-user satisfaction.
How Does DFMEA Work?
Design failure mode and effect analysis works by assembling a group of people with expertise across the design being analyzed. Together, these people brainstorm all the ways the design may fail.
Team members can recall past experiences and use their knowledge to think of how failures might happen and what the results of those failures could be. For existing designs, the DFMEA can use past data to help determine the failures and their effects.
Then together, the team decides how to solve these problems proactively. This could include making changes to the design, parts, materials, or other elements of the design and production process.
DFMEA Example
Let’s say an engineer develops an asset to be used in packaging a final product. During prototype testing, a DFMEA identifies a failure in the tape dispenser mechanism. It occurs after about 100 hours of use, and causes tape to not dispense as needed. In turn, about 50% of the packages are sealed incorrectly and, in some cases, the product spills out of the packaging and becomes unusable.
This is a major problem. During the DFMEA, the team ranks the rate of occurrence at 7, the severity at 10, and the detection a 2. This results in an RPN of 140 and the team determines the issue needs to be addressed.
After examination, the team discovers that the issue is caused by a fault in the bearings which allow the dispenser to spin freely. The team may choose to address this by recommending regular lubrication and maintenance, changing the materials used in the dispenser, or making some other change to reduce the likelihood that the end user of the asset experiences this failure.
How To Perform DFMEA
Performing a DFMEA can be a very in-depth and time-consuming process, but catching design errors and fixing them before they can cause major issues is incredibly important. Here’s how to get started:
- Choose the design to be analyzed.
- Assemble a cross-functional team of experts familiar with different areas of the design
- Identify all possible failure modes.
- Identify the root cause(s) for each failure mode.
- Assign the severity, occurrence, and detection scores to each failure identified.
- Identify the risk priority number by multiplying each of these scores together.
- Take action to reduce or eliminate the risk of the failures, beginning with the highest RPN scores.
- Once the changes have been implemented, perform another DFMEA to determine if the RPN score has been reduced.
A computerized maintenance management program (CMMS), can be key in increasing reliability and improving RPN scores. By tracking assets and gathering performance data, your team will be well-equipped to perform thorough equipment analyses and boost performance with targeted maintenance.