5 Key Steps in Reliability Test Planning

Follow these important reliability testing steps to assure success!

How do you know whether a medical device will perform reliably in the field?  Unless your design is perfect from the start, a design in reliability will need a cycle of Test, ‘Fix’, and Test again. Reliability testing is an essential part of medical device quality management to assure performance over time and design fail-safe operation. Proper testing requires proper planning.

There are five key steps to follow for reliability test planning and preparation to assure success.

STEP 1 – ESTABLISH REQUIREMENTS

To begin, design requirements are captured for reliability. This includes defining the usage, performance, environmental, fail-safe, and any allowable degradation over time. This may include whether certain elements of the product are meant to be repairable or replaceable. From a project management perspective, this step also includes outlining the reliability growth schedule of the product.

STEP 2 – FAILURE ANTICIPATION

Next, it’s important to understand that all products will eventually fail and that some could fail within their indicated use period. We need to anticipate, prevent or control these potential failures in our design and prepare a way to track and address them. To do this, we can apply the ‘Triple F’ methodologies, where we can use the Failure Mode Effects and Criticality Analysis (FMECA), Fault Tree Analysis (FTA), or Failure Reporting and Corrective Action (FRACA).

• FMECA is a design tool that addresses failure modes, effects and causes from the bottom up, down to the component level as necessary.
• FTA is a design tool that addresses failure from the top down at the system or user experience level.
• FRACA establishes how failures are reported, documented, and corrected through the design and then the post-market phases. A consistent method and classification of failures is important through the product lifecycle.

STEP 3 – GENERATE RELIABILITY MODEL AND BUDGET

For this next step, a reliability model that will represent the product is created. This may be a model of hardware or software components and/or a model of different operating modes and available functions and features. A reliability block diagram is a type of reliability model that defines the components to be tested. A reliability ‘budget’ is a way of taking your overall allowable product reliability or failure rate and dividing it up for specific types of failures or components. For example, to achieve an overall 99% reliability with ten components, each component must have 99.9% reliability. Each component ‘gets’ a reliability budget or goal.

Use the reliability block diagram to identify critical components and quantify reliability down to the component level. The more detailed your model is in this part of the process, the more helpful and accurate your reliability testing will be.

It is also very important, even in these early stages of design, to consider supplier reliability goals.

STEP 4 – RELIABILITY PROGRAM TEST PLANNING

The reliability program will include several different tests, evaluations, demonstrations, and analysis activities. These tests may be exploratory, intended to demonstrate success, or intended to force failures.

From this step, an importance list is generated that emphasizes critical safety issues and proof that the design created addresses these with a high level of statistical and business confidence. As mentioned, reliability growth planning drives design improvement in a quantifiable manner, just like how product costs or fabrication time is managed. Failure rates, costs, and time are all project parameters that are calculated and driven down.

Collaboration is required between engineering stakeholders and reliability subject matter experts as the design reaches the final stages of development. You’ll need project management buy-in for this process so it will operate under full approval for the necessary budget and resources. It will be almost impossible to optimize test designs without collaboration with management.

In reliability testing, a stress scenario is a situation where extreme stress is introduced into the system to see how something performs under pressure. This gives a richer picture of the device’s performance in various scenarios and reveals priorities for refining the device development. Detailed test planning will involve specifics like the test locations, fixtures, sample sizes, and the testing subject matter experts who will participate in the process.

STEP 5 – EXTENDED TESTING

Finally, additional and continuous testing may be needed outside the organization. Outside lab testing may have already been employed. With this element, supplier reliability results may have already been reviewed and accepted. To deep dive further into this last step, extended testing may also be applied.  This can include field testing, clinical trials, First-In-Man trials, Pre-commercial use, serviceability tests etc. These activities can eventually and naturally progress to using post-market data to improve the design.

It is necessary to monitor the process for last-minute design and production changes, including relationships and change control with external suppliers. Extended testing lets us seize these opportunities to further refine the product. Every extra percentage point of reliability can help provide favorable patient outcomes.

HAVE THE RIGHT RELIABILITY TEST PLANNING PARTNER

At Network Partners, we use advanced data analysis to provide deep insights into your quality management process and reliability testing. We collaborate with our clients to establish reliability targets that assure statistically justified product performance.

Contact a Partner today to create a quality management plan for tomorrow. We provide medical device reliability test planning expertise to minimize expenses while bringing life-saving products to the people who need them.