FAIs: When do you use conventional versus digital inspection methods?


Tony Holtz, Proto Labs

FAIs inspection methods investigation magnifying glass

[Image by theilr, via Flickr under Creative Commons license]

First article inspections (FAIs) can be time-consuming and costly, but they are a necessary step in getting medical devices from product design to production. Medical device manufacturers are likely familiar with the process, although most leave it to suppliers to handle. Even if that is the case, device makers should get involved and make sure that the FAI collection methods are as efficient as possible.

Manufactured parts are required to have detailed verification to meet the product design before production can continue, FAIs take the first parts from production and review them for conformance against the Technical Data Package (TPD) or Product Management Information (PMI) before production or assembly can continue. FAI’s also allows for traceability between orders and can be a starting point if/when the product fails.

There are many ways of obtaining FAIs. One common method is Geometric Dimensioning & Tolerancing (GD&T) through a conventional inspection report. Conventional inspection reports allow for an unlimited number of dimensions to be recorded by a number listing, nominal dimension, high and low tolerance, type of measurement used, and the actual measurement taken for each part in the lot that was required for the sample. This is important when detailed recording is required for the improved production of parts. However, because of the high level of detail and number of dimensions that need to be measured and recorded, the inspections can have a long completion time.

Another method of completing FAI’s is a process that uses digital scanning to compare the actual part to the CAD file. The method provides similar data as the conventional report along with a detailed visual aid and color map. The map displays the part using color contrast to show how far the part deviates from the nominal features. The color contrast is precise and can show deviations throughout a surface that might not be otherwise easy to measure, such as sink or warp.

Digital inspection reports are valued by engineers to verify critical and non-critical part features before assembly and offer an alternative (or supplement) to conventional reports while prototyping when speed and cost considerations are crucial.

One important note, digital inspections cannot always replace conventional inspection for critical components. But it can be used on production parts for the majority of non-critical components, while critical components generally would undergo conventional inspection reports.

Improving the methods of FAI can help medtech take advantage of rapid manufacturing processes, which can further speed product development and reduce manufacturing costs. Medical device manufacturers have often used rapid manufacturing practices, but only in the early phases leading up to engineering builds and FDA validation. Adding dimensional inspection reports through digital scanning allows manufacturers to work in a rapid manufacturing process further down the development cycle, even through the FDA 510 (k) submission.

Tony Holtz is a technical specialist at Proto Labs (Maple Plain, Minn.). 

Visit Proto Labs at Booth 103–104 at DeviceTalks Boston on Oct. 2

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