Non-Destructive Seal Testing
Published: May 9th, 2012
With its Seal-Scan non-contact airborne ultrasound technology, PTI Inspection Systems (www.ptiusa.com) provides a non-destructive method for inspecting medical pouch seals. Seal-Scan tests seals end-to-end for overall seal quality and variations in seal uniformity, finding defects that are often undiscoverable through visual inspection.
“In most cases people have been using human vision, which is inherently unreliable. The quality of the seal is dependent on physical properties only and has little to do with the visual appearance of the seal area,” says Oliver Stauffer, project leader.
In visual inspection, operators can detect only 80% of defects at best and the ability to detect defects diminishes as time spent inspecting increases. ASTM’s F1886 standard defines the probability of detection of 75 micron channel leaks as from 60 to 100%.
Seal-Scan is offered as the Seal-Scan 525 unit for off-line inspection, and the Seal-Scan 540 for automated 100% on line inspection.
“Seal-Scan has been proven as a validated solution for seal quality inspection. We are catching the defects—missing and incomplete seals, potentially weak seals prone to delamination—that can compromise package sterility and lead to recalls,” Stauffer says.
On-line scanning uses L-Scan mode, a point-to point linear scan across the seal with a pass/fail result. As an analytical tool for more in-depth inspection, the off-line unit in C-Scan mode compiles multiple linear scans.
“Peel strength is a function of the uniformity of bond between seal materials and determines if they are uniformly bonded when the material is peeled. A uniform seal—meaning an overall good quality seal—produces a stronger peel strength.
“If you have a seal that is not uniform and has a lot of variation in quality, this will likely not produce a good result using either peel or seal strength test methods. Seal-Scan captures this information non-destructively. We have done studies showing the Seal-Scan test results correlate to seal strength results,” Stauffer says.
The technology requires no sample preparation, features a fast test time, eliminates package waste from destructive tests, and provides a repeatable test with quantified results supporting statistical process control.
With Seal-Scan, sealing results can be referenced to improve the sealing process to ensure quality seals at the out set.