Multi-camera vision system verifies sterile medical
device and supply package integrity.
John Fouts, Bhaskar Ramakrishnan, and Luo Cheng
Vision system inspects seal
quality on flexible packaging
It goes without saying that Class II and III
medical device and supply manufacturers can
ill afford the risk of sterile product contamination. However, as hygienic as the packaging
process is, the potential still exists for foreign
materials to become trapped between layers
of heat-sealed material. In some cases, such
debris may form micro channels large enough
to breach the seal to ambient, allowing bacteria to enter later.
Manual inspection of package seals tends
to be time consuming and error prone. After
all, contaminants such as hair and hidden particles in the seal can be extremely challenging for people to see, leading to mistakes or
oversights. Moreover, damaged package seals
may also have microscopic holes or tears that
human eyes cannot see.
Needless to say, if such packages make
their way into hospitals
and other medical settings, it can compromise
not just the sterility of
the medical devices and
supplies, but also the
health of patients.
engineers at DWFritz
Automation Inc. (
Wilsonville, OR, USA; www.
DWFritz.com) have developed an automated seal
inspection system called
ASI. The system relies on
a multi-camera machine
vision system designed to
perform 100% inline inspection of packages on a manufacturing line to ensure that sterile products remain sterile throughout the
The ASI system was demonstrated in April at
the Automate 2017 trade show and conference
in Chicago. Designed to inspect for seal integrity and other defects on packages formed from
flexible poly films, this system was designed
to inspect packages formed into eight individual pouches in two parallel rows of four each,
filled with surgical devices and sealed with
perforated and breathable Tyvek lidding.
To inspect all of the
seals surrounding each of
the eight pouches, the ASI
picks up each package
and precisely moves it at
a rate of 250mm/sec over
two arrays of upward-fac-
ing cameras with inte-
grated strobe lighting (Figure 1). During the
12-second inspection cycle, no less than nine
cameras acquire 378 images to detect and clas-
sify defects down to less than 50 microns.
Production line integration
While the trade show demonstration was a
standalone system inspecting surgical sponges,
at the actual customer site the ASI system is an
integral part of the production line that’s linked
via automated conveyor to the packaging equipment, which fills similar packages with various
types of medical devices and supplies.
During operation, as the package enters
the system via infeed conveyor, it’s sensed
and then input to a Control Logix PLC from
Allen-Bradley (Milwaukee, WI, USA; www.
ab.rockwellautomation.com), which controls machine operation, triggers an output to
raise lift fingers under the package. When the
package is in position on the elevated infeed
John Fouts, Senior Controls
Software Engineer, Bhaskar
Sales Engineer and Luo Cheng,
Senior Vision Engineer, DWFritz
Automation Inc., Wilsonville, OR,
USA ( www.DWFritz.com).