AVT Cameras Inspect Airbag Inflator

Manufacturer of high-pressure gas chargers uses AVT Guppy cameras for 100% leak control.

Airbags have become a standard equipment of most modern cars. Driver and passenger airbags, side airbags and curtain airbags deploy within milliseconds to protect our lives in case of an accident. The bags are inflated by highly compressed gas – commonly nitrous oxide (N2O) – contained in a metallic charger. Ensuring the proper functionning of these chargers is key to guarantee the correct deployment of the airbag and therefore passenger safety.

MOS Industrial of Taiwan specializes in high-pressure gas packaging and is the second largest high-pressure cylinder manufacturer in the world. Applications range from cream wipers to tire inflators via airflow power cleaners – and airbag inflators. These are small metal cylinders of approx. 3½” length (9 cm) with a valve at one end.

100% Inspection for 100% Safety
As a failure could have fatal consequences for motorists around the world, airbag inflators are subject to very high quality standards and submitted to a 100% inspection. The highest risk lies in defects in the cap and its valve as it could cause gas to be lost partly or completely before the airbag is triggered. The consequence would be insufficient pressure for the airbag to inflate properly.

In order to guarantee the quality and safety of its products, MOS decided to implement a 100% inspection system of the inflators’ caps using machine vision technology. The system automatically checks every single cylinder for up to 5 defects: cracks, valve positioned upside down, bends, rust, and concave instead of convex surface.

Two parallel control lines inspect the gas chargers after the filling process and prior to shipping. A conveyor belt delivers the cylinders into a cogwheel that positions them in front of a camera. Because the inflators are randomly fed in, two cameras face each other in order to capture the head whatever the orientation of the cylinder. When the inflator passes in front of the cameras, two sensors measure where the head is located in order to trigger the appropriate camera.

The cameras used are Guppy F-033B monochrome cameras from Allied Vision Technologies. The Guppy is a very small and inexpensive machine vision camera with a digital IEEE1394a interface. The Guppy F-033B model features a monochrome CCD-sensor from Sony (ICX424) with VGA resolution (0.3 Megapixel). All four cameras are fitted with 25mm Fujinon lenses and combined with an axial white lighting from Advanced Illunination.

The images are transmitted via FireWire bus to the processing unit, in which they are analysed using Open eVision, an image-processing software provided by Euresys, an AVT Certified Vision Software Partner. Bad products are automatically ejected on a separate tray.

AVT Guppy Checks 13 Pieces per Second
Because each inspection line requires two cameras with lighting, the very small form factor of the AVT Guppy was perfectly suited for this application. With 58 frames per second at full resolution, the Guppy F-033 can easily cope with the pace of 13 pieces inspected per second that the system delivers today and could manage faster speeds.
Finally, its attractive price made it a perfect choice for this cost-sensitive application.

In terms of service, MOS can rely on Allied Vision Technologies’ Taiwanese partner G4 Technology for local support, backed up by AVT’s own Asia-Pacific subsidiary in Singapore.

Thanks to its 100% quality inspection using AVT cameras, MOS Industrial contributes to producing reliable safety equipment that saves lives on the road every day.