Author: Mr. Preetam Sheregar.
Designation: Manager.
Department: Machine Tool Division and Vision Systems.

The client needed an industrial vision system to inspect the Cannula for correct orientation, heal distance of catheter w .r .t Bevel and tip forming of sleeve on their Final & Tip forming assembly machines.

On a production line that moves 50 parts/min, manually inspecting each Cannula is time consuming and labor intensive. Therefore, the client was in great need to automate their system, as well as to achieve a false failure rate of 0%.

We combined Four In-Sight vision systems from Cognex with a combination of Spot and Backlight on different tracks to inspect the canualla. As there were number of gauges (sizes) running on the machine and as the inspection area was very small, we have gone with special Telecentric lens to avoid the parallax error while measurement.

To achieve our false failure rate of 0%, we introduced two methods of vision inspection. In order for each cannula to be indicated as “good,” it had to clear both inspection methods.

For the first inspection method, we used edge tools from Cognex Vision Tools software. This software was used to locate the bevel and check orientation is with acceptable limits. Once these conditions are satisfied then tools for checking heel length were enabled in order to optimize time. With this we were able to measure /inspect the heel distance as per customer requirement of 0.3mm from the bevel base.

We used histogram tools as our second inspection method. Histogram tools counts the number of pixels meeting certain requirements within a specific area. This allows the bevel to be located and inspected for any flaws such as breaks or holes on its surface.

Along with these two inspection methods, we introduced a way to reduce the glare. If glare is not reduced or eliminated, it can cause key features to be missed during the inspection process. To overcome this obstacle, we added a combination of filters on the captured image to make the variation more prominent for inspection.

The algorithm has been tested on both the Cognex In-Sight Micro 1100 and High Speed In-Sight 7400 vision system. The In-Sight 7400 enables a production speed of 75 parts/min.

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