To find the right solution for the vision inspections, it was important to know the physical constraints of the production machine.
It was found, that it was only possible to fit the vision inspection in a part of the machine where the devices were moving at speeds of approximately 200 mm/s.
This had the consequence, that the shutter speed of the camera should be quite fast to avoid motion blur. Some motion blur is acceptable, but it complicates the image processing and reduces the sensitivity of the system.
When shortening the exposure time, the demand for light intensity increases. In this case, the demand for illumination was high. To find the correct combination of camera, lens, light, and timing, JLI vision made a replica of the machine setup, in their laboratory.
After some experimentation, this resulted in a setup where a sensor would trigger the camera and light source, at just the right time to get a picture. The engineers at JLI vision were confident that this would provide enough information to categorize the devices as either accepted or rejected.
Zealand Pharma also found, that one of the cylindrical parts in the devices could potentially have a break in its molding. It was important to know before it assembled with other parts in the machine.
The defects were not in a fixed position so pictures spanning the part’s entire circumference were needed to catch breaks.
To solve this, JLI vision developed a small box with a motor to rotate the part while light and camera were triggering at a high rate.
This solution ensured pictures from every angle. The pictures were then analyzed to determine if the part was fit for installation in the device.