Vision system traceability in medical device manufacturing applications

Machine Vision solutions continue to be developed across a wider and more diverse range of markets than ever before. Much of the vision development continues to be driven by the Automotive industry but new areas of application are being opened in the field of pharmaceuticals. Traditional prerequisites for vision system installation can be applied to all industries, including communication and PLC control of the vision controller, multi tasking of the vision system and documentation of the vision procedure. This last point is clearly more needed in the pharmaceutical industry than any other where precisely defined check routine structures are needed and documented; especially within the constraints of CFR 21/210/211/GAMP validation.

Industrial Vision Systems Ltd have consciously designed the latest version
of their systems to include XML support to allow automated documentation to be created once procedures for automated visual inspection have been finalized. This documentation has been applied for the Pfeiffer company for the examination of pump bodies, similar to those found in nose sprays with a pumping atomizer. The developed machine for Pfeiffer was integrated by the applications department as a complete solution.The major inspection criteria for the system was the segregation of products against known measurement criteria to control quality of the final products. 

The solution consists of multiple inspection criteria. The first check involves examining the intermediate piston stroke length, an indicator for the piston stroke for the pump, in the range of tolerance of +-0.01mm. Based on this result a check routine is developed to distinguish between the five pump types available.

The second check involves examination of the transparent plastic body containing the spring and ball of the spray mechanism. Using a template matching function verification of these key components is completed. Typical errors contained in this area include double ball bearings, bent springs, misaligned springs and wrong intermediate piston.

Key to the application is incorporating the machine vision system into the machines cycle time, optimization of the template matching function using the unique automatic wizard meant the image processing could be contained within the necessary performance required.

The complete solution involved the pump bodies being fed on a rotary plate, thus the test position is well defined in terms of positional tolerance. Mounted in a fixed position, external to the carousel area are the 2 off NCG212 1296 x 966 digital cameras.

Once the pump body reaches the inspection station on the carousel the PLC sends a signal directly to the I/O control within the Industrial PC, evaluation by both cameras is completed and communicated back to the PLC within 100msecs. Each feature failure is indicated independently via single I.O. channels. Information is also stored in Excel with information exchanged to the offices via Ethernet connection.

As discussed previously documentation in the pharmaceutical industry is critical and once a complete solution has been finalized the complete inspection criteria can be automatically stored as an XML document as shown.

This gives detailed information on every inpsection function used and how it was set-up; this makes the whole system very powerful when deploying multiple systems across the pharmaceutical industry; and an ideal solution for Pfeiffer who require this sort of traceability.

The system is now reliably inspecting an annual production of 200 million pumps a year; with the knowledge that the software has been specifically designed to handle the detailed requirements the pharmaceutical industry demand.