Low-volume production often goes hand-in-hand with high costs, particularly if the variety of products is also extensive. For example, DePuy Spine, a Johnson and Johnson company based in Switzerland, produces small implants such as screws for spinal surgery. Previously, inspection had been done manually but, with regulations growing ever stricter, it became clear that only vision technology could provide the level of inspection necessary. Flexible part automation using a desktop robot, a Sony camera, and Cognex (Natick, MA, USA; www.cognex.com) software developed by its partner Compar proved more suitable and economical than fully automated in-line inspection.
In operation, each implant is placed in the cell of a blister pack. Each batch is identifiable by a code, and certain implant nests may be empty. The products are inspected in their individual nests by being passed through a desktop vision system.
The autonomous inspection system consists of a two-axis desktop robot and a PC-based vision system with the Cognex Vision Library as a platform. The camera is mounted on the desktop robot's y-axis, while the blister packs are moved along under the camera in the x-direction. Several inspections can be conducted for each nest.
To simplify the entry of data per batch, the system is equipped with a barcode scanner. The inspected data are compared against the set values and permissible tolerances. If a faulty product is detected, an alarm is triggered and quality-assurance personnel remove the product for manual inspection.
Advantages of the system include integration of vision in a mechanical environment allowing inspection of the whole batch at once; 100% inspection and quality control of medical implants before they are shipped; full traceability ensuring compliance; manual process made more efficient; and the camera need not be exactly positioned for results to be reliable. An additional advantage of the system is that it ensures full USA FDA 21 CFR part 11 compliance by tracking the results for each batch and integrating them for future reference.
Johann Faneca, production manager at DePuy Spine, says, "We are very pleased with the vision installation. Thanks to the automated solution from Cognex and Compar we estimate a saving in time alone of more than CHF 100,000 for the first year, which will be an excellent return on our investment."
Future plans for expansion of the application include surface inspection, print layout inspection, soldering point inspection, and code reading. The system is easily adaptable to many other types of inspection and identification applications.