The Challenge
A UK medical device manufacturer was developing an automated assembly line for a small ophthalmic surgical device used by surgeons during complex eye operations. Given what the device is used for, the tolerances involved were exceptionally tight. Components needed to be correctly oriented to a precision that left no room for ambiguity, and the assembly environment had to be verified completely free of dust and particle contamination at every stage.
Manual inspection was never a realistic option at this scale and tolerance. The only way to achieve the consistency, speed, and traceability the project demanded was a fully integrated machine vision system capable of checking orientation and cleanliness on every single part, every single cycle, with zero tolerance for error.
Duke Control Systems was brought in specifically for the vision system scope: capturing reference images, developing the inspection programs, and ensuring the system communicated correctly with the line's Siemens PLC, ahead of a customer Factory Acceptance Test (FAT) at a facility in the North of England.
The brief: Develop and commission a 9-camera Cognex vision inspection system capable of verifying correct part orientation and complete freedom from particle contamination on a small ophthalmic surgical device, fully integrated with the line's Siemens PLC, ready for customer FAT.
What Duke Did
Image Capture and Programming Across Nine Stations
The assembly line required vision inspection at nine separate points, each with its own Cognex camera and its own specific inspection task. Duke's engineers worked through each station individually, capturing reference images under production lighting conditions, and developing bespoke vision programs tuned to the exact part geometry and defect criteria at that stage of assembly.
Given the size of the components involved, this was demanding work. The device itself is small enough that even minor inconsistencies in lighting, part placement, or camera calibration could produce false readings. Achieving stable, repeatable results across nine stations required careful attention to lighting setup, camera positioning, and threshold tuning at every single one.
Orientation Verification
Correct orientation of components during assembly was non-negotiable. The vision system needed to verify, with complete confidence, that every part was correctly positioned and oriented before assembly proceeded. Duke's engineers developed and validated inspection logic capable of distinguishing correct orientation from any deviation, however small, ensuring incorrectly oriented parts were rejected automatically before they could progress further down the line.
Particle and Contamination Detection
Because the finished device is used directly during surgical procedures, freedom from dust and particle contamination was as critical as mechanical correctness. The vision system was configured to detect contamination at a level that would be invisible or easily missed by manual inspection, giving the manufacturer confidence that every unit leaving the line met the cleanliness standard required for a surgical product.
PLC Handshaking and Integration
Vision inspection only has value if it is properly integrated with the rest of the line. Duke's vision engineers worked closely with the project's Siemens PLC team to ensure the handshaking between each Cognex camera and the PLC was correctly implemented; pass and fail signals, station sequencing, and reject handling all needed to function reliably together. This close coordination between the vision and controls disciplines was essential to delivering a system that worked as a whole, not just as nine independent inspection points.
On a project like this there is no margin for "close enough." The device is going into an operating theatre. Every signal between every camera and the PLC has to be right, every time, and that only happens when the vision and controls teams are working from the same understanding of how the line behaves.
Working on a vision-critical assembly project?
Machine vision integration on high-precision or regulated products requires a different level of attention to detail. We are happy to talk through what your project would involve.
Start a Conversation →The Outcome
The completed vision system gave the manufacturer a fast, reliable, and fully automated way of verifying both orientation and cleanliness on every unit produced, removing dependence on manual inspection for a product where the consequences of an undetected defect were significant. The system was proven and ready ahead of the customer FAT, with Duke's engineers supporting the test itself to demonstrate the inspection logic and PLC integration performing as specified.
For the manufacturer, the result was a production process capable of consistently producing a small, precision surgical device at a level of accuracy and cleanliness that manual methods could not reliably match, with full traceability built into every inspection cycle.
At a Glance
- Sector: Life Sciences, Medical Device Manufacturing, North of England
- Scope: Cognex vision system image capture, programming and PLC integration
- Cameras: 9 Cognex vision stations
- PLC Platform: Siemens
- Inspection criteria: Component orientation accuracy and particle/contamination detection
- Application: Ophthalmic surgical device assembly
- Status: Complete. System proven ahead of and supported during customer FAT.