Vision systems enhance medical device quality

Today’s Medical Developments (TMD): What advantages do vision systems bring to manufacturers of medical devices, equipment?

C. W. Moran (CW): As medical manufacturing increases in complexity, accurate measurement and inspection become increasingly important. The biggest advantages of a modern vision system are the sheer flexibility and customization options that suit the ever-increasing and demanding needs of medical manufacturers. Users can choose from tabletop microscopes, horizontal and/or vertical view tabletop systems, as well as floor-standing models in horizontal or vertical viewing orientation. All systems can be customized with zoom or telecentric lens options and some systems, such as the Starrett AVX550, offer dual optical inputs for the best of both worlds. Added features such as lighting control, touch probe capability, rotary indexers, and other accessories allow modern vision systems to provide nearly limitless application capabilities.

TMD: How is inspection accuracy increased with touch probe capability?

CW: Touch probe capability increases the accuracy of vision systems by providing an additional layer of inspection. Discrete points that can be hard to reach, such as bore holes, can be accurately measured with the touch probe sensor by traveling into recessed spaces and taking the required measurements directly.

TMD: Medical devices and equipment often have intricate, three-dimensional shapes, so how do image- based vision systems that inherently measure in two dimensions adhere to quality standards?

CW: For most modern vision systems, taking measurement points in the Z-axis is a standard feature or offered as an option. When combined with high-magnification optics, the system can capture numerous, accurate data points in all three dimensions. Touch probes or laser sensors can add an additional layer of inspection capability, allowing for the capture of discrete points on a part’s profile to be built into the inspection process as programmable steps.

TMD: How has improved resolution and speed enhanced the field of view (FOV) for intricate part inspection?

CW: Intricate parts often present unique inspection challenges. Customizable camera solutions have been developed to handle these challenges. Zoom lenses can produce up to 310x magnification on the monitor. Telecentric optics come in a wide array of lens options; 0.14x to 4.00x. Systems such as the Starrett AVX550 can be equipped with telecentric and zoom optics. This allows intricate part details and larger features to be inspected without changing lenses or recalibrating. The Starrett AVR-FOV comes equipped with a dedicated 2.3" x 1.9" FOV; the largest available to date for Starrett. Combined with integrated stage motion, these camera systems can also stitch together multiple images sequentially to create one larger image, allowing more of the part to be viewed at one time.

TMD: What role does light play in vision systems, considering the reflective nature of some materials used to produce medical devices/equipment?

CW: Proper light control is crucial for accurate in-process measurement to ensure that highly reflective surfaces found on many medical devices do not interfere with obtaining accurate results. All lighting systems on vision systems can be adjusted for intensity, depending on the specific needs for measuring the part feature. For repeatable and reliable results, light levels can be integrated into the inspection process as programmable steps. This ensures that enough light is present to illuminate the feature without washing it out and distorting the image.

TMD: What role does part orientation play in ensuring success using vision inspection with medical devices/equipment?

CW: With modern vision systems, and their integrated software, part recognition profiles can be created based upon a few key points on a component’s profile. Once this profile has been created, another part, or multiple parts, can be placed in the camera’s FOV to initiate the part recognition profile. The camera will orient the part based on the key points and automatically run the preferred measurements, generating a report in seconds. Additionally, accessories are available that assist with proper part orientation such as fixtures, vises, and rotary indexers.

TMD: What type of repeatability, reliability do vision systems bring compared to manual inspection processes?

CW: With the advent of part recognition programs, vision systems now boast an extremely high level of confidence in repeatability and reliability. Additional features such as touch probe capability and video edge detection, which detects transitions between light and dark fields, further help guarantee accuracy by eliminating operator or operator-to-operator subjectivity. This user-friendly process, known as walk-up metrology, means that once a part profile is created, any employee can initiate the program and

TMD: How does a vision system assist in inspecting medical devices throughout manufacturing (i.e., the ability to inspect at various stages throughout manufacturing for verification of all steps)?

CW: Vision systems are crucial to minimizing waste and saving time and money throughout the manufacturing process. Quick inspection checks are often used in-process to determine that design specifications are being met. Tolerancing can be used to confirm that intricate features are being produced accurately, within an acceptable range. Touch probes ensure bore holes are accurate and can also help determine when a cutting tool is falling out of spec and needs replacement. When placed in a walk-up metrology scenario, often directly on the shop floor, vision systems can be used by virtually any employee involved in a manufacturing process to perform an inspection check. Errors can be caught in real time and adjusted in-process, so that the finished product is right the first time, preventing costly rework or scrap.

TMD: Medical devices/equipment are often manufactured for years using a process that cannot change without regulatory approval. Why should a company using touch probes for medical device/equipment inspection consider a vision system and what challenges/opportunities would they face?

CW: Adding a vision system into a company’s inspection process will only increase confidence in manufacturing parts. Most vision systems are touch probe compatible, so manufacturers can continue to measure discrete points on a part’s profile, while adding measurement capabilities for a range of applications.