As flexible manufacturing becomes a more attractive option to medical device manufacturers, ensuring that the processes involved with it all work in sync is critical. With leak testing in this system, there are a number of factors that need to be considered. This article reviews the areas that engineers need to keep in mind when adapting to this option.
Flexible manufacturing is a strong force in the medical device industry and requires new approaches in leak testing systems. Technology, such as rapid prototyping, has evolved that allows manufacturers to launch new products more often. Part design moves fast from CAD to production to distribution. It is a digital manufacturing world fueled by intelligent automation, and testing must adapt to the influences of this trend.
If there was a compass for how leak testing should work with flexible manufacturing, north, south, east, and west would point toward specific areas of good manufacturing practices. Look for these four points when considering leak testing equipment for medical devices:
- Modular, error-proof design for quick-change fixtures and instruments
- Optimization for fast throughput, short runs, and expansive part variety
- Ethernet capable, network ready with ability to change and customize test sequences
- Quality control technology for current and future products
Modular Design and Quick-Change Fixtures
Quality engineers responsible for numerous parts need leak testing systems that are modular in design and error-proof in nature. By extension, they need quick and easy part changeover. Fixtures must be simple to use with plug-and-play design. Most importantly, though, the system must work only when the combination of part and fixture is exactly right for any given test parameters.
Poka-yoke considerations exist specifically to protect operators from self-inflicted errors. As parts and tests are changed, conditions are set to ensure a correct match between fixtures, parts, and programs.
A few things to keep in mind about fixture design:
- Fixture design is a key factor in cost control and accuracy.
- Jigs and fixtures are very important and COTS (commercial off the shelf) items are not usually good enough.
- Beware of physical dislocation of seals between testing instrument and component being tested (seal creep).
- Beware of excessive clamping force (it masks leaks).
Fixture design is so important it can make or break testing. An inability to tell the difference between good and bad parts can sometimes be traced to faulty testing methods, which are usually caused by inadequate understanding of real testing requirements (creep, masking, fixture design). These considerations are not usually second nature to production engineers, so it is best to use testing experts to design fixtures. In the end, time and money are saved on testing systems that work right from the beginning.
Optimization for Fast Throughput, Short Runs, and Part Variety
Versatility and optimal leak testing requires streamlined systems. Intuitive touch screens and selectable I/O ports make it easy to add, edit, and change programs and part parameters. Best-in-class, web-enabled instruments allow pressure limits and fill times, upper and lower calibration factors, and many other variables to be controlled remotely. As production runs compress and part variety increases, throughput accelerates with easy-to-use, built-in options for control and customization.
When flexible manufacturing is crucial, then the fewer test instruments there are in the lab, the better it is for capital expense, floor space, and user training. Quality engineers naturally prefer a single instrument that is versatile enough to measure leaks from just a few sccm to several hundred sccm even as part volume fluctuates from very low to very high. New technology is available that allows testing with one instrument that does the job of many. Investigate these options early.
Ethernet Capable; Network Ready
The customer data highway continues to grow as more equipment plugs into the plant network. Some of this is driven by FDA regulations, such as strict requirements for traceability. Look for three key network features on leak test equipment:
- Compare network specs (BUS compatibility) and bandwidth so huge datasets along plant-wide networks can be transmitted.
- Check for internet-based remote diagnostics so production line inefficiencies can be reduced.
- Confirm available interface for barcode scanners to ensure compliance with traceability measures.
Quality Control Technology for Current and Future Products
Flexible manufacturing is possible thanks to many technologies. Robots often are part of the production landscape because they improve cycle time and can be reprogrammed for new parts. Ethernet and built-in web capability enables data transfer and remote diagnostics, which enhances quality control. Barcode scanners are essential for FDA compliance on traceability. Best-in-class leak testing technology is modular, fail-safe, and integrates with all these tools, which gives it the longevity to be used on products not yet launched.
Capital investments that last beyond the life cycle of current products are good for business. Here are some important factors to consider when planning for long-term return on investment from leak testing systems:
- How automated is the assembly and test operation (including specific testing stations)?
- Are there ergonomic issues? (Even manual operations can be optimized.)
- Do you use poka-yoke to avoid testing wrong parts? (With best-in-class testing equipment, only parts with correct dimensions are tested in a fixture designed with poka-yoke design.)
- Software is important and COTS is not always cheapest or best suited. (Beware of “bloatware” and limitations for data handling of important application parameters. Commercial off-the-shelf software often is not good for real-time information—instead, it may only provide test cycle times and not current traces of the test instrument transducer.)
- COTS software will usually miss the mark for calculating R&R percentages based on number of trials performed.(This problem is solved through test-centric assembly design.*)
- Do you want to save money with leak detectors that operate as standalone instruments and can interface with a PLC or PC by various methods, including Ethernet control (IP/TCP)?
- Are the quality system designers experts on testing who have solved an array of leak-testing challenges?
Testing expertise is the most critical factor to consider when developing quality control systems, and it is one of the most commonly overlooked issues by medical device manufacturers. There is no way to replace the knowledge base of testing engineers dedicated to the design, customization, and calibration of leak testers. In the end, that flexible manufacturing compass should point toward reliable, experienced experts for leak testing solutions that deliver promised performance.
*Gage R&R of an entire assembly and test solution is what counts—not just specifications from the manufacturer of a test instrument. This is test-centric focus. It is why application engineers whose sole focus on testing is crucial to project development teams. Nothing is trivial.
For more information, visit http://www.intertechdevelopment.com/2010/test-centric-assembly/.