Validation is a necessary step toward ensuring quality for the life of a medical device. As experts in injection molding validation, Team PTI can help reduce the time and costs associated with validation.
But here are some things for you to consider when validating your medical device…
Appropriate Material Selection and Part Design
Above all, medical devices must be reliable, and, through regulation (such as 21 CFR 820), the FDA plays a role in ensuring these devices meet reliability requirements. For manufacturers, this means following installation qualification (IQ), operational qualification (OQ), and performance qualification (PQ) guidelines, which serve to verify the equipment and the manufacturing process. Completing each of these phases ensures a process that will consistently meet design and quality requirements for the life of the product.
There are several key areas that are critical to consider before you begin validation activities.
Material Selection: Availability to Ensure Dependability
It is important to choose a material that is widely available in the market. Consider that if a material becomes unavailable (for whatever reason), you’ll be forced to either change suppliers or the material itself. Either way, you will be required to prove the new material is equivalent to your previous one. If you are unable to prove equivalency, validation will need to be reperformed and it’s possible the tool will need to be modified to make it compliant again.
For the same reasons, custom materials should be avoided. Furthermore, custom materials may also have higher amounts of viscosity variation. A higher amount of viscosity variation will make run-to-run performance less repeatable, require more adjustments, material scrap and decrease profitability.
Finally, its recommended that you do not make price a major factor in material selection. While material cost is a significant factor in the final cost, a 5- or 10-cent difference per pound is not substantial when compared to the $70,000 to $100,000 (or more) cost of completing a re-validation. It is important to take the time to evaluate the materials upfront.
Part Design: Going Back to the Basics
The principles of good plastic part design are also important to successful validation. These include adhering to uniform wall thickness, adding proper draft and limiting the amount of undercuts. In other words, the simpler the design, the higher the degree of reliability.
Most importantly, use a geometric dimensioning and tolerancing (GD&T) scheme that is realistic and does not require unnecessary and overly controlling criteria. For example, if only 10 critical dimensions are needed to fully define how a part is going to function, do not document more than that.
Also, if it is realistic to hold the dimension to only plus or minus .003 inches and not plus or minus .001 inches, then go with plus or minus .003 inches. This is easier to validate, gives a higher capability, and reduces the overall cost because it allows more flexibility within the desired specifications and has a bigger processing window during manufacturing. If critical dimensions are overly controlled, the process window for molding is smaller. The bigger the processing window, the more variation can be absorbed in the process. This leads to lower scrap levels, more uptime, and an overall lower cost for the product.
Mold Design and Construction
Other ways to limit the long-term costs of validation include using best practices for mold design and mold construction.
Mold Design and Construction: Be Selective Now to Avoid Issues Later
Mold design and construction are important to successful validation. Getting it right up front will help you avoid major issues later.
Mold construction should match your volume needs as well as the chosen material.
For instance, if you have corrosive materials, such as PVC, you should use stainless-steel inserts, so corrosion is limited. If you are using something abrasive, you want to have hardened S7 or H13 steel that is nickel-coated to make sure the cavity is not being eroded away by the glass that is compounded into the nylon. If you intend to use the mold to manufacture millions of parts, you must make sure you select materials that can withstand 20 years of production versus only two months. If you use a subpar material, you may have to replace it three or four times, which may not be beneficial for your overall validation costs in the future.
Utilize Simulation for Mold Design
Mold flow analysis can be a valuable tool for mold design. This allows the mold designer to identify and eliminate problem areas before they happen. For instance, if the part design has a thick area, the designer can see variable temperature distribution on the part and will design better cooling for that area. The designer can also use simulation to find air traps in a blind pocket. They can then put in vent pins or use a porous steel to help eliminate the gas. The insight found during simulation allows better decisions to be made up front to avoid issues on the back end.
Conclusion
Proper material selection, part design and mold design and construction for new medical devices is imperative, as they all can have a major impact on manufacturability, time to market, and the overall commercial success of the device. The above criteria are just a small portion of everything you must consider.
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Learn about the 12 things that will delay your molding validation: https://info.teampti.com/plastic-part-validation
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