Medical Product prototypes are for the most part very similar to any other industry prototypes that we make here at Creative Mechanisms. We do however take medical product prototypes a step further than prototypes from other industries. We find that many of our medical device customers need us to provide a relatively small quantity of injection molded prototypes to use in FDA trials or consumer testing before actual production. The injection molded prototypes allow the customer to see how the product will perform in the actual molded material. A lot of the products that we engineer are small intricate plastic mechanisms. We often have snaps and integral springs or living hinges whose characteristics will change when the production method changes. In order to finalize a design we must take the Solidworks file as far as we can by evaluating the design using FDM prototypes. FDM stands for Fused Deposition Modeling which is our preferred technology of 3D printing. It builds parts by adding tiny drops of ABS plastic on top of each other to form a part from a file. After we are satisfied with the result of our 3D print we will make a prototype injection mold and evaluate the parts now that they have been made in the same material and using the same process as production. This evaluation will result in changes to the tool and the 3D file to bring the parts into the exact configuration needed for optimal performance.
It is a common assumption that injection molded tools are pretty much the same but there can be a wide range of quality levels for an injection mold. I divide injection molding tools into 3 general types. These types are prototype tools, production pilot tools and production tools. Within these categories there can be a wide range of quality levels depending on the materials used and the features added.
A prototype tool is a mold that is typically used to make several hundred up to a few thousand pieces. These parts are commonly used for consumer testing, sales samples or FDA trials. These parts are commonly used for consumer testing, sales samples or FDA trials
These molds are not necessarily built exactly like a production tool. I consider prototype production tolls a step between 3D printed prototypes and a production pilot mold. Prototype production tools are typically single cavity tools. We often use a hard aluminum if we can to reduce the cost and time it takes to build the mold. We will add features or actions in the tools that you might think would be reserved only for production tools. Sometimes though these features are necessary to produce the parts even though they are still considered prototypes. "Slides or Cams" are not uncommon if there is an undercut in the part that needs to be molded. These are special moving parts of the tool that allow areas that would normally be trapped in the tool to be ejected from the mold. We often use a Hot Runner (also called a Hot Sprue) to inject the plastic into the mold. This is a more advanced feature that costs extra but can be helpful in delivering a quality part if the part geometry and the plastic being molded could benefit from it. It also helps reduce the size of the runner or the plastic that flows through the mold before it gets to the part. If you are molding a very small part and you need to shoot a lot of parts in order to get the part design correct you can spend more in wasted runner plastic than the cost of the hot runner. We almost always use mold interlocks which keep the mold halves aligned and put less stress and wear on the molds guide pins. Some of these features can be eliminated if the quantity of parts needed is very low and the geometry of the part is fairly simple. Each job as to be evaluated so that the correct combination of mold quality and price is suitable for the intended use.
The next level of mold and the next step after a prototype mold would be a production pilot mold.
This mold would be used to make sure that the mold design is everything you want it to be before you proceed to the cost of a production mold with many cavities. Here you would use all the same material and features of the production mIn moving from the prototype mold to the pilot mold
you are moving from a focus on part design to a focus on production. The prototype mold was used to finalize the part design and get all of the design features working as desired in the production materials. The pilot mold and production mold are designed to make sure that you are replicating that part design but in high volume quantities.
Medical device product development benefits greatly from injection molding prototype tools. We have also built them for companies involved in packaging design where the design characteristics of a living hinge are best finalized through the evaluation of a prototype injection molded part. Could your products benefit from this process?