By Sean Fenske, Editor-in-Chief
 
While molding is a well-understood and mature component fabrication technique, using new or unique materials can present unfamiliar conditions and challenges not all molders are familiar with. As such, when seeking to work with a specific material, it’s important to find a company that has successfully worked with it and made parts with it for the medical device space. This can sometimes, however, be easier said than done.
 
One such distinct material is liquid silicone. While there are a number of molders working with silicone, liquid silicone presents a completely different scenario for a part manufacturer. The raw version requires it to be handled and molded differently than traditional silicone. Finding a company who can provide the required level of expertise to develop components in this material is almost as challenging as the material itself.
 
Fortunately, IRP Medical provides such expertise and its General Manager, Trey Atkins, shared some of his knowledge in the following Q&A. Responding to questions about the material and how tooling for it can be an important aspect of the molding process, Atkins presents a number of significant considerations for medical device makers seeking to use liquid silicone.
 
Sean Fenske: In terms of molding, what challenges does liquid silicone present as a material choice?
 
Trey Atkins: Liquid silicones behave differently than plastic. First of all, it is a thermoset that requires a different molding technique and injection mold design. You need to vulcanize the silicone by heating up the mold and build a good liquid silicone injection tool with proper venting for the end of the fill. This will provide consistent material fill for every cavity with a very precise shut off to prevent parting line flash. As you may not know, silicone will pass through a clearance of 0.0002 inches.

 
Fenske: When it comes to molding with silicone, what considerations need to be kept in mind with regard to the tooling?
 
Atkins: Tool design is largely dependent upon the product design configuration and characteristics. Further, one must consider the number of cavities required to fulfill customer demand at various production stages, from prototyping, initial production build, scale up, through to full production. Complexity of tool design also relies upon the design choices made for critical surface areas, parting line locations, working or nonworking parting lines, surface finish, gating/fill locations, and many other factors.
 
IRP Medical provides all tool design choices suitable to the needs of every customer, from basic design to high cavitation fully automatic injection molding set up with in-line vision inspection capabilities and product removal.
 
Fenske: Can you please speak to what role the tooling plays when a manufacturer is seeking to upscale production volumes?
 
Atkins: The original tooling design is crucial in seeking to streamline a seamless upscaling of production volumes for any given project, starting with number of cavities selected, whether it will be a hot or cold runner, and provisions for tool/cavity insert replication. A successful and speedy new tool launch is dependent upon the precise execution of new tool design; build/fabrication; and the suitable match to an injection press/machine, robot, and automation systems.
 
Fenske: With liquid silicone, can tooling be leveraged to maintain high quality?
 
Atkins: Absolutely. The most robust and precise injection tool design can be leveraged to provide the most cost and quality effective option for a particular product using liquid silicone. While we are very familiar with all liquid silicones available in the market, we fully understand which one is the most suitable choice for every product application, knowing the material properties, performance, and most of all, its processability in injection molding.
 
Fenske: Is there any type of relationship between new tooling solutions and the challenges we’re seeing in the labor market?
 
Atkins: Yes, although not so much on the labor market, but rather, on the tooling expertise available in the global marketplace. For liquid silicones, there are only a handful of liquid injection mold makers out there that can deliver the highest level of tooling quality, which demands significant development time and results in higher tooling costs.
 
Fenske: Are there aspects of tooling you see often overlooked or misunderstood by manufacturers seeking to use liquid silicone?
 
Atkins: To this day, we feel liquid silicone is still misunderstood by many who claims they are experts in silicone. Too many molders and tool makers made attempts to perform liquid silicone injection molding and were not very successful. Our multiple decades of experience and expertise having been exposed from the very beginning of liquid silicone injection molding has given IRP Medical deep knowledge, including with specific applications. Our key people have been doing it even before rubber injection molding machines were sold off-the-shelves.
 
Fenske: Do you have any additional comments you’d like to share based on any of the topics we discussed or something you’d like to tell medical device manufacturers?
 
Atkins: Within our industry, we continue to share what IRP Medical can provide, which is critical-to-function elastomeric solutions for the medical device industry—particularly in custom liquid silicone injection molding and other rubber materials as well. We offer all choices available to solve molding challenges on medical components and devices—not just on silicones but beyond silicones as well.

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