When designing medical device components, you don’t need to choose between additive manufacturing and metal injection molding. Think of them as complementary.
Nick Eidem, Advanced Powder Products
[Metal-injection-molded parts image courtesy of Advanced Powder Products]
Metal injection molding (MIM) technology can efficiently and economically deliver thousands or millions of parts. Still, it relies upon custom-designed and built hard tooling — the simple reality of all MIM processors. As a result, medical device engineers frequently ask, “How do we capture the efficiency of MIM through the design and production validation stages? Is additive manufacturing the answer?”
While not to diminish the significant contributions and developments in additive manufacturing, some constraints still need addressing. Additive manufacturing may be the fastest way to get functional metal components, but the components are not production representative. Compared to production MIM components, the “grainy” or “granular” surface finishes and tolerance capability demonstrated by additive are inferior; it’s simply where the technology is today.
The choice between additive manufacturing and MIM is complementary. Medical design engineers and MIM manufacturers are applying their material expertise to binder-jet 3D printing technology. Binder-jet 3D printing is an additive manufacturing process using MIM powders and sintering furnaces to create 3D-printed functional MIM parts. A part generated via binder-jet 3D printing is not identical to a true metal injection molded part. However, many MIM processors utilize the technology to conduct processing experiments to shorten the development lead time while proving quick design iterations. The question remains, how do we bridge the gap between 3D metal printed prototypes and production tooling. The logical solution for the engineering and supply chain communities is to build prototype “hard” tooling that replicates actual MIM production components. Ultimately this allows for a shortened time to market without complicating the validation and regulatory process steps. The production-proof properties of MIM components produced via prototype tooling are a valuable solution to this conundrum.
The key to this is the concept of creating prototype tooling that can be designed, built and modified — producing MIM components in a more expedited fashion. While this seems like a “no brainer,” it isn’t as easy as one might initially imagine. Intuitively, the design community assumes that MIM tooling and plastic injection molding tooling, at least in the prototyping phase, are analogous. Designers sometimes think they can make the tooling out of a lower hardness specification material, maybe even aluminum. That assumption is inaccurate because of the abrasive nature of MIM powders, the turbulence characteristics of MIM powders under pressure, and the unique viscosities associated with MIM powders. Understanding the constraints of traditional tooling design provided MIM processors the impetus to research alternatives. Production tooling is designed to maximize efficiency and capability and often includes advanced technologies to monitor cycle times, feedstock flow and cavity pressure, which increases the time to build and speed to market.
Speed to market can be a significant constraint in the medical device market, resulting in pressure to consider alternative paths. MIM industry initiatives are evolving to create advances in prototype tooling alternatives, some cutting the time by as much as 50%. The natural segue for any metal injection molder is to drive changes in the tooling development process.
Developments in MIM prototyping inhabit today’s world of MIM and should be of serious consideration for the medical device industry. MIM prototyping can also generate immediate parts up into the thousands — a nice segue in launching any program or even modifying an existing MIM component situation. In addition, the costs basis is a fraction of production tooling, which gives the end-user an additional level of confidence in the development-to-production phase.
MIM is an exciting and developing new technology process that requires considerable collaboration between the medical device team and the processor. Collaborating with Advanced Powder Products (APP) offers a unique technology platform that includes prototype tooling, ProtoMIM, and other complementary additive manufacturing capabilities, even binder-jet.
To learn more about APP’s Rapid MIM Prototyping, visit advancedpowderproducts.com.
Nick Eidem is the director of business development for Advanced Powder Products. Nick has over 10 years of experience in manufacturing sales.
The opinions expressed in this blog post are the author’s only and do not necessarily reflect those of MedicalDesignandOutsourcing.com or its employees.
