Reliable, Single-Use Metal Components for Medical Devices—A Medtech Makers Q&A

By Sean Fenske, Editor-in-Chief
 
When someone thinks of single-use medical devices, the first material that typically comes to mind is plastic. Environmental impact, however, has become a greater factor in the sourcing of components for disposable healthcare products. As a result, medtech manufacturers are seeking alternative ideas with sustainability in mind.
 
One such option is the use of metal parts instead of plastic. While the immediate thought with metal is strength and durability, cost also often comes to mind. Fortunately, there are metal fabrication processes that leverage the strength of the material to make components that require less volume of metal as compared to plastic, thus positively impacting the expense.
 
To offer more insight on how metal can be used in place of plastic for certain single-use medical device components, Jon Mills, business development manager at Fotofab LLC, addressed a number of questions in the following Q&A. He covers inquiries around expense of metal, design considerations, working with service partners, and more.
 
Sean Fenske: Have you seen an increase in customers looking to develop single-use devices?
 
Jon Mills: I wouldn’t say we’ve seen an increase in single-use devices, but we have been working with more companies looking to replace components of their devices with more reliable single-use or replacement parts. It is expensive to redesign, test, and produce a completely new medical device, so we are working with design engineers to create new components to fit into an existing device. These components will often be a single-use surgical assistant that resides in the larger permanent device. For example, we have a customer who requires medical-grade metal snares assembled into an injection molded handle. The handle can be sanitized and reused, while the snare can be responsibly disposed of and recycled.
 
Fenske: Plastic seems to be the dominate choice when creating a single-use device. Why would metal be required?
 
Mills: Plastic has long been favored with single-use items across all industries and products. As we begin limiting our single-use plastic usage, metal is looked to as an environmentally sustainable option over plastic. Most of the medical device manufacturers we work with use a combination of both plastic and metal to produce a successful product. We are not recommending replacing all plastic with metal, although that would be great for business; instead, we are finding areas to strengthen a device with the combination. Sometimes that means metal components encapsulated by plastic to be inserted into a body, like a pacemaker, and other times, it means the metal comes in direct contact with the surgical area, like a cauterizer. Fotofab has experience working with hundreds of metals and alloys, including biocompatible options such as stainless steel and titanium.
 
Fenske: Isn’t metal expensive? Can that be a challenge with single-use device components?
 
Mills: A common thought about metal is that it is more expensive than plastic or other materials. While that may be the case with kitchen chairs and utensils, our process uniquely uses thin sheet metal to enable easy iterations and prototyping to get the part just right. In other words, engineers are not beholden to their first or even fortieth revision.
 
Since these parts are usually small, the amount of metal used—and therefore the price—is not as high. On average, we run 12 by 18 inch sheets; whether you fit two or 100,000 parts on that sheet, we don’t care. The complexity and feature size does not affect the price; only the number of sheets being processed changes the cost. Once the part dimensions are finalized, we increase the sheet amount run through our plant, smoothly transitioning to supplying mass production quantities while maintaining reliable quality and tolerances.
 
Fenske: What processes are used to fabricate single-use metal components? What are the advantages for each process?
 
Mills: I would separate the processes into two categories—the etching process and the value-add processes. First, the metal parts are manufactured using a photochemical machining process, also known as PCM, chemical etching, or wet etching. The benefits of PCM fabrication are speed, tight tolerances, burr-free finish, and no alteration to the physical properties of the metal. Fotofab uses a proprietary ferric acid etchant to remove unwanted sections of sheet metal, leaving an exact-to-print part. We do this in one or two passes through the machine so an entire geometry is created at once. We can manufacture never before seen parts in less than a day. As the acid etches away the unwanted metal, half-etched and through-hole features are formed at around 1.15 times the material thickness. Unlike laser cutting and stamping, the chemical etching process does not cause the metal any blunt trauma, leaving the physical properties of the final component identical from edge to edge.
 
The value-added processes include forming, plating, passivating, cleaning, plastic over mold, and bonding. Each has a unique value to add to the finished product and can assist in making the part more corrosion-resistant, and sterile, or increase the complexity of inner channels with diffusion bonding multiple layers together.
 
Fenske: The list of value-added processes seems quite extensive and requiring of different capabilities. Does Fotofab offer all of them or does a customer need to seek another company to provide some of the services?
 
Mills: Between our two facilities in Chicago, we offer photochemical etching and forming of parts. To satisfy our customers and serve as a one-stop shop, we work with our extensive list of long-vetted partners to get the rest accomplished before delivery. A notable distinction for us is we are part of a larger company called The Partner Companies (TPC). This network gives us access to leading manufacturers, including UPG—a complex plastic parts and assembly manufacturer. Going back to my example of the metal snare that is inserted into a plastic handle, our companies work together seamlessly to create the finished product for the customer. By having a close relationship with the TPC companies, we are able to cut time and cost.
 
Fenske: What are the important aspects of specifying metal components for single-use that device manufacturers overlook or fail to consider?
 
Mills: The main takeaway for all metal component manufacturing needs to be designing for the manufacturing process being used. Something we hear often is people don’t know what photochemical machining is, which is why our sales application engineers are so good at laying out the process and determining quickly what features or details need to be adjusted. As long as a developer shares the requirements for the project and knows what is and isn’t a must for success, we can gauge if our process is the best for the job. For instance, maybe we can tweak a corner to allow for a better bend or add a second process to enhance the end performance. It is also nice to have an idea of the production quantities so we can have metal and team support on hand for when you need us.
 
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?
 
Mills: Mainly to drive home the point that metal is a fast, highly precise, and inexpensive option when it comes to medical device components. Fotofab works with companies to create medical devices that are reliable and save lives. As mentioned before, we are able to work with hundreds of metal types and alloys. Whether you are looking for stainless steel 400s grade, titanium, or something more exotic, we are happy to have a conversation with you about the possibilities.
 
You are the medical device expert; we are the metal experts. Let’s work together and make Fotofab a part in your plan.
 
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