3D Printing Methods for Medtech Prototypes

Being able to quickly produce prototype parts is critical to creating an environment of innovation that can lead to medical device market success. By removing inefficiencies, manufacturers should expect to have prototype parts in a few days, not months. The prototype method must be fast enough to allow multiple iterations in a condensed time frame, and possess the scale to allow for multiple iterations at the same time.

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Rapid manufacturing methods like 3D printing are leveraged to help drastically reduce development time for medical devices.

Additive manufacturing (AM), also called 3D printing, enables quick evaluation of new medical product designs without making compromises due to complex part geometries. Using AM offers easier design changes and at a low cost. When prototyping via 3D printing, designers should not expect a finished part, although it should be noted 3D printing processes can yield finalized products. Stereolithography, for example, has a number of post-secondary finishing processes and direct metal laser sintering produces fully dense end-use metal parts.

There may be limits to color and texture choices, and in certain instances, thermoplastic-like materials will differ from the final production material used in process like molding and machining. If the surface finish, texture, color and coefficient of friction vary from the end material, it is difficult to accurately assess the subtle needs and benefits of these properties.

The main advantage of 3D printing is that it provides accurate form and fit testing. The build process of additive technology can accurately produce the form and size of the desired part, making it very useful for early evaluation of new medical parts. It is best used to identify design flaws, make changes, and then make second-generation machined parts or invest in tooling to create injection-molded parts. This article reviews that various AM printing methods commonly used in prototyping.

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DESIGN TIP: Thermoplastic-like vs. Thermoplastic

Many factors come into play when comparing the material properties of thermoplastics found in injection molding versus “thermoplastic-like” materials used in a 3D printing technology like stereolithlography (SL). At Proto Labs, a thorough selection of thermoplastic-like materials are offered through SL, but what may surprise you is the versatility and range of potential applications for SL parts.

This month’s tip discusses:

  • heat deflection, tensile strength and other important properties of thermoplastic-like materials
  • how SL materials compare to similar injection-molded thermoplastics
  • the benefits and range of suitable applications for each SL material
  • the impact of light and moisture exposure on 3D-printed parts

READ THE FULL DESIGN TIP HERE.

Honey, I Shrunk the Pyramids: Met Museum, Proto Labs Create Model of Ancient Egypt

For the Metropolitan Museum of Art’s exhibition, “Ancient Egypt Transformed: The Middle Kingdom,” on view at the New York museum through Jan. 24, 2016, exhibit planners decided to reconstruct the pyramid complex of King Senwosret III in both a virtual and physical model.

The scale model of the pyramid site is displayed in the Metropolitan Museum of Art’s galleries.

The physical 1:150-scaled model of the site is based on a 3D virtual model that was produced first, and modeled after 3D-printed prototype parts that were created by Proto Labs. For perspective, the main pyramid of the original complex was more than 206-ft.high. In the scaled model, it is 1.5 feet. The creation of the model, which is intended to bring this important Middle Kingdom era to life for visitors to the exhibition, involved a process that was an intriguing blend of traditional and digital methods. This process included traditional sculpting, model-making, mold-making, casting, carpentry and faux painting, plus digital methods of fabrication, specifically 3D printing. The additive manufacturing process by Proto Labs served as the Met’s prototyping phase that helped replicate the unique parts of the model. Continue reading

EYE ON INNOVATION: New Balance Steps Up With 3D-Printed Customized Soles

We’ve blogged about sneaker technology in the past, highlighting Converse’s new Chuck II shoe.

Photo: New Balance

Now New Balance is stepping up with a new concept for a shoe that uses 3D-printed midsoles customized to an individual’s stride.

As Wired recently reported, most running shoes have midsoles that are resilient but are typically just a uniform piece of rubber foam. This foam doesn’t really account for the fact that every person’s foot impacts the ground differently, such as mid-strike runners or those who land on their heels first, etc. Researchers at New Balance are looking to make a midsole that’s “both resilient and smart.”

Photo: New Balance

The shoe company is working with Boston-based design studio Nervous System to create a 3D-printed midsole that can be customized based on an individual’s stride. Wired: “The goal is to extend customization beyond aesthetics, creating a shoe designed with biomechanical data that gives its wearer an optimized running experience.”

This 3D-printed footwear appears to be a trend. Companies such as Nike, Adidas and Jimmy Choo are increasingly exploring the applications of additive manufacturing in their design processes, creating everything from 3D-printed football cleats to 3D-printed haute couture shoes.

New Balance’s 3D-printed midsoles are “squishy,” lightweight and strong, and made of DuraForm Flex TPU, a proprietary elastomer.

Still early in the process, it is unclear if customized soles will actually improve the running experience, and help with elements such as reducing injuries, speeding recovery and enhancing overall endurance.

Eye on Innovation is a weekly look at new technology, products and scientific advancements that we’ve mined from crowdsourcing sites and other corners of the Internet.

TIPS WITH TONY: Can 3D-Printed Parts Take the Heat?

Here’s a question that’s often asked: How do materials used in 3D printing compare to injection-molded thermoplastics when the temperature rises? To answer that, I’ll briefly dissect the materials used in stereolithography (SL) and selective laser sintering (SLS) processes as these are commonly compared to injection molding.

Stereolithography
SL involves a thermoset resin that is solidified by an ultraviolet laser, followed by a UV post-curing process to completely solidify the resin. As far as material properties, the big takeaway is that SL parts are built from thermoplastic-like resins, so they do break down over time in direct UV light.

SL uses materials that mimic ABS, polypropylene and glass-filled polycarbonate, and they offer an array of material properties still exist. But today we’re concerned with the thermal properties of the materials that are best suited to handle the heat — 3D Systems Acura 5530 and DSM Somos NanoTool. Both are offered in post-cured states and there’s an additional process for thermal post-curing that increases the operating temperatures.

The chart shows optimal heat deflections for SL materials. The other materials offered in SL have a much lower heat deflection ranging from 120˚F to 177˚F.

Material

UV Post-Cure

UV Post-Cure +
Thermal Post-Cure

3D Systems
Accura 5530

85˚C (185˚F)

250˚C (482˚F)

DSM Somos NanoTool

225˚C (437˚F)

263˚C (506˚F)

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