According to 3D printing experts, 3D printing and injection molding each have their own benefits and limitations in regards to medical device parts, but 3D printing is becoming more and more adopted.

A medical 3D model that was used for reference during an operation. 3D Systems 3D printers an exclusive materials were used in the models to allow for selective coloration, showing surgeons what is hidden beneath layers of soft and hard tissue.

While 3D printing is increasingly being used for the production of medical devices over injection molding, additive manufacturing in the industry still has room to grow before it will completely replace injection molding in the manufacturing of medtech parts according to a panel of experts from this month’s Advanced Design and Manufacturing (AD&M) Expo held in Cleveland, Ohio.

The decision to use 3D printing or injection molding currently depends on what each specific customer’s – or patient’s – needs are said 3D printing industry experts at the show. These two processes can actually be used in harmony to provide the best overall solution. With 3D printing, users can get there parts in a mere fraction of the time that it would take to manufacture using injection molding methods. In addition to the increase in workflow speed, 3D printed components are also fully cutomizable and can be tailored to meet the needs of specific individuals. On the other hand, injection molding provides users the ability to mass-produce components – something very helpful for commonly needed/used medical parts and devices.

3D printing allows you to get parts in your hands very quickly without an investment in your tooling and it allows you to also [make] some parts that may not be necessarily designed for injection molding, but allows you to do geometries that are unique..I think it’s great when it’s not a part that’s actually injection moldable,” said John Budreau, director of new business at PTI Engineered Plastics.

A 3D printed, fully-customized cast that actually helps bones heal faster.

Members from the previously mentioned expert panel provided 3 limitations of 3D printing that will soon be overcome as the technology’s rapid development continues:

1. Machine Throughput

Thomas Davis, Protolabs’ Application Engineer, explained that there are some shortcoming in terms of machine throughput with 3D printing: “It’s traditionally a layering process. The layering process has mechanical properties that fall short from the isotropic standpoint. and the ‘Z’ when compared to the ‘X’ and ‘Y,'”

2. Tolerancing

Tolerance of 3D printed parts have seen many breakthroughs as of late (i.e. Markforged’s carbon-fiber reinforced 3D printing materials), but yet there is still room for improvement. “We’re pretty close to what injection molded parts can do, but [tolerancy] is still the biggest hiccup or disruption in our technology,” said Scott Kraemer, production development engineer at Carbon.

Markforged Carbon Fiber and Metal 3D Printing Systems are the future of manufacturing, dramatically cutting lead times and costs while producing parts up to 23 times stronger than standard 3D printed parts.

3. Material Options

With many materials now emerging, the 3D printing industry will undoubtedly breakdown many barriers limiting its uses in the near future. “Efficiency is going to increase, and once we can start using 3D printing more for production, I think that the materials will follow. There will be more material choices and colors, and it won’t be considered as niche and expensive,” Davis said.

“With injection molding, we’ll probably run 1,500 different engineered materials this year of everything you can imagine, whether it’s glass fillers or other content in the materials to achieve certain properties,” Budreau said. “Once the 3D printing world can do that with their properties, that’s when you can use the process for parts that are not injection moldable…It just depends on where [customer] product development needs are and where they’re at in the project. 3D printing really does serve a purpose for a lot of our production manufacturing process”

When to use 3D Printing over Injection Molding

As previously stated, the decision of whether to use 3D printing or injection molding or even both relies almost solely based upon the needs of each specific customer, but also depends on both the product development and quantity needs.

“Basically 3D printing is just another tool in the toolbox for the engineers to get their goals accomplished,” Davis said. “[Proto Labs] takes advantage of injection molding and 3D printing,” Davis said. “It just depends on what the goal is. The geometry — if it’s really complex, if it’s a high-value proposition part that is low volume — are great fits for 3D printing. If it’s not, higher quantities would be better for injection molding.”

Another factor which plays a key role in determining which process is best to use is the size of the components needs as platform/build sizes on 3D printers still remain limited to small sizes.

BigRep 3D Printers are designed for the production of large-scale parts and are breaking barriers in terms of how big things can be 3D printed

“You can only make x amount of parts. So, if you look at the size of a matchbox car and under, we can compete against injection molding in price range. When you start getting larger than that, it starts to get kind of where’s that balance that. When you start getting parts that are 6-by-6, somewhere around that range, that’s where it starts to lean little bit more towards injection molding,” Kraemer said.

It is also important to understand that each of these tools has its own limitations. Users will not always be able to injection mold a part that can be 3D printed, and vice versa. Because of this, it is important to have engineers with expertise in the technologies so they can best determine the process best suited for the job.

“Certainly 3D printing will take some of the injection molding market away, but I think the market will continue to grow,” Budreau said. “Honestly, it’s not necessarily a tipping point. It’s where you’re at in your project development process. What is the value of having an injection molded part versus a 3D printed part? Now certainly if the design is not injection moldable, that’s when you 3D print it.”

3D Systems 3D printers are used across a variety of medical applications.

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