Ever since I was a boy, I was fascinated by the idea of miniaturization. I read Isaac Asimov's Fantastic Voyage and then, when I finally got my hands on the movie, I probably watched it a dozen times. The premise was that a team of scientists were miniaturized to the point where they could be injected into a person and perform surgery from the inside.
Another movie with a similar premise was InnerSpace, starring the incredibly well-matched team of Martin Short and Dennis Quaid. There was the whole Honey, I Shrunk the Kids series of movies and TV shows, and I ate them up as well. Fast forwarding to present day, there's the Marvel Cinematic Universe and Ant Man, which also involved a teeny-tiny man doing amazing things at super-miniaturization level.
Part of what fascinated me was the idea that machines and gear, whether tiny ship or environmental suits, could be shrunk down to a level that traditional machining just couldn't go. For decades, the idea of producing components smaller than a human hair was nothing short of pure science fiction. But no longer.
In this article, we're going to chat with John Kawola, CEO Global, Boston Micro Fabrication (BMF), where we're going to talk about 3D printers that can actually produce parts that are fantastically small. If John's name is familiar to you, we met him two years ago when he was president of Ultimaker North America, a leading manufacturer of FDM (fused deposition modeling) 3D printers -- the filament-based 3D printers most people are familiar with.
Before we get started, keep in mind that a human hair is roughly 70 microns across. A white blood cell is about 25 microns across and a red blood cell is about 8 microns across.
Now prepare to be blown away.
David: Let's get started with the basics. Explain to your typical Ultimaker user, one familiar with FDM filament printing, what microscale 3D printing is.
John: As many people know, there are a number of different processes that fall under the umbrella of 3D printing. There is FDM, which is extrusion of plastic like Ultimaker. There is stereolithography (SLA), which is curing of photopolymer resin.
There is power bed fusion, which is sintering of powder, either polymer or metal. There are a few other processes as well.
Microscale 3D printing refers to the size of features and the tolerances that can be achieved. When we talk about microscale, we are referring to parts that have features below 50 microns [smaller than a human hair!!]. This is really not possible with FDM or powder bed fusion, but can be achieved with SLA technology.
David: Where does SLA printing with something like a FormLabs Form 3 end, and microscale begin?
John: SLA printing typically has optical resolution in the 30-100 micron range, meaning the smallest features they can produce would be above 100 microns. The BMF process, which we refer to as Projection Micro Stereolithography or PµSL (pulse), has optical resolution of 2 or 10 µm depending on the system.
This translates to getting features in the 10-50 micron scale [almost as small as a red blood cell]. Along with features, microscale printing yields very high surface quality (~1 µm rA) and dimensional tolerance (+/- 25 µm across larger dimensions).
David: What are the most common applications for microscale 3D printing?
John: The applications are the same as macro-parts: prototypes for form/fit/functional testing, tooling/jigs/fixtures and end-use parts.
Microscale printing also opens up industries that have been typically out of reach for traditional macro-scale additive. These are components like microfluidic chips and components, MEMS [micro-electro-mechanical systems] devices, microfilters, and RF waveguides.
The manufacturing processes that are disrupted in macro-scale additive are injection molding, machining and casting. With microscale, we are beginning to also disrupt micro-scale processes like photolithography, etching and swiss-machining.
David: Can you take us through some typical customer profiles for microscale printing?
John: Medical device manufacturers, drug discovery, electronics, high precision components.
David: So these are tiny prints. Can you make production (i.e., strong) parts, or are they really meant as delicate prototypes?
John: Prototyping is still a large application, but the materials are increasingly strong enough for end production.
David: Since these are tiny, presumably somewhat delicate objects, how do you safely remove them from the bed without breakage?
John: There are procedures for removing parts that eliminate breakage. The nature of the process also allows fewer or no support structures, which simplifies post-processing.
David: Are the chemicals used for printing toxic to the operator? Do you need PPE when using? And what about the final print? Can the final print be used against (or inside) the body?
John: The chemicals are similar to what is used in other SLA processes. Gloves are recommended for handling the resin and post-processing. There are biocompatible materials available. Currently, these materials are certified to 10993 standard for skin contact. Additional development is underway to enable implantable devices.
David: We saw some awesome applications of the Ultimaker machines in factories like VW. Take us inside a few customers of the BMF products and help us understand those workflows/work environments as it pertains to microscale printing.
John: One of the most compelling parts of micro 3D printing is that it is helping customers prototype and produce end parts that are typically much more difficult and/or expensive to make other ways. That is where the big value comes.
We are enabling prototyping capability where the customer previously couldn't make the prototype. We are enabling short run production where the current conventional method is very expensive. That is the big difference here.
Simple, larger plastic or metal parts that are easy and cheap to make don't really get the big benefit from additive. Additive adds the most value for parts that are complex, difficult and expensive to make.
Some medical device and microfluidic customers are now prototyping where they never could before. They had to accept the risk of going to production without the benefit of seeing physical prototypes. The production customers are utilizing micro 3D printing for short run early production runs (low thousands of parts), where molding is prohibitively expensive.
David: BMF is introducing new tech. Can you give us a quick overview?
John: The company started shipping our 100 series machines in 2018 and that has given us a good start. The S240 is our next generation.
The key differentiators are that it is larger, allowing production of larger single parts or more parts in each bed. We have also added a roller system to enable dynamic recoat of each layer.
This does two things: it significantly speeds up the machine, and two, it allows printing of a wider range of materials. More functional materials, including composites, are often thicker, having a higher viscosity. Static recoat of these materials was difficult on our 100 series. The roller eliminates that issue allowing use of resins with a viscosity up to 20,000 centipoise (CP)
David: Finally, share with us some of the coolest things you've seen printed with a microscale printer?
John: We have seen prototyping of glaucoma stents, parts that are less than 1 mm in size that are inserted into the eye for treatment of glaucoma. There is a large body of research developing 5G antennas for mobile phones. There is lots of energy around new immunization technologies, production of micro-needle patches for drug delivery.
Wow! I'd like to thank John once again for his time, as we travel into a future that seemed only possible in science fiction.
What applications can you see for microscale 3D printing? Let us know in the comments below. And here's a challenge: The first of you to name the Star Trek Deep Space Nine episode that shrunk Dax, O'Brien, and Bashir will earn bonus points and bragging rights for at least an hour.
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