This segment picks up where we left off in this video series discussing how not all manufacturing processes are ideal candidates to be replaced directly with 3D printing. We want to demonstrate that the 3D printing process can still have a significant role in bringing those products to market.
In the previous videos, I designed and 3D printed several iterations of a rear thermoformed wing for a radio-controlled 4WD race buggy using SOLIDWORKS and Stratasys FDM printers. At the end of the second video, I converted the wing design into a two-up thermoforming tool. In this video, I will 3D print the tool design and use the traditional process of thermoforming sheet polycarbonate to make our end-use parts. Finally, we will take some samples to the race track and see how they perform.
This journey to end-use parts starts in West Virginia’s capital city – Charleston. West Virginia is home to an amazing series of advanced manufacturing technology centers known as the Robert C. Byrd Institute (RCBI). They are a TriMech client and were more than gracious enough to help me with the production of both parts of this project.
3D Printing the Tooling
RCBI has 3 locations. Each houses an impressive list of manufacturing processes. All this horsepower is used to provide contract manufacturing, innovation, and workforce training for area businesses. The South Charleston location has capabilities that include water-jetting, milling, turning, 3D scanning, and additive manufacturing (including FDM, full-colour PolyJet, and metals). I try to visit our friends at RCBI whenever I’m in the area to talk shop, but this go-round I had a specific request for them – I needed to use their Stratasys F900.
The Stratasys (Fortus) F900 is a large format FDM printer that is capable of printing high-performance plastics such as Polycarbonate, Nylons, and Ultem. For this tooling application, ULTEM 9085 was a perfect fit for producing this project’s thermoforming tool.
While the print size of the Fortus 900 may have been overkill for this relatively small tool, its ability to accurately produce parts using extremely high-temperature materials made it ideal. Since we desire to pull a vacuum through our tool, we elected to print the part using GrabCAD Print standard “Sparse – Double Dense” settings to make a tool that had porosity to it. ULTEM 9085’s ability to withstand high compressive pressures at elevated temperatures would help serve our tool well in preventing it from deforming during thermoforming.
Not 3D Printing Our End-Use Part
Heading up the road to RCBI’s Huntington location gained me access to a different set of tools. Here you can find a wide range of machining tools, many used for workforce training, along with injection molding, laser cutting, additional polymer 3D printing (including Stratasys FDM), and thermoforming. The latter of which is our focus on this visit.
Thermoforming, sometimes called vacuum forming, works on the simple concept of heating a thin sheet of plastic until it becomes extremely soft and then using vacuum pressure to pull the softened plastic sheet around an object so that it takes the form of that object after the sheet cools. In this case, that object is the Ultem 9085 tool we produced in Charleston (which is shaped to produce two RC wings at once).
Our first task was clamping a sheet of .030” polycarbonate in the machine’s sliding frame to warm it up. Once the sheet is soft and begins to sag in the frame, the frame is slid out from underneath the heaters and positioned overtop the Ultem thermoforming tool. The tool is then simultaneously pushed upwards into the softened sheet of polycarbonate while a vacuum system turns on and draws all the air out from around the tool. This vacuum pulls the polycarbonate tightly around the tool and picks up even the faintest of details.
We pulled about ten sheets of polycarbonate on the tool. While I did not bring an infrared thermometer to monitor tool temperature, it became untouchably hot after a handful of pulls. As expected though, the Ultem 9085 tool did not show any signs of wear or deformation thanks to the material’s excellent high-temperature performance. While everything was warmed up and going, we went ahead and did two pulls using sheets of 3mm Acrylic-Polyvinyl Chloride (IPK) with a faux carbon fiber weave. IPK is an extremely tough material, commonly used in military and law enforcement weapon holsters. It was interesting that while this was a substantially thicker gauge material to the polycarbonate, it drew tighter into the tool and held more detail in tight corners.
End-Use Part Testing
Once I got back home from RCBI, I got to trimming out the polycarbonate wings and fitting them to the buggy. As expected, they fit nicely with no clearance issues (unlike my first iteration which you can see in part 2). With the new wing looking so nice, I had to make sure the rest of the car looked the part, so I painted up a pair of bodies for the occasion – one in a TriMech livery and one to show some love to my friends at RCBI for all of their help.
With everything finished up, it was time to see the end result in action. I went over to my local RC track, Adrenaline RC in Winchester, VA where they were nice enough to let us put some laps down after hours when we could have the place to ourselves. In the end, the wings performed great, and as expected, held up to several high-speed tumbles. In an unexpected turn of events, a local driver used one of the wings for a club race and ended up taking first place with it the very next weekend!
So, while 3D printing is an amazing tool that is tackling more and more problems each day, we wanted to highlight that there are still many applications where it is not (yet) the best fit. We focused on a thermoformed feature on an RC car as our example, but there are many other applications out there that exhibit the same scenario of a low-cost traditional manufacturing process that can produce parts with superior performance characteristics that are hard to beat. All is not lost, though, for 3D printing in these instances. As we illustrated, there are many areas where 3D printing can still be leveraged. This includes prototyping, manufacturing aids, and tooling. While not end-use parts, the use of 3D printing greatly reduces the time and cost of getting to end-use parts.
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