For all the talk about mass production in additive manufacturing (AM) and the possibilities for full three-dimensional design control, there’s a lot less focus on that thorny fourth dimension: time. And time is directly related to one of the most pressing issues in the industry—thermal management.
Within the last 10 years, the proliferation of area-wide printing methods has pushed productivity to new levels. Many companies found that fusing or curing an entire layer at once gave them a first-principles advantage in speed, and an improvement in consistency across a layer. This evolution cracked open the door for more mass production of end-use parts.
But mass production isn’t just a speed race. Together with larger production runs comes the requirement of even tighter process control. For plastics, that means controlling thermal variation across the build area, as well as against time itself.
For lessons in thermal management, we can look to the injection-molding industry. The unseen heroes that give injection molding machines their incredible productivity are cooling lines wrapped through the tool to make sure every part has the exact same thermal experience. Without them, internal heat would build, material properties would change, and defects would rise. The inevitable result: A forced slowdown, running the process at a fraction of the speed it is capable of achieving.
That’s the situation many 3D-printing companies find themselves in today. When screens replaced lasers, the new speed barrier became the management of heat buildup. Temperature control in production is most vital where the printing and networking of polymers occurs—in this case, where ultraviolet energy reaches the resin. This is also where the heat from the reaction is released.
For many 3D printers, slowing down became necessary to maintain control, giving up newfound productivity gains. The larger the build area, the more pronounced the problem.
The best ideas are often borrowed, and the decades of improvement in traditional manufacturing tell us that moving faster requires active heat management. While it is not the only engineering challenge to solve in the realm of AM, it can confidently be listed as a necessary capability to push size, speed, and consistency to the next level of productivity for plastics production.
It was this reality that led to Azul 3D Inc.’s High Area Rapid Printing (HARP) technology. Announced in the journal “Science,” HARP is a new printing process where the liquid resin floats directly on top of (but doesn’t interact with) an optically transparent, chemically inert, and constantly flowing layer of cooling oil. This oil layer absorbs heat from the reaction right where it is produced and carries it out of the system, without ever interfering with the digital light source. The result is a stable build temperature no matter how large, high, or fast you go. It’s an elegant answer to a fundamental problem.
As 3D-printing materials improve, opening the door for more production applications, we may see thermal management becoming the topic du jour. Hopefully, as with injection molding, innovative solutions to fundamental physics can unlock new doors and bring us to the next epoch of high-volume production.
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