A 3D metal printing process in operation using a laser. While lasers themselves are not hot, the heat produced when the photons make contact with metals can be significant. (Photo courtesy GE Aerospace/Armour & Associates)
GE Aerospace looks to engineered plastic cooling towers to expel heat from its laser powder bed fusion 3D printing process.
PICKERINGTON, Ohio—Additive Manufacturing (AM) is booming. According to a recent report from Persistence Market Research, the sector is currently on pace to grow by more than 22 percent this year and is expected to double in size by 2028, exceeding $15 billion.
Traditionally, additive manufacturing, also referred to as 3D printing, consisted of turning plastic resins into prototypes and low-volume parts. Now, the industry is expanding to include a growing list of metals that can be processed on sophisticated 3D printers. However, along with these advances comes a new challenge: managing excessive heat loads.
The use of plastics in additive manufacturing requires relatively low temperatures, often under 300 degrees Celsius. With metal, however, the print media can reach temperatures ranging from 1,100 degrees C to 1,400 degrees C. To mitigate the heat, cooling towers are increasingly being employed to cool the process water down.
This is exactly the challenge that the GE Aerospace additive manufacturing facility in West Chester, Ohio, recently encountered.
“The aviation company was working on a state-of-the-art approach to manufacture metal aircraft parts utilizing laser 3D printers,” said Steve Coppock, consulting engineer at Armour & Associates. The Ohio-based company provides for the design, installation, and commissioning of both HVAC and processing cooling systems. “The engineering firm brought us in to help with the cooling system that was required to chill the water used in the processing of these parts.”
The Delta cooling towers are made of the engineering plastic, high-density polyethylene, or HDPE. (Photo courtesy GE Aerospace/Armour & Associates)
Hydrodynamics
From light-weight designs, rapid prototyping, and now increasingly used for low- to medium-volume components, additive manufacturing is still in a fledgling state with an incredible amount of untapped potential.
At the GE Aerospace facility, which has been the focus of important R&D work for the company, the laser printers are used for components that require complex geometries or exceptional precision. While lasers themselves are not hot, the heat produced when the photons make contact with metals can be significant.
“The facility was looking for a cooling tower that would provide some longevity and would not require a lot of maintenance or repairs,” explained Coppock. “We had been having a lot of success with cooling towers made out of engineered plastic and recommended them for this application.”
Made of high-density polyethylene (HDPE), engineered plastic cooling towers are corrosion-proof, offer exceptional durability, and require significantly less maintenance, as well as an easier and quicker installation.
Launch window
The first tower at the GE Aerospace facility was installed in late 2022 and, after a successful debut, a second tower was added a year later to increase production.
“The Delta Cooling towers have been a good fit for this facility, and with the 20-year warranty, they are covered for the next two decades,” said Coppock.
Delta Cooling Towers pioneered the engineered plastic cooling tower design in the 1970s. The seamless one-piece shell has no joints, seams, panels, gaskets, bolts, fasteners or caulking like conventional towers. The models selected were the Paragon series, which each have a cooling capacity of 250 tons.
“They really appreciate that the towers are environmentally friendly as well,” said Coppock. “They don’t require as much water treatment chemicals, you lose less water from drift, and your energy savings can be significant.”
Increase in altitude
Another issue for any end user looking to add or replace a cooling tower system is the potential noise it generates. At the GE Aerospace plant, the towers are between two buildings, which could have created a significant echo reverberating throughout the industrial park.
To combat the issue of noise, the engineering firm decided it would be best to elevate the towers so that they sit closer to the roofline of the buildings.
“The towers look great sitting up on those platforms, but in hindsight, we may not have even needed to raise them up above ground level because they run whisper quit,” explained Coppock. “When you’re standing there, literally, the only thing you hear is the water running through.”
The towers also came with variable frequency drives (VFD), which allows the fan speed to vary so that the units do not run at maximum RPM except when necessary. Depending on the application, this alone can result in significant energy savings. An independent report by the New York Power Authority estimated almost a 40 percent decrease in electrical consumption when using the VFDs on Delta’s cooling towers.
Installation at hypersonic speed
High-density polyethylene (HDPE) cooling towers can deliver additional cost-saving benefits with a quicker, simplified installation. While getting a typical cooling tower up and running can take several weeks or more, the engineered plastic designs are factory assembled, enabling an installation process that can often be completed in as little as a single day with a smaller crew.
“That installation was basically plug and play,” said Coppock. “Don’t get me wrong, there’s some wiring and piping to do, but nowhere near the scale that it takes to put in a stainless steel, galvanized, or even a fiberglass tower for that matter.”
The savings did not end there for GE Aerospace. Coppock estimated that the two new cooling towers have greatly reduced the company’s expenses on costly water treatment chemicals. And because they are being well maintained, they have essentially eliminated downtime related to processing temperatures.
“They are getting about a 10-degree Delta T from these cooling towers and that is more than enough for them to be able to maintain their production on these laser printers,” said Coppock. “I would say everything has been running seamlessly, which allows us to move on to our next job without having to look back.”