3D printed lattice structures can be made to have foam-like characteristics. These structures are branded “Digital Foam” by EOS. They represent a new opportunity to engineer better, safer, more customized and higher-performance products in a variety of industries.
However, designing 3D printed foams is challenging. There are myriad variables controlling the performance and function of a 3D printed lattice structure, including the size, shape, and direction of the struts, the geometry of voids, the material, and more. This means that engineering a digital foam can be very expensive and time-consuming.
Overcoming these difficulties is why industrial 3D solution provider EOS has put together a comprehensive package called the Digital Foam Program – In partnership with CAD firm nTopology, the EOS Additive Minds applied technology team makes the CAD process, the material selection and adoption, part qualification and additive manufacturing of 3D printed foam easier. The aim is to simplify the engineering and analysis required to create 3D printed foams, therefore accelerating the application of additive manufacturing to make better products.
“We can replicate and outperform most conventional foams out there. Using elastomeric materials like the thermoplastic urethane (TPU) or polyether block amide (PEBA) we can replace ethylene-vinyl acetate copolymer (EVA) style foams. Using a high impact strength polyamide like PA11 for the Digital Foam, it would be a replacement for acrylonitrile butadiene styrene (ABS) foam, like in a bike helmet, for example,” explained Fabian Krauss, Global Business Development Manager at EOS North America.
What Are the Benefits of 3D Printed Foams?
Polymer foams, including open-cell and closed-cell formulations, are used for a variety of applications across multiple industries including consumer goods, such as footwear and sports equipment, as well as aerospace and automotive. Foams of different densities and elasticities are used for different applications, such as support and comfort, energy absorption and energy return.
As Krauss explained, a 3D printed foam can have different zones of stiffness and softness throughout a continuous 3D structure. This creates opportunities for customization, which is ideal for products like sports equipment or automotive interiors. Because it’s additively manufactured, that complexity does not add cost to the manufacturing process.
Different foam applications have different use cases. For example, the foam used in a protective helmet would typically be stiffer, such as expanded polystyrene foam. A foam used in a running shoe could be selected for energy return and elasticity at an extremely low weight. With Digital Foam, all these different desirable foam characteristics can be designed into one single part, printed of one material.
Furthermore, because different foams have different properties, many products are an assembly of multiple layers of foams to achieve the desired performance. As creating the optimal assembly would be costly and increases the complexity of the supply chain, sub-optimal material combinations are often used to meet cost targets – compromising performance.
“Using 3D printed digital foam reduces the supply chain complexity significantly. For example, Aetrex has employed EOS’ Digital Foam to design premium comfort insoles,” said Krauss. “It used to be three different layers of foam: one to provide the support, another one to kind of absorb the pressure and then a third layer, which provides the comfort and the nice touch and feel.”
Using a 3D printed digital foam, “It is just one foam, which has stiffer and softer areas within it because it’s digitally tuned for that. This has reduced assembly times and the complexity of the supply chain.”
“The third benefit is in reducing waste and making products more sustainable. If you make everything out of one material, you can fully recycle it. For example, you could shred an entire product and recycle it and start the process all over again. When you glue three different types of foam together, all you’re creating is at some point landfill, because you can’t really recycle it anymore. By tuning the characteristics of various kinds of foam into one part and with one material, we’re also improving the environmental impact.”
Aside from sports equipment, footwear, and other consumer goods, digital foams have several applications in the automotive industry.
“I think customization for supercars is one interesting potential application for customization,” said John Walker, Business Development Manager at EOS North America. “Imagine, before you go buy your new supercar, you go sit on a pressure sensor. You can be 200 pounds, 300 pounds or 150 pounds and everybody has a different posture, everybody’s going to sit in the seat differently. Imagine having a perfectly tuned race car seat specifically for your body in your new supercar. That could be a shorter-term use of Digital Foam in automotive before it fully scales into some of the more popular, mass-produced vehicles.”
In addition, dashboard parts have historically used technology such as TPU over-moulding and sprayed foam coatings for safety and comfort. Nearly the entire interior of a vehicle—from the seats to the roof lining to the steering wheel and dashboard—uses foams and other soft materials. With a faster, more predictable and more cost-effective way to design digital foams, automotive OEMs can more easily test and experiment with additive technology in these applications.
What Are the Challenges of Engineering 3D Printed Foams Without the Digital Foam Program?
Complex lattice structures have long been a key strength of additive manufacturing. As more flexible materials have entered the additive materials market, compliant and deformable structures have become possible alternatives to conventionally manufactured foams. However, designing these structures requires a large base of design, materials and additive manufacturing experience and expertise. With the Digital Foam program, EOS aims to reduce this barrier to entry and make digital foams accessible for the masses.
“The performance of the foam is defined by three parameters,” explained Krauss. “I distribute it as 40 percent is the material, 40 percent is the design of the lattice structure and the remaining 20 percent is in how you run it on the machine and post-process it.”
“If we have something looking more like a lattice or something more like springs or something like hexagons, they all have different properties. That’s what makes it difficult for other users to apply it. And that’s why we can help—with all the experience and the data that we have created around Digital Foam, we can help users to accelerate their use of 3D printed foam. We are even at the age of simulating the behavior of foams,” Krauss added.
Looking Forward: Digital Foam in the Manufacturing Mainstream
Additive manufacturing has the potential to create new capabilities and enable innovation for manufacturers and designers.
“For the end-user, people are going to get better products. You’re going to get more comfortable shoes, safer helmets, better office furniture,” explained Walker. “So, I think it’s going to touch people in a lot of different ways, in ways that you can see. In the past, additive manufacturing has improved invisible parts, such as airplane parts. People may not appreciate that additive is helping make lighter, faster airplanes, but you’re going to realize that your 3D printed office chair is more comfortable and different than your old office chair.”