In our latest Technology Tuesdays podcast, Design World’s Michelle Froese speaks with David Church, president of Sorbothane, about the evolving use of viscoelastic materials in shock and vibration design. Sorbothane has been developing components that isolate vibration, absorb impact, and dampen unwanted noise for more than 40 years.
In this discussion, we explore how Sorbothane performs in real-world conditions, including temperature and humidity extremes, high-frequency applications, and complex geometries. We also talk about recent customer requests, such as a non-tacky version of the material, new molding capabilities that allow for more intricate part designs, and ongoing efforts to develop FEA support for digital simulation.
The audio and a lightly edited transcript of this conversation follow below. You can also listen to the podcast with David Church from last year here.
Design World (DW): Hello, Everyone! Welcome to Design World’s Technology Tuesdays podcast. I’m Michelle Froese, and I appreciate you tuning in. Today I’m joined by David Church, president of Sorbothane, for a conversation about the latest in shock and vibration isolation technologies.
Sorbothane has spent over four decades engineering materials and components that reduce vibration, absorb impact, and dampen unwanted noise across a range of industries. This includes aerospace, medical devices, electronics, transportation, and even fitness equipment.
The company’s signature material, also called Sorbothane, is a viscoelastic polyurethane that behaves like a liquid under load. This unique property makes it especially useful in design applications where managing shock, vibration, or acoustic disturbances is essential.
If it sounds familiar, you might know Sorbothane from its original use in popular insoles for shoes. Since then, its applications have only grown. The proprietary material continues to offer smart solutions to some surprisingly complex challenges, and that’s exactly what we’ll be exploring with David today.
David, welcome back. We’ve chatted a few times before, and it’s great to connect with you again.
David Church (DC): Hello, Michelle. Thank you for having us back! We always enjoy our conversations about our company and our material, Sorbothane.
DW: Agreed! First question for you, David: from an engineering design perspective, what makes Sorbothane uniquely suited as a problem-solving material, especially when compared to more conventional solutions like foams, gels, or rubber isolators?
DC: What makes Sorbothane unique is that it’s a viscoelastic material. This means that it behaves like a fluid but also retains elasticity to return to its original shape. Over time, it continues to dampen shock and vibration. Unlike cellular foams, which can break down, Sorbothane is a dense material and holds up much longer.
Gels tend to be stiffer and less capable of absorbing shock and vibration. And with rubber isolators — except for natural rubber, which performs well — most can only dampen in one axis, either X or Y. Sorbothane, because it’s viscoelastic, can perform across multiple axes, which sets it apart.
DW: You’ve mentioned creep resistance before. Can you please walk us through how creep testing is done on Sorbothane, or what engineers should watch for during long-term durability analysis?
DC: Creep testing is pretty straightforward. We use a standard test slug, which is usually one inch in diameter by half an inch thick. Then, we place a weight on it, and measure how much it deflects over time. This could range from hours to months, but we typically test for about two hours.
If the material continues to deform after that period, it’s said to creep and is generally unsuitable as a damping material. Our tests show Sorbothane stops deforming after those two hours, which is one reason it performs so well in shock and vibration applications.
DW: What about environmental conditions like temperature, humidity, or UV exposure? How might those affect Sorbothane’s performance over time, especially for outdoor or aerospace use?
DC: The environment is always critical. The energy put into Sorbothane during use creates its own internal temperature, so our material has a continuous use range up to about 160° F. That’s lower than some synthetic rubbers, which can go over 200° F, but it’s a trade-off given the performance.
Also, Sorbothane is a polyurethane, which tends to absorb water and swell. That’s why we developed a water-resistant variant about 10 years ago, specifically for high-humidity or washdown environments. It holds up well in submerged applications, too.
UV exposure has not been an issue for us. Sorbothane is very resistant to UV, and we’ve used it successfully in aerospace. However, it does off-gas slightly, so in certain critical applications, designers need to be aware of that.
DW: Thanks, David! Let’s talk about high-frequency vibration. How should designers approach geometry or hardness when trying to tune for specific vibration conditions?
DC: High-frequency vibrations are easier to dampen. The key is the shape factor. If you can calculate the ideal shape factor for your specific load and frequency, you can achieve up to 95% isolation.
Low-frequency vibration is much harder to deal with. The best way we’ve found to handle low frequencies is to add weight. Many companies struggle to isolate low-frequency vibrations and sometimes turn to tuned dampers instead.
As for durometer, it really depends. Some applications work best with a 70-durometer, while others work best with a 30-durometer. That’s why we work directly with customers to find the right combination of shape and hardness.
DW: What’s important to know about prototyping with Sorbothane, especially when working with different durometers or wall thicknesses? And does it work with other materials if needed?
DC: Wall thickness is a big factor. In an open-cast mold, we’re limited to about a tenth of an inch thick. If you move to a closed mold, where two halves are clamped together, you can get down to one to one-and-a-half millimeters.
Prototyping depends on the part. If it’s a simple gasket about a tenth of an inch thick, we can die-cut it from sheet stock. Other times, customers send us 3D-printed or metal molds for more complex parts. We can cast directly into those.
DW: What about bonding to other materials? Is that something you’re often asked about?
DC: Yes, quite a bit. Sorbothane is naturally tacky. We can cast it directly to certain materials like fabrics and metals. For metals, we typically apply a primer first to promote adhesion. The same goes for thermoplastics. As long as we apply the right bonding agent, Sorbothane adheres very well.
DW: I know Sorbothane offers several online calculators for load rating, impact, and vibration. Can you walk us through how engineers can make the most of them?
DC: Those tools are used by about 500 people a month, and we use them internally too. The load calculator helps determine your shape factor. You can choose a disc, washer, square, or rectangle and test different dimensions and durometers.
Once you’ve got your shape, the vibration calculator shows how it will perform at your frequency, whether it’s 10, 60, or 70 Hz. You can adjust thickness or hardness and see how those changes affect isolation.
Lastly, the shock calculator allows you to enter the drop height, distance, or velocity. It estimates deflection and helps ensure you’re staying within a safe range… typically less than 30 to 35% compression for shock absorption.
DW: Are there any other modeling tools you’re working on, or have you seen an increase in digital simulation?
DC: We’ve seen a bit of digital modeling, but not much FEA use yet. We’re working with a local university to develop a full FEA model for Sorbothane. It’s something we know would be helpful for our customers, so that’s in progress.
DW: That’s great! Have there been any unique geometries or case studies where Sorbothane performed better than expected?
DC: How can I ever be surprised that Sorbothane worked better? We know it’s one of the best materials for isolating shock and vibration.
But over the years, we’ve developed new molding techniques. Sorbothane is a liquid-cast system, not injection molded. But, we’ve added runner and venting systems that now let us produce more complex parts. Some of them look almost like they were injection molded.
DW: You must have read my mind. I was going to ask about future capabilities. Anything else you’re working on for the next few years?
DC: We’re always trying to improve Sorbothane. Right now, it’s naturally tacky. That can be helpful in some cases but a problem in others where people want to reposition parts. We can coat it to make it non-tacky, but that adds cost. So, we’re developing a version that comes out of the mold non-tacky but performs the same. That’s a big focus for us right now.
DW: Appreciate the insight, David! I have just a couple more questions. What should engineers or entrepreneurs keep in mind early in the design process when evaluating Sorbothane?
DC: Wall thickness is key. If you’re designing a part with very thin walls, reach out to us first. Sharp corners are also a challenge because they trap air and can cause voids. We always recommend incorporating radii into designs, so the material flows better in the mold. Radii are good. Sharp corners are bad. Thin walls are also more difficult, though not impossible.
DW: Great information! Last question… is there anything I didn’t ask that you’d like to add before we close?
DC: I think we covered a lot of great topics. I’ll just say that Sorbothane is one of a kind. It’s not the answer for everything, but 95% of the time when people come to us, it’s because other materials failed. And 95% of the time, we’re able to help. We encourage people to come to us first. It’ll save time.
DW: Interesting, for sure! Sorbothane.com is the website, correct?
DC: Yes, sorbothane.com.
DW: Thank you so much, David! It’s been great connecting with you again.
DC: Thank you, Michelle. Always great to talk with you!
DW: And thank you to our listeners for joining us today. To learn more, visit Design World at designworldonline.com, and be sure to subscribe and share this podcast wherever you listen. Thanks again and have a wonderful day!
Design World
Filed Under: PODCASTS