Reducing the electrical conductivity of vibration isolators with elastomer solutions

Sponsored by Hutchinson

When it comes to the electric vehicle market, it’s not just consumer cars that are getting all the attention. While electrified automobiles such as sedans, pick-up trucks and SUVs are becoming increasingly popular choices among buyers, EVs for commercial purposes are also seeing a large increase in demand. 

In fact, more than 100 companies in 80 markets, including big names such as DHL, Amazon, FedEx and UPS, collectively increased the number of commercial electric vehicles in their fleets by 23 percent in 2020, according to the International Energy Agency.

Just like gas-powered vehicles, solving shock and vibration challenges is an important factor in the design and manufacturing of EVs. Successfully mitigating unwanted vibration, noise and mechanical shock during operation of these vehicles helps provide a smoother and safer ride for both operators and passengers. Addressing these potential issues can also help protect the equipment and lengthen its life, leading to lower overhead costs in the long run. 

For more than 160 years, our company has been a world leader in engineered rubber products and shock and vibration solutions. Our designs are so effective and renowned that they have been copied by shock and vibration isolator manufacturers around the world. What really separates us from the competition is our customer-oriented philosophy and experience in designing and manufacturing custom parts for our clients. 

Our extensive noise, vibration and harshness (NVH) expertise was put to the test when we were approached by one of our clients—an innovative electrified powertrain solution provider for commercial transportation—about their urgent need for a vibration isolation mount with custom specifications and low electrical conductivity. This solution needed to electrically isolate a battery pack from surrounding components in a vehicle to improve system performance, reliability and operator safety. Within only two weeks, our team was able to create a brand new elastomeric compound and prototype that exceeded their expectations and requirements.

The Problem

Since we had already worked with this client on incorporating vibration isolators into their battery mounting design, they were familiar with our reputation as a global leader in vibration control technologies. Although they were satisfied with many of the choices available in our initial catalog product offerings, the client was looking for an additional vibration isolation mount with unique specifications and lower electrical conductivity than those made from traditional rubber.

As a solutions provider with extensive materials expertise and in-house testing capabilities, we were well-equipped to work on developing a mount that met the client’s needs. First, we considered an alternative way to achieve electrical isolation at the mounting locations by introducing non-conductive insulating components between the vibration mounts and the battery module. Due to space restraints within the design as well as assembly complexity, we concluded that we needed to develop a new elastomeric compound in order to provide the necessary electrical resistance. 

Elastomers are well suited for use in shock and vibration isolators, as they have a high energy storage capacity and can easily mold into any shape. This design flexibility allows for tailoring of multi-directional stiffness characteristics and nonlinearity (travel limiting and snubbing) required for ground vehicle vibration and shock isolation. 

Time was also a factor in this situation, as the new part needed to be delivered to the client within two weeks. This was to ensure that the client stayed on schedule so they could build demonstrator trucks for customer exposure and feedback at an upcoming tradeshow.

Added Challenges and Solution

When creating a new elastomeric compound, it’s important to fully understand the trade-offs of an elastomer’s mechanical properties, durability, cost and more. Neither the client nor our engineering team wanted to solve this issue of conductivity by creating a solution with a shorter service life, a higher price point or any other compromise. In order to best address this challenge, our engineers worked alongside our client’s engineering team to define the specific requirements needed for the desired outcome. 

In the end, we created a solution focused on electrical conductivity with mechanical properties and environmental capabilities that would meet the expectations of the vehicle/transportation market. 

We formulated two different elastomer compounds that incorporated our proprietary carbon nanotube technology to tailor the elastomer’s conductivity level and other properties important to the client. Two different sets of the low conductivity prototype isolators were molded, in unique shades of green, to identify them as high resistivity rubber mounts. They were then installed on a development vehicle and underwent a series of tests in the client’s engineering lab to determine their performance. Ultimately, the electrical resistance exceeded the client’s requirements by a large margin. The entire process was finished within two weeks—perfect timing as the client needed these parts quickly. Upon completion of this project, the client was extremely satisfied with the results.

Custom Design and Manufacturing

As a service company first and foremost, we view our client’s problems as our responsibility. Having this outlook helps us deliver extraordinary services to our customers every single time. 

This case study is an excellent example of how we use our vast resources and capabilities to produce a positive custom result. By leveraging our full analytical and CAD capabilities (including non-linear 3D FEA) as well as our proprietary analytical tools, we can gain a complete understanding of a client’s problems. Computer-aided engineering and design technology helps us perform static and dynamic analyses that are required in order to support each isolation solution. We work closely with our customers to make sure we deliver parts that are optimized for performance, weight, complexity, cost and packaging. 

We own an extensive historical materials database, have tool design capabilities, and as showcased by this successful project; we can compound new elastomeric materials. 

With more than a century and a half of experience working in rubber and elastomeric materials technology, we have worked tirelessly to innovate and improve performance of this technology. Some advancements we have made in this field include improvements on fire and smoke toxicity, heat resistance, longevity and fatigue life, damping and—in this example—lower electrical conductivity. Our team has experience working with materials such as natural rubber, neoprene, EPDM, Butyl, Nitrile, HNBR, Silicone, Fluorosilicone and Fluoroelastomer. 

Process development is a key aspect of our operations, as it helps us ensure quality and highly-repeatable product results. Extensive in-house testing capabilities, and contacts at outside test facilities help us achieve these successful outcomes. Our experience working to provide noise, vibration, shock and motion control solutions in industries such as energy, medical, defense, aerospace, construction, food, computers, robotics and more has broadened our capabilities and overall knowledge.

Whether a problem can be solved by one of our thousands of off-the-shelf designs, by adjusting an existing design or through a completely new part, we are well-equipped to provide world-class and precisely engineered shock, vibration and motion control solutions for all industries, including in electric vehicles. 

If you are interested in learning more about our noise, vibration and shock solutions for the electric vehicle industry, please reach out to us online or by calling (508) 417-7000. 

Sponsored by Hutchinson