Episode 55: Dave Noblin, Greene Tweed

Thermoplastic composites can be tailored to meet specific application needs representing a wide range of properties, such as wear resistance, low friction and dimensional stability — these attributes make them a good alternative to metal components for rotating equipment applications such as centrifugal pumps and compressors.
Source (All Images) | Greene Tweed

In this installment of CW Talks, we explore the use of thermoplastic composites for rotating equipment in variety of sectors from industrial applications to aerospace. We recently spoke with Dave Noblin, product manager for wear-resistant components for Greene Tweed, to learn about how TPCs are being used in this space.

CompositesWorld (CW): Give us a bit of background about Greene Tweed.

Dave Noblin, product manager, Greene Tweed

Dave Noblin (DN): Greene Tweed is a global manufacturer of high-performance thermoplastic composites, electrical connectors and seals. For 160 years, the company has served clients in semiconductor, oil and gas, petrochemical processing, aerospace and a wide variety of other industries where failure is not an option.

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CW: Tell us about the use of thermoplastic composites in rotating equipment across sectors like energy, industrial and aerospace.

DN: We’re seeing a growing demand for materials that can handle extreme conditions. Thermoplastic composites are engineered to withstand very aggressive environments, making them ideal for demanding applications in these sectors, their ability to maintain performance under these conditions enables reliability and longevity.

When considering the life cycle of the equipment, thermoplastic composites can be tailored to meet specific application needs representing a wide range of properties, such as wear resistance, low friction, dimensional stability. This type of versatility allows the engineers to optimize both material selection combined with design for improved performance and durability.

For aerospace specifically, we offer complex composite shapes to replace heavier metal components without sacrificing performance. Our solutions are generally between 40-60% lighter, providing a superior strength-to-weight ratio while still meeting fire, toxicity and smoke requirements.

For the energy and industrial solutions, which is more my area, those components are used in rotating equipment such as centrifugal pumps and compressors. Within those applications, composites enable improved life cycle costs to enhance reliability and efficiency.

CW: How do thermoplastic composites compare to traditional materials such as metals regarding wear, performance and temperature capability?

DN: Most traditional materials in this equipment, like the metals, come with inherent challenges. For example, metals are prone to galling and seizing when there’s high-speed contact, so they’re typically designed with these generous running clearances to avoid that. The downside is that these larger clearances can reduce the efficiency and even lead to reliability issues, especially during upset conditions.

Metals are also more vulnerable to some of the corrosion and wear problems you see in these harsh environments, which can shorten their lifespan. Thermoplastic composites are specifically formulated to address these issues. They don’t gall or seize, which means you can design for much tighter running clearances. This serves to improve the efficiency by reducing recirculation and stabilizing the system, as we discussed before, plus excellent dimensional stability so they can perform consistently over a wide range of temperatures, from cryogenic conditions all the way up to 500º and above. This makes them a very reliable option, even in extreme operating conditions where metals might struggle.

CW: How do the upfront and long-term costs of thermoplastic composites compare to other materials, especially when you factor in maintenance savings or reduced downtime?

 DN: Cost does come up early and often. Thermoplastic composites will have a higher initial cost when you’re considering new build equipment or repairs and maintenance relative to the cost of metals. However, extending the maintenance cycle with improved reliability and/or reducing the energy costs with improved efficiency will significantly reduce the overall life cycle cost of the equipment, as we discussed before.

CW: What are some other hurdles or common misconceptions about thermoplastic composites that you’ve encountered?

DN: We’ve been applying composites and rotating equipment as a company for over 30 years now and in that time, we’ve had really two common misconceptions around these composites that we’ve had to address. It’s a little bit less common now, but early on, there was always a misconception that a thermoplastic composite could not withstand the harsh operating conditions of rotating equipment. So, we’ve invested a significant amount of lab testing to provide the proof of concept, and subsequently partnered with OEMs and end users alike to validate that performance in the field.

As a result, we’ve seen the demand for these materials steadily increase over the years. Secondly, there’s always the concern of cost. The initial cost of outfitting your equipment with composites can be quite a bit higher using a more traditional metal solution. So, in our collaboration with the manufacturers and end users alike, we’ve been able to document many successful field performances through case studies. For example, Greene Tweed composites have been shown to improve mean time between repairs (MTBR) and reduce equipment life cycle cost in rotating equipment, while the initial cost can and may be higher, the long-term savings and maintenance and energy often far outweigh the upfront initial investment. Educating the stakeholders with the real-world case studies can really help shift this perception.

CW: What advice do you have for engineers who are looking at incorporating thermoplastic composites into their rotating equipment designs? Are there key tests or considerations that they need to think about as they’re going about that work?

DN: I’ve been fortunate enough to be in the industry long enough to witness an evolution or a change in the thinking of the younger engineers that come aboard, and I think this is a good thing. They’re certainly more open to applying advanced technology than we seem to have been 25-30 years ago, but one thing that has lingered is a tendency to replace like for like, and install composite components using the same design parameters as used for metals. So, my advice would be for equipment designers to partner with composite engineers and designers to ensure that you’ve got both the optimal material selection and the optimal design. That is going to be the best way to reap the benefits of these materials.