Key elements of a successful thermoplastic gear solution for power transmission (Part 2)

Joseph Elmquist
Segment Technology Manager Gears
Performance benefits, technical feasibility and a competitive price point determine the value of gear applications – a quick dive into these interdepend elements

In Part 1, we considered some performance features of a successful thermoplastic gear solution, including NVH improvements and reduction of weight and inertia. This blog, part 2, focusses on commercial and technical considerations.

Commercially viable

There is no denying, performance benefits must be deliverable at a compelling price point. Key elements within an automotive power transmission gear application include:

  • Delivery of performance includes the manufacturing of the gear component, the delivery of the component to the assembly point, and the assembly of the gear component into the system where the performance benefit is realised. To consistently achieve this in concert with the other critical elements of a successful application, it is important that all elements are considered at the earliest stage of design and integrated throughout the development process.

  • Compelling system value: There are two aspects of compelling value that must be weighed against each other: the value of the performance benefit and the holistic cost of the delivered solution. It should be self-evident that for a successful program the first must be judged more favorably than the second.
    Within the automotive powertrain, the value of a solution’s performance benefit can most commonly be quantified by the alternative means by which the offered level of performance may be reached. For example, the observable NVH of a vehicle is a result of both noise generation and the noise transmission path. While a gear component by reducing NVH generation may offer an NVH benefit as compared to a metal component, it must also offer a benefit as compared to the addition of noise palliatives that reduce NVH transmission and result in a similar perception of overall vehicle NVH. In this manner, the value of the overall solution performance can often be quantified.

Similarly, the cost of a solution must also be evaluated holistically to capture the total cost of the solution as delivered, not just as a manufactured component. While this certainly includes component cost, it must also reflect delivery, assembly, and the addition or subtraction of related system components.  (Un)fortunately, this is a lesson I learned the hard way on one of my first gear programs when an apparently attractive component value was swallowed up by a significant re-tooling requirement that was only discovered late in the development cycle.

Technically feasible

Finally, no matter how attractive the value and performance of the gear solution may seem to be, it must be technically feasible to deliver this reliably and durably. For a thermoplastic gear solution, this is often the most difficult element to realise, and requires the highest degree of technical competence throughout the entire development process.

  • Durable: Unlike performance metrics, durability is binary and must be absolute. On a material level, even high-strength VICTREX™ PEEK material gear grades such as VICTREX HPG™ 240, which are among the strongest thermoplastics available, are less than 25% as strong as a typical steel at internal combustion engine (ICE) running temperatures. However, a thermoplastic gear design tailored to leverage the increased manufacturing flexibility of injection moulding, the distinctive mechanical properties of thermoplastics and the specific operating environment, can often provide the required durability with significant factors of safety.
  • Reliable: Reliability requires the durability and performance of the gear solution to be delivered across the entire system operating range, in all assemblies, over the entire life of the product. For thermoplastic gears, this necessarily entails careful consideration to minimise the effects of manufacturing variability within the product design, the extreme operating conditions of the system including predictable overload situations, and aging simulation correlated to years of test data.

In our recent webinar with "just-auto" we touched on those aspects in more detail including NVH and durability testing data.

Path to future gear innovations

Start with questioning the status quo: To meet complex design challenges, gear innovation starts straight from the beginning. Identifying and addressing the needs from every angle can help to gain the desirable competitive advantage. This is especially critical when developing high-performance thermoplastic gears for power transmission applications. Are you ready unlock the full potential of thermoplastics to adopt innovative turn-key solutions? Then get started today and drop me an email.

About the author

Joseph Elmquist joined Kleiss Gears in 2013 as a lead design engineer and technical lead for new product development of thermoplastic and thermoplastic composite gears. Following Victrex’ acquisition of Kleiss in 2015, he continued to lead the technical development efforts on thermoplastic powertrain gear applications culminating in the successful launch of the first VICTREX PEEK gears for power transmission within the automotive powertrain in 2017. Joseph holds a BS in Engineering Mechanics and a MS in Mechanical Engineering with a focus on nonlinear dynamic mechanical systems from the University of Wisconsin-Madison.

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