How to: Materials Selection in Sustainable Product Design

Industrial designers and product manufacturers can no longer afford to sidestep the question of sustainable product design. But how do you rank and select the best sustainable materials, processes, and production methods while taking into account cost, time, and existing tooling and infrastructure? 

In the realm of sustainable engineered plastics, the options and considerations are endless, but we’ve put together some rules of thumb to keep in mind as you navigate the materials selection process. This is where material science, engineering, sustainability, and human-centered design intersect.

Let’s start with a simple truth that may not be said often enough:

It is okay to use plastic for durable applications

Plastics have become ubiquitous in our daily lives, and for good reason. They are versatile, robust, cost-effective, recyclable, high-quality, and long-lasting. Today’s library of options is immense and the industry has advanced the technical capabilities of engineered resins to offer new levels of performance. Whether off-the-shelf or custom-tailored to specific needs, plastics offer irreplaceable materials solutions for a huge variety of applications.  Single use plastics are the main problem, with 51% of all plastic production going to packaging. This is a critical and urgent concern for all of us to address. However, durable uses, if well engineered, reduce CO₂ and keep products safer, and if designed well, can be part of the circular economy.

The key to using plastics in sustainable product development is to combine carefully selected materials with the design expertise on how to apply them. Traditionally, materials selection is the output of a product’s functional requirements and user needs. However, sustainability considerations drive the conversation the other way: our users and our planet are requiring sustainable materials which then play a major role for how a product is designed from the outset. The two disciplines, product design and sustainable materials science, are more interwoven than ever before.

Navigating the co-dependent nature of these two disciplines in the creation of sustainable products can be tricky. Hopefully the following tips will be helpful, but if you’re wondering where to start, or are working on a project where the sustainability story is too critical to get wrong, we’d love to talk!

Sundberg-Ferar and Material ConneXion have the knowledge and skills you need to select the right materials and design the right product for your sustainability story.

So, now that we have the green light to use plastics for the right applications, let’s layout some high-level guideposts for how to select the best sustainable materials and discuss what a well-engineered and well-designed sustainable plastic product might look like.

Go ‘monomaterial’ when you can

Using just one kind of plastic for multiple parts achieves the potential of greater circularity, both in production and at end of life. This simple approach enables optimum recyclability pathways without intermediate steps of disassembly or materials separation. Plastic materials are especially compatible with this strategy. Molded in snap fittings, press fittings, and staking/welding joints all eliminate the use of fasteners entirely. However, these require clever design work and detailed familiarity with manufacturing strategies to be successful.

When monomaterial is not an option, there are other sustainable product design strategies that can be applied to facilitate ease of disassembly. Smart part break-up strategies, strategic fastener strategies and monomaterial definition of sub-assemblies can still be valuable in the end of life sustainability equation.

Pictured: Material ConneXion’s materials library

The Olefins Are Your Friends

Polypropylene and polyethylene in all their forms are ‘cleaner’, meaning they have simpler chemistry without problematic additions of chemicals like chlorine or styrene. They’re more easily recyclable, and there is a greater opportunity for monomaterial production since the two resin types can often be recycled together for certain uses. In addition to these sustainability advantages, this materials group is generally low-cost, readily available, extremely robust, and adaptable to a variety of manufacturing processes. There are special considerations, however. Specifically for polypropylene, dimensional instability has earned this material the affectionate nickname poly’warp’ylene. Don’t let this reputation scare you! There are design strategies that can help: robust joining methods, ribbing strategies, manufacturing process control, and even strategic adjustments to the overall part shape itself can produce accurate parts for most applications.

Recycled content is good, post-consumer is better, chemically recycled is ‘best’

Put in as much as you can, as often as you can, and if you can get your hands on chemically recycled versions, (i.e. resins that have been recycled using solvents and other chemical means rather than mechanical grinding and remelting), make it 100%! These sustainable materials processes and production methods are breaking new ground on product life-cycle options and producing viable materials along the way.

Intentionally supporting innovative recyclability options is an example of product stewardship. This is a systems-thinking approach that pursues a more holistic initiative of owning your product’s end of life. A true circular product life cycle is ultimately the greatest way to make sustainability impact. There are ways to design strategically towards these goals and future-proof your product portfolio in the process. If you’d like to learn more, here’s a great walkthrough of Life Cycle Thinking.

At Least Consider Renewables

Though off to a relatively slow start, renewably sourced engineering resins exist and have viable performance. These plastics use a large proportion of raw materials that have been grown, such as corn, soy & castor beans, algae, and sugarcane, rather than sourced from oil. Polycarbonates, nylons, polyesters, POMs and others have been developed with significant amounts of bio-based sources, with advancements occurring regularly. 

Some of these innovative options may require adaptation of product requirements. This is where it’s important to recognize that good product design needs to be driven by the intended materials. If a sustainable material option is available, and its specifications are close to what the product requires, what other clever design strategies can be applied to bridge the gap? Or, what other strategic pathways can be pursued to re-prioritize product requirements and bring sustainability to the forefront?

Cost too is often perceived as a downside of emerging sustainable materials. This is not necessarily true and needs to be analyzed on a case-by-case basis considering the specific product goals. Regulatory considerations are becoming a part of this story too as new legislation emerges on plastics post-consumer recycled content and disposal. Also, consider that exceptional product design itself can drive new value for consumers. Profitability is more complicated than simply studying competitive price points and strategizing a target position; find ways to differentiate from competitors and invest in quality design.

Use Less Material

A basic approach to sustainable product development is to simply be efficient. The design tools available today offer incredible opportunities for dematerialization. Optimization through traditional engineering, CAE and even relatively new techniques in generative design can produce strong and robust solutions that use only as much material as required. Every ounce of plastic saved will quickly add up over the course of production.

Modularity can also be an efficiency approach that can help reduce the materials, energy and CO2 associated with production tooling and the efforts for manufacturing. Modularity requires undertaking the design of multiple products at one time. This is complex and takes time, effort, and skill. However, these iteration loops are well worth the design energy spent and can have a significant impact on the sustainability of the factory floor itself.

And a final way to use less: think long term. A robust product with a timeless design can be put to good use for decades. Design for this intentionally by applying strict durability requirements and quality aesthetics.

Be honest and influential with design

There are a myriad of material options that target sustainable objectives through their production methods and end of life opportunities. However, many have unique characteristics, colors, textures, and feel. Good industrial product designembraces these traits and helps tell the story of the material technology in ways that emotionally connects to the user. This type of honest design not only promotes a products success in the marketplace, but it also inspires awareness and momentum in the material itself so that it can be expanded to other applications.

There are a myriad of material options that target sustainable objectives through their production methods and end of life opportunities. However, many have unique characteristics, colors, textures, and feel. Good industrial product designembraces these traits and helps tell the story of the material technology in ways that emotionally connects to the user. This type of honest design not only promotes a products success in the marketplace, but it also inspires awareness and momentum in the material itself so that it can be expanded to other applications.

At a deeper level, how a material is applied and the way that a product is designed holds unique opportunity to influence behaviors. This power of design can be harnessed to change perceptions around sustainability. For example, Sundberg-Ferar helped SproutsIO design a growing device that targeted needs of food-lovers and chefs in their design efforts and offered them opportunities to grow heirloom breed vegetables indoors. The replaceable seed cartridges for this product were designed with garden compostable materials to influence a cycle of composting within their user groups. This in turn emotionally connects their users with food production cycles and inspires awareness in sustainable agriculture.

Sustainable product development is a critical undertaking that requires informed knowledge on ideal materials solutions, and the expertise of how to apply them. This can be a complex route and there are no true golden rules; each application needs careful consideration based on the product’s functional intent, user needs, and business case.

Materials advisors, Material ConneXion, and product innovation studio, Sundberg-Ferar, put these guidelines together to help you on your way, but if you’re looking ahead to your next (or first!) sustainable product initiative and you could use some expert guidance and support, we‘d love to chat with you! Contact us to learn how we can help make your sustainable product portfolio a market success.

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