Monomaterialism
What is monomaterialism, and why should you care about it?
Monomaterialism describes a part or assembly made from a single material. Pretty simple, right?
Across industries, there are valid reasons for building with a variety of materials. Snacks are packaged in multi-layer pouches with individual materials contributing their strengths: protecting the goods inside, sealing out humidity, blocking UV light, and conveying the brand. Automotive interiors prioritize plush materials in areas with human contact and robust, heat-resistant materials in areas that see direct sunlight. A toothbrush might have a polypropylene handle to resist bending paired with overmolded TPE to provide a soft grip.
So why might you strive for monomaterialism in your design?
💵 Cost. For injection molding, if all components are made from the same polymer, the upfront mold design and per-part costs can be significantly reduced. In some cases, multiple different parts can be made using one mold. For 3D printing, monomaterialism simplifies filament and resin allocation and can lead to faster and more efficient parts batching. Across the board, monomaterialism reduces supply chain and production strains.
🧩 Compatibility. Not all materials play well together. If your design uses dissimilar metals in contact with one another, it could be susceptible to galvanic corrosion and premature failure. If your product sees significant temperature fluctuations, varied degrees of thermal expansion can cause warping and cracks. These challenges have engineering solutions, but they can come with significant development time and costs.
♻️ Sustainability. When a product inevitably reaches the end of its life, its mass represents trapped emissions that can do no useful work. In order to do useful work again, materials must be identified and extracted in an efficient and economical way. This is arguably the largest hurdle to modern recycling programs. Separating multi-layer snack bags for recycling is immensely difficult and expensive. Monomaterialism facilitates the sorting of parts and entire assemblies by their material, enabling industrial processes and curbside collections alike. It significantly increases a product’s recycling or remanufacturing potential, even if the processes themselves haven’t matured yet.