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Designers Benefit in Move From Metal to Other Materials. How Best to Proceed?

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It's time to shift the paradigm in metal prototyping beyond injection molding.

Converting parts from metal to other materials creates weight savings that offers one of the most significant opportunities for heavy industries like aerospace, defense, and heavy transportation. These weight savings are vital to ensuring dramatic cuts in carbon emissions. And while some sectors address the issues of carbon neutrality with more efficient manufacturing and clean energy, most emissions are generated through operation, which is addressed by cutting weight. In addition to increasing performance, cutting weight allows the cost of conversion to quickly be recuperated, whether through reduced fuel usage, increased payloads, or extended range.

The tradition of making parts out of metal is evolving as advanced materials like high-performance thermoplastics present an opportunity to modernize the heavy industry. New material technology allows for parts and components that are equally strong and, in many ways, better than traditional metals, improving performance and efficiency – from decreasing emissions to simplifying maintenance and repair. Instead of just offsetting carbon credits, converting from metal addresses the issue and does so affordably while other more environmentally friendly options like SAF fuels in aerospace remain prohibitively expensive. Further, conversion cuts not only fuel costs but also the need to pay for carbon credits.

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There are alternatives to working with metals.

Shortages and price instability that have recently occurred in supply chains due to global factors like interruptions in shipping and tariffs have also made the prospect of converting from metallic materials more attractive since they are primarily sourced internationally. When price and availability prove unreliable, manufacturers must examine how they can adjust so materials they use are readily available and can be affordably sourced. Domestically produced advanced materials like HX5, a nanocomposite thermoplastic most of our clients convert to, are predictable and advantageous for supply chains and allow for more complex but intense shapes. These more carefully thought out components can be prototyped, manufactured, and mass-produced in weeks versus the months typically needed for machined metal parts.

Engineers Re-imagine Designs

While advanced materials introduce the promise of continuous and reliable availability, they also present an opportunity for engineers to reimagine parts with cutting-edge manufacturing and design. One significant option is in part consolidation. Fewer parts mean fewer parts that can fail, fewer parts in the supply chain, and fewer parts to buy. Part consolidation also takes the costs out of secondary operations – instead of multiple parts in the assembly, machining, and coating, you have one – while also reducing the number of or need for assembly components like hardware or adhesive.

Traditionally, designers wanting to convert from metal have been hesitant to pursue new material options, primarily due to a lack of experience or understanding of how to prototype or design with them. Take one customer we’ve worked with that was looking to lightweight a tank. We were called in to evaluate converting a part that weighed 60 pounds. While the client could reduce the weight of that part to only 30 pounds with HX5, we also helped identify additional smaller parts that could save incremental weight. For example, they skipped over a cable bracket that would save half a pound per part, which was used several times per tank and in several other places across the client’s platforms since it was a common part. Evaluating the parts with an understanding of what could be done created a greater potential for collective weight savings that the client might not have otherwise considered.

With these informed design recommendations directly from an outside engineering team, internal product teams can improve the quality of finished non-metal products and achieve not just more affordable designs but superior prototypes, even when injection molding is involved. While cost-effective for production, injection molds aren’t efficient for prototyping and are only viable after a design is finalized. Frequently, companies, mindful of budget, then settle for prototypes that are not representative of what the finished product will be, which is an especially critical misstep when converting from one material to another, or one manufacturing process to another.

Prototyping

Suppose you plan to migrate to an injection molded part. In that case, it behooves you to have a prototype that is as geometrically equivalent as possible to the anticipated product so what you test in the field will indicate final performance. The iterative step here, and one of the major barriers that have existed, is the expense of an injection mold. An injection-molded prototype is expensive, but prototyping for an injection molded part doesn’t have to be. An accurate prototype can be more affordably extruded or machined with the right analysis, so field testing results in an apples-to-apples representation – allowing you to measure twice and cut once for superior part design.

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The core of an injection molding die.

Many internal product teams are openly hesitant to pursue material conversion and its associated prototyping because they lack the expertise in designing with advanced materials, a gap we work to help them a bridge. An aircraft company we’re working with recently told me, “We just have not had the in-house expertise to do this.” Knowing the gap exists, we educate teams on designing for non-metallics as we help them convert their first few parts, teaching them best practices and how to meet their performance criteria. This allows us to show them the process first and check their work, supervising analysis so that when they are ready, they can follow the same steps in designing future non-metallic parts and components.

Finite element analysis (FEA) has been used for years to improve the design of parts by meticulously analyzing before building, cutting the cost of prototyping. But, more recently, design topology optimization has been used to improve designs further by only putting material where you need it. Design topology optimization is currently used for machined and cast parts at companies working to achieve weight reduction goals where geometries are mostly linear but come with higher manufacturing costs, especially for machined parts.

Analysis

With advanced materials, fiber orientation is an extra and critical consideration to take into account for optimization. Engineering the design of a prototype is different from analyzing it. We extract fiber orientation data during mold flow analysis, then use that as an extra design input in FEA. This process is difficult, takes time and experience. And because they aren’t equipped for fiber orientation analysis, many designers err on the side of caution and use a weaker overall material model, losing that material strength and the entire reason they were using topology optimization in the first place.

This additional analysis in the design process takes raw data, and highly characterized values to more accurately understand how a part made with an advanced material is going to run from mold flow through to FEA. It takes longer to create the complex geometries required for consolidated parts, but this in-depth analysis results in optimized prototype and part design before cutting and tooling.

With the right design topology optimization, the right prototype can be machined instead of molded, allowing you to cut significant time and cost from the prototyping process. Still, ensure the part you send in the field will give you the actual feedback you need. Especially in cases where parts have been consolidated, these prototypes can reflect smarter designs made out of better materials that can do more and weigh less. The key is to have the right design expertise in the process. That understanding does not have to come from an inside product team, especially since conversion from metal is new for so many. Prototyping with advanced materials does not require injection molds, just the right design, and analysis.

It's time to shift the paradigm in prototyping. An injection mold is not essential for prototyping a part that will eventually be injection molded. Rather, proper part design optimization from the start allows for superior and representative prototypes without the expensive outlay of a mold. Machining exact prototypes from billets cuts costs, timelines, and uncertainties first in the prototyping and design process. Ultimately, it counts by introducing the benefits of lighter and better-performing parts made of advanced materials. Delaying the cost of an injection mold until you’ve proven a part in the field creates more assurance that the investment will be worth it. It also means you can put your design to the test and get results sooner without having to wait weeks for the mold itself.

As we reimagine part designs with an eye to environmental impacts, we also overcome the historical barriers to working with advanced materials that can make our footprint a little lighter.

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