Aerospace Manufacturing - June 2022
Current delays, shortages, and price instabilities in supply chains have made the prospect of converting from metallic materials in the aircraft interiors industry more attractive than ever. Alpine Advanced Materials makes its case for nanocomposites.
First triggered by the pandemic and further exacerbated by the war in Ukraine, uncertain supply chains and cost increases in aluminium, titanium, and magnesium are forcing a closer look at thermoplastics. When price and availability prove unreliable, manufacturers must pivot so the materials they use are readily, predictably, and affordably available.
One benefit of this is that converting parts from metal to a lighter weight material offers one of the greatest opportunities for heavy industries, such as aviation to make dramatic steps in sustainability. While some industries address the issues of carbon neutrality with more efficient manufacturing and clean energy, most emissions in the airline industry are actually generated through operation, which is addressed by cutting weight of the aircraft. In addition to increasing performance, weight reduction can help recuperate the cost of conversion, whether through reduced fuel usage, carbon credit savings, increased payloads, or extended range. Instead of just offsetting carbon credits, converting from metal addresses the issue, and does so affordably while other more environmentally friendly options like sustainable aviation fuels remain prohibitively expensive.
In one conversion case, a manufacturer used HX5, an engineered nanocomposite from Alpine Advanced Materials, to make parts that were 40-50% lighter than when made with milled aluminium, resulting in significant weight savings across the aircraft. In another case, a global aerospace equipment manufacturer in partnership with a major airline evaluated the replacement of 34 machined aluminium parts on a Boeing 777-300ER, and found the result was a weight savings of almost 1,000kg, which would achieve up to 6% fuel savings. In addition to cutting fuel costs, converting from metallic to non-metallic materials reduces the need to pay for carbon credits.
Additionally, components made with advanced materials are greener to manufacture – injection moulding with HX5 results in 44 times less CO2 emissions than milling an aluminium part. Plus, manufacturing with traditional materials typically requires machining a design out of a large block of metal, resulting in as much as 70% material waste, whereas injection-moulding with HX5 requires only the exact amount of material needed to produce the design, resulting in 0% waste. The raw materials used (and more reliably sourced) can even be recycled by being reground and used for non-production parts such as samples and prototypes, or for purge and setup for new HX5 components.
The default to make parts out of metal is also evolving as the development of advanced materials like high-performance nanocomposites presents an opportunity to modernise 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 operational efficiency – from decreasing emissions to simplifying maintenance and repair. Domestically produced advanced materials like HX5 are not only predictable and advantageous for supply chains but are also capable of maintaining strength in more complex 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.
Traditionally, aircraft interiors designers wanting to convert from metal have been hesitant to pursue new material options, mostly due to a lack of experience or understanding on how to prototype or design with them. For example, with advanced materials, fibre orientation is an extra and critical consideration to take into account for optimisation. Engineering the design of a part is different from analysing it, a process that is difficult and requires time and experience. Too many designers skip this step and end up using a weaker overall material model.
This additional analysis in the design process takes raw data and highly characterised values to more accurately understand how a part made with an advanced material is going to function. Although it takes longer to create the complex geometries required for consolidated parts, this in-depth analysis results in optimised prototype and part design prior to cutting and tooling.
If a manufacturer’s plan is to migrate to an injection moulded part, then it makes sense to have a prototype that is as geometrically equivalent as possible to the anticipated final product so that field tests are actually indicative of final performance. However, if the manufacturer opts to machine a prototype, which admittedly cuts significant time and cost from the process, they risk compromising the mechanical properties the advanced material offers when injection moulded.
The iterative step here, and one of the major barriers that has existed, is the expense of an injection mould. While cost-effective for production, injection moulds are not the most efficient option for prototyping and tend to only be viable after a design is finalised. Oftentimes, companies, cognisant of budget, then settle for prototypes that are not actually 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. With the right analysis, an accurate prototype can be more affordably produced so designers can measure twice and cut once for superior part design.
The beauty of advanced manufacturing is engineers can use it to explore new ways to get the job done. One prototyping option Alpine has used with clients is to use preform injection moulding with Addifab, which can deliver complex injection moulded parts without a large tooling investment. This method 3D prints a tool cavity injection mould, a negative of the designed part, then moulds the prototype using the dramatically cheaper 3D printed mould. Once produced, the 3D printed mould is dissolved away, leaving a prototype that takes advantage of the injection moulding and flow to give both proper design and strength requirements. This allows clients to avoid investing in a tool as much as $60,000 until they feel confident that the design will perform exactly as needed.
Another option Alpine has tested with clients is to 3D print a metal insert, a simple mould base, that can be injection moulded to produce a more affordable prototype that will deliver the mechanical, aesthetic, and performance characteristics needed for full field testing. Dramatically more affordable than a purpose-built steel tool, it is also ideal for short run parts like those in aerospace manufacturing. Both choices increase design freedom in a dramatically shorter time span since manufacturers can put design to the test and get results sooner without having to wait weeks for the mould itself. Delaying the cost of an injection mould until the part has been proven assures the ultimate investment will be worth it.
Aerospace manufacturers with primary structures that use 2000-, 6000-, and 7000-series of aluminium and other constituent materials like magnesium, an aerospace material itself, have had problems with availability, lead-times, and cost. Additionally, some advanced thermoplastics have been affected as compounders of Torlon have had difficulty acquiring ingredients or seen steep grade increases, and some ingredients from overseas have been delayed, which can cause even further delays for defence level customers.
By domestically sourcing engineered nanocomposites like HX5, a material option that is 50% lighter and 93% the strength of 6061-T6 aluminium, aerospace manufacturers can not only survive but also thrive through current major global and environmental impacts. Reimagining the process of designing, testing, and producing aerospace parts will reduce drag on an industry constantly working to soar into the future.
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