Additive Manufacturing, industrial 3D printing, has started to revolutionize the way we build products. Especially when combined with Computational Engineering, it now allows engineers and designers to create complex geometries that were previously impossible or expensive to produce. Most 3D-printed objects, however, are still made out of a single material. With the advent of multimaterial printing, Additive Manufacturing is poised to take another leap forward.
In traditional manufacturing, the material used is a constant. If you need diverse properties, you have to assemble the object from multiple parts. In contrast, Additive Manufacturing builds objects particle by particle from scratch, and this process allows for the modulation of material properties through the printing process. Combining different materials in a single print is the logical next step, giving engineers a fourth dimension to play with. They can adjust the composition in addition to its shape, size, and surface area.
Multimaterial Additive Manufacturing opens up a new dimension of functional integration. For example, combining cheap and expensive materials where needed can result in significant cost savings. Engineers can also distribute heat-conductive paths inside a geometry or combine current-conducting and insulating materials in one print. Multimaterial printing can also create surfaces with regional properties, that are challenging to achieve with post-printing treatments.
However, most multimaterial printing methods are still in their infancy. Multimaterial powder bed printing, for instance, takes much longer and can cause problems with the de-mixing of the metal powders afterwards. Many materials require individual post-treatment, and some may not be compatible in terms of melting or sintering temperature, shrinkage, etc.
Computational Engineering is the perfect tool to capture these diverse multimaterial design aspects. Just as shapes can be iteratively tested and optimized in an algorithm, material distributions can be easily varied by changing the logic how materials are split, overlapped, even dithered (for virtual alloys), in different areas within a part.
While multimaterial polymer printing has been around for a while, combining different types of metals in one print job is not an established process yet. The Fraunhofer IGCV Research Lab in Augsburg, Germany, has developed a dual-metal selective laser melting (SLM) technology with very high precision. We have been working with Fraunhofer for the past couple of weeks to build an integrated workflow that combines Computational Engineering with their unique system. As our first example we chose a fluid/fluid heat exchanger that we introduced in a previous post.
The design is based on the concept of producing the inner tubes from copper to maximize heat conductivity and the outer shell from stainless steel to ensure structural integrity and non-reactivity. We also use steel for the volute and piping where no heat exchange is desired.
The Fraunhofer system is based on an SLM Solutions powder-bed metal printer, with a custom developed recoater system. Each layer is recoated two times, once for each material. A suction device with a a magnetic sorting system un-mixes the metal powders for repeated usage. The result is an object that combines both materials in an intricate intertwined geometry.
Multimaterial printing is clearly the future of Additive Manufacturing. While most techniques are not fully developed yet, the potential benefits are significant. Multimaterial printing allows for a previously unheard-of level of functional integration. The resulting designs do not need to be assembled from many parts, but can be manufactured in one go. The result will be cost savings, and the ability to create products that were impossible before.
As these production technologies mature, they will enable many applications, that are a perfect fit for our Computational Engineering approach.
