In its early days, additive manufacturing (AM) technology was geared primarily towards design and rapid prototyping applications. Recently, however, additive manufacturing is increasingly being used to produce high-performance mechanical components from technical and refractory materials. This is especially prevalent in space and aerospace engineering, where additive manufacturing’s combination of precision, speed, versatility, and affordability make it an irresistible option. It is also an attractive tool for its ability to print refractories in lightweight architectures, providing high temperature performance at a fraction of the weight of conventionally-fabricated refractory metal parts. In this article, we look at the key advantages of AM versus traditional subtractive manufacturing, and how these are being used to change the landscape of space engineering.
In 2013, NASA carried out tests on a new rocket injector design. During these tests, the subscale injectors were subjected to extreme pressures and temperatures exceeding 3,300 C, for over 46 seconds, while burning liquid oxygen and hydrogen gas. The tests were a success – one engineer overseeing the tests noted that the new components ‘operated beautifully’, withstanding the extreme conditions without any sign of failure. Even more impressively, these high-performance parts were each made in a single-step additive manufacturing process.1
The subscale injectors previously used by NASA for these tests were manufactured using traditional “subtractive” methods: milling and machining bulk material and joining parts together. The injectors had four parts and took over six months and $10,000 apiece to produce. Manufacturing the new injectors additively not only produced functionally indistinguishable components but did so in just under three weeks – and at half the cost.
NASA’s fuel injectors are just one example of several ways in which additive manufacturing technologies are being harnessed for space applications to improve the efficiency of manufacturing and performance of components.
The Advantages of Additive Manufacturing
The benefits of additive manufacturing in space engineering are numerous. Firstly, additive manufacturing enables the construction of geometrically complex components that would otherwise require highly specialized production methods. Components like NASA’s rocket injectors, which would have once required many distinct processing steps, can now be produced in one continuous AM process. Researchers at the German Aerospace Center recently designed and prototyped a reusable rocket engine, produced via AM. The new additively manufactured design reduced the number of parts from 30 to 1, reduced weight by 10%, and offered improved performance over the old design.2
Additive manufacturing also offers significant economic advantages compared to traditional subtractive manufacturing techniques. Components can effectively be produced on-demand using a single machine, virtually eliminating the need for re-tooling or revision of manufacturing procedures for new parts, meaning economy of scale is far more easily achieved. AM can provide economy of scale for small unit volumes – often as low as one – meaning manufacturers can order or produce components as and when they are required rather than having to order thousands of components to achieve economic efficiency.3 Additive manufacturing is at once an economically viable way of producing aerospace components in large quantities and producing highly customized components.
Finally, the crucial advantage of additive manufacturing for space applications is that it can be used to drastically reduce the mass of components. Whereas subtractive manufacturing almost always results in ‘solid’ components of uniform density, additive manufacturing techniques can be used to easily hollow-out components with pockets, holes and closed cells to significantly reduce the mass of components. For example, weight reductions of a staggering 70% have been demonstrated for satellite components produced using AM.4 This is not to be sniffed at: reducing the mass of satellite components drastically reduces the amount of fuel required to launch the satellite and to maneuver it once it reaches orbit. For space applications, the importance of shedding every possible gram can hardly be overstated, and AM provides a way to reduce the mass of existing components without compromising performance. This is particularly crucial when it comes to generating high-performance components from dense refractories and technical metals.
Additive Manufacturing Solutions for Space Engineering
The applications for AM in space engineering are virtually unlimited, chiefly because there are very few components used in space technologies which would not benefit from reduced mass and improved turnaround times. AM is a prime candidate for the manufacture of satellite propulsion systems and shielding, rocket, and space vehicle components (such as those used to clean up space debris).
H.C. Starck Solutions is applying its years of experience as a global leader in refractory metal solutions to redefine what is possible with AM technology and the use of refractory metals in the space sector, and striving to stay ahead of the curve in the rapidly changing AM market. 5 It is taking full advantage of the light weighing capabilities provided by AM to offer refractory metal solutions where they were not being considered in the past.
Following significant investment in the development of AM expertise and methodologies on a variety of AM platforms, H.C. Starck Solutions has become a world-leader in the use of AM techniques with a broad range of refractory metals for high-performance applications in space engineering. H.C Starck Solutions now has know-how in producing precisely engineered three-dimensional components from challenging materials such as tungsten, molybdenum, niobium, tantalum, and their alloys; with additional metals available on request.
H.C. Starck Solutions also provides engineered AM feedstocks for printed part applications in space engineering: high-density spheroidized refractory metal powders with finely-tuned particle size distributions, as well as wires specifically designed for a variety of AM deposition techniques.