Outgassing properties of additively manufactured aluminium

Watson, Steve P.; Breen, Ciaran; Walpole, James; Atkins, Carolyn; Edwards-Mowforth, Maisie; Reynolds, Lucy

doi:10.1117/12.2627331

Cited by 3 publications

(4 citation statements)

References 14 publications

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“…Since outgassing is a consideration for space applications, and it correlates with surface area, 7 the surface area of a 10 × 10 × 10 mm unit cell of each downselected lattice type was determined and plotted in Figure 8b. As outgassing correlates with surface area, it is desired to use lattices with minimal surface area.…”

Section: Lattice Downselectionmentioning

confidence: 99%

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From design to evaluation of an additively manufactured, lightweight, deployable mirror for Earth observation

Westsik,

Wells,

Chahid

et al. 2023

Astronomical Optics: Design, Manufacture, and Test of Space and Ground Systems IV

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Additive manufacturing (AM; 3D Printing) is a process that fabricates objects layer-by-layer, unlocking previously unachievable geometrical freedom in design and manufacture. Its adoption for the manufacture of optical components for nanosats is challenging due to limited understanding of its inherent porosity and outgassing properties; however, AM has plenty of potential for lightweight space-based mirror structures as it enables the use of lattice structures and topology optimisation. AM is particularly relevant to nanosat deployable optics (DO) instrumentation, where a segmented mirror needs to be packed within a limited volume and mass budget. This paper describes the design, analysis, manufacture and metrology of AM mirror petal prototypes for a 6U nanosat DO payload. The objective of the prototypes was to reduce the mass and the part count relative to the conventional design. From the available 33 volumetric lattices including graph, triply periodic minimal surface and stochastic lattices within the AM design software used, two were downselected by using finite element analysis and manufacturability experiments. Prototypes were designed using these lattices, and the geometric and interface requirements of the conventional petal. These were printed, using laser powder bed fusion, in the aluminium alloy AlSi10Mg and post-processed using single point diamond turning. The internal (porosity) and external geometrical properties of the manufactured prototypes were measured using X-ray computed tomography and the optical properties of the reflective surface evaluated using interferometry. By utilising AM, a mass reduction of 44 % and the consolidation of nine parts into one was achieved.

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Section: Lattice Downselectionmentioning

confidence: 99%

“…Overhanging surfaces below 45 degrees relative to the build plate exhibit considerably larger surface roughness 14, 15 which might correlate with higher outgassing rates. 7 Therefore, graph lattices need to be oriented so that individual beams' overhang angle is maximised.…”

Section: Print Orientation Selectionmentioning

confidence: 99%

From design to evaluation of an additively manufactured, lightweight, deployable mirror for Earth observation

Westsik,

Wells,

Chahid

et al. 2023

Astronomical Optics: Design, Manufacture, and Test of Space and Ground Systems IV

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“…To explore the WAAM technology, eight samples were printed in aluminium 5356, four samples had the geometry of a cuboid and four the geometry of a box. The geometries were defined to meet the preferred operational sample requirements of the in-house outgassing rig, 27 which was used to quantify the potential of the WAAM samples to outgas within a vacuum relative to a conventional subtractively machined sample. An internal evaluation of the samples to quantify printing defects was undertaken using X-ray computed tomography (XCT).…”

Section: Waam Evaluationmentioning

confidence: 99%

Understanding the role of additive manufacturing in the development of astronomical hardware

Atkins,

Chahid,

Wells

et al. 2023

Astronomical Optics: Design, Manufacture, and Test of Space and Ground Systems IV

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Lightweight optical manufacture is no longer confined to the conventional subtractive (mill and drill), formative (casting and forging) and fabricative (bonding and fixing) manufacturing methods. Additive manufacturing (AM; 3D printing), creating a part layer-by-layer, provides new opportunities to reduce mass and combine multiple parts into one structure. Frequently, modern astronomical telescopes and instruments, ground- and space-based, are limited in mass and volume, and are complex to assemble, which are limitations that can benefit from AM. However, there are challenges to overcome before AM is considered a conventional method of manufacture, for example, upskilling engineers, increasing the technology readiness level via AM case studies, and understanding the AM build process to deliver the required material properties. This paper describes current progress within a four-year research programme that has the goal to explore these challenges towards creating a strategy for AM adoption within astronomical hardware. Working with early-career engineers, case studies have been undertaken which focus on lightweight AM aluminium mirror manufacture and optical mountings. In parallel, the aluminium AM build parameters have been investigated to understand which combination of parameters results in AM parts with consistent material properties and low defects. Metrology results from two AM case studies will be summarised: the optical characteristics of a lightweighted aluminium mirror intended for in-orbit deployment from a nanosat; and the AM build quality of wire arc additive manufacture for use in an optomechanical housing. Finally, an analysis of how surface roughness from AM mirror samples and build parameters are linked will be discussed.

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“…Outgassing rates were found using the modified throughput method described in Breen, C., et al 2022 . 15 In this method, two nominally identical chambers outgas through two orifices into a pumped central volume. Samples were cleaned, dried, then placed under a vacuum (≈ 10 −6 Pa) within one of the chambers.…”

Section: Outgassingmentioning

confidence: 99%

Lightweighting large optomechanical structures in astronomy instrumentation utilising generative design and additive manufacturing

Wells,

Westsik,

Chahid

et al. 2023

Optomechanical Engineering 2023

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Ground-based astronomical instruments have mass limits to ensure they can operate safely and accurately. Reducing the mass of optomechanical structures relieves mass budget for other components, improving the instrument's performance. Many industries have adopted generative design (GD) and additive manufacturing (AM; 3D printing) to produce lightweight components. This is yet to be implemented in ground-based astronomical instrumentation; this paper aims to provide insight into the advantages and limitations of this approach. The project studied the Extremely Large Telescope (ELT) Mid-infrared Imager and Spectrograph (METIS) threemirror anastigmat (TMA); comparing the conventional, subtractive machined design with GD-AM designs. The TMA was selected due to its bespoke geometry constrained by an optical path, a conventional design which did not consider mass reduction, the size of the part (615 mm × 530 mm × 525 mm) that necessitated a study of different AM methods, and the operational environment (70 K & 10 −6 Pa).The study created mass-optimised designs of the TMA using topology optimisation and field-driven design. The performance of these designs was analysed using finite element analysis and optical ray tracing. It was found that GD-AM designs pass the required optical, structural and modal requirements, with a greater than 30% weight reduction when compared to the conventional design. The study investigated wire arc additive manufacturing (WAAM), a viable method of manufacturing components of the TMA's size. To commence the validation of WAAM for cryogenic environments, samples of WAAM aluminium 5356 were created and studied. The internal and external dimensions of two samples were investigated using X-ray computed tomography and the outgassing rate of two sets of three samples were evaluated to quantify the difference between machined and as-built samples.

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Outgassing properties of additively manufactured aluminium

Cited by 3 publications

References 14 publications

From design to evaluation of an additively manufactured, lightweight, deployable mirror for Earth observation

From design to evaluation of an additively manufactured, lightweight, deployable mirror for Earth observation

Understanding the role of additive manufacturing in the development of astronomical hardware

Lightweighting large optomechanical structures in astronomy instrumentation utilising generative design and additive manufacturing

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