Towards understanding and eliminating defects in additively manufactured CubeSat mirrors

Snell, Robert M.; Atkins, Carolyn; Schnetler, Hermine; Chahid, Younes; Beardsley, Mat; Harris, Michael; Zhang, Chenxi; Pears, Richard; Thomas, Benjamin; Saunders, Henry; Sloane, Alexander; Maddison, George; Todd, Iain

doi:10.1117/12.2629935

Cited by 4 publications

(8 citation statements)

References 17 publications

(21 reference statements)

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“…Previous research shows that the porosity in the vicinity of substrates is minimised when substrates are printed in a vertical orientation. 10 Minimising the porosity in said locations is critical for acceptable optical surface quality after SPDT.…”

Section: Print Orientation Selectionmentioning

confidence: 99%

“…This printer has been used in an earlier study which focused on optimising print parameters with the goal of minimising porosity in the vicinity of surfaces. 10 These custom settings were used during in the printing of the graph prototypes. Table 5 summarises the machine's specifications.…”

Section: Additive Manufacturingmentioning

confidence: 99%

“…The circularity of the pores suggests that the pores were created through overheating, which has caused pores to form at the bottom of the melt pool, this form of AM porosity is know as keyhole porosity. 10 Porous reflective surfaces are not desirable and a parallel work stream is investigating methods for reduction. The objective of this research was to focus on the design and manufacture, whilst accepting that an external AM bureau would offer a short lead time, but not optimise the print parameters.…”

Section: Micro-roughnessmentioning

confidence: 99%

“…On the other hand, the use of AM introduces unique challenges with design 5 and post-processing, 6 and the outgassing properties of such components. Challenges encountered and overcome in previous work include connectivity of internal volumes for powder removal, 8 self-supporting lattice structures and quilting effects, 5 isolating screw pressure induced by mounting from the optical surface, 9 porosity beneath the mirror substrate 6 affecting the results of Single Point Diamond Turning 10 (SPDT) which increases scattering. Lightweighting of mirrors has been achieved by utilising beambased periodic lattice structures 5 , 11 2-D foam and volumetric Voronoi stochastic lattice structures 12 , 13 and optimising them using topology optimisation.…”

Section: Introductionmentioning

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: Print Orientation Selectionmentioning

confidence: 99%

Section: Additive Manufacturingmentioning

confidence: 99%

Section: Micro-roughnessmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

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

Self Cite

View full text Add to dashboard Cite

show abstract

“…To improve the surface in the future, alternative printer settings can be utilised to minimise the lack of fusion, furthermore, heat treatments, such as hot isostatic pressing (HIP) can be used to close porosity within the AM parts. 29…”

Section: Roughness and Cosmeticmentioning

confidence: 99%

Lightweight, aluminum, mirror design optimization for conventional and additive manufacturing processes

Paenoi

Bourgenot²,

Atkins³

et al. 2022

Advances in Optical and Mechanical Technologies for Telescopes and Instrumentation V

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Lightweight, aluminum, freeform prototype mirrors have been designed and fabricated by a Thai led team, with UK support, for intended applications within the Thai Space Consortium (TSC) satellite series. The project motivation was to explore the different design strategies and fabrication steps enabled by both conventional (mill, drill, and lathe) and additive (3D printing) manufacture of the prototype substrates. Single Point Diamond Turning was used to convert the substrates into mirrors and optical metrology was used to evaluate the different mirror surfaces.The prototype criteria originated from the TSC-1 satellite tertiary mirror, which is designed to minimize the effect of Seidel aberrations before the beam enters the hyperspectral imager. To converge upon the prototype designs, Finite Element Analysis (FEA) was used to evaluate the different physical conditions experienced by the prototypes during manufacture and how these influence the optical performance. The selected designs satisfied the mass and surface displacement criteria of the prototype and were adapted to either the conventional or additive manufacturing process. This paper will present the prototype design process, substrate manufacture, optical fabrication, and an interferometric evaluation of the optical surfaces comparing the conventional and additive manufacturing processes.

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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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Towards understanding and eliminating defects in additively manufactured CubeSat mirrors

Cited by 4 publications

References 17 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

Lightweight, aluminum, mirror design optimization for conventional and additive manufacturing processes

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

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