The behavior of gypsum-bonded investment in the gold jewelry casting process

Phetrattanarangsi, Thanawat; Puncreobutr, Chedtha; Khamkongkaeo, Atchara; Thongchai, Chonnakan; Sakkomolsri, Burimpak; Kuimalee, Surasak; Kidkhunthod, Pinit; Chanlek, Narong; Lohwongwatana, Boonrat

doi:10.1016/j.tca.2017.09.008

Cited by 22 publications

(12 citation statements)

References 18 publications

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“…Deviations between the PLA pattern and the final A356 lattice structure (Step II) can be attributed to dimensional changes that occur during two distinct processing stages; (i) forming the investment cast: due to the expansion of the investment gypsum mold during its curing which involves the loss of water and the transformation of gypsum from α (cristobalite) to β (quartz) 75 ; and (ii) during/after A356 melt casting: due the contraction of the A356 alloy during the solidification and subsequent cooling 76 , 77 . The net result is that the final A356 cast samples tend to display slightly larger dimensions than the PLA samples.…”

Section: Resultsmentioning

confidence: 99%

Macro-, meso- and microstructural characterization of metallic lattice structures manufactured by additive manufacturing assisted investment casting

Carneiro

Rawson

Puga

et al. 2021

Sci Rep

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Cellular materials are recognized for their high specific mechanical properties, making them desirable in ultra-lightweight applications. Periodic lattices have tunable properties and may be manufactured by metallic additive manufacturing (AM) techniques. However, AM can lead to issues with un-melted powder, macro/micro porosity, dimensional control and heterogeneous microstructures. This study overcomes these problems through a novel technique, combining additive manufacturing and investment casting to produce detailed investment cast lattice structures. Fused filament fabrication is used to fabricate a pattern used as the mold for the investment casting of aluminium A356 alloy into high-conformity thin-ribbed (~ 0.6 mm thickness) scaffolds. X-ray micro-computed tomography (CT) is used to characterize macro- and meso-scale defects. Optical and scanning electron (SEM) microscopies are used to characterize the microstructure of the cast structures. Slight dimensional (macroscale) variations originate from the 3D printing of the pattern. At the mesoscale, the casting process introduces very fine (~ 3 µm) porosity, along with small numbers of (~ 25 µm) gas entrapment defects in the horizontal struts. At a microstructural level, both the (~ 70 μm) globular/dendritic grains and secondary phases show no significant variations across the lattices. This method is a promising alternative means for producing highly detailed non-stochastic metallic cellular lattices and offers scope for further improvement through refinement of filament fabrication.

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Section: Resultsmentioning

confidence: 99%

Macro-, meso- and microstructural characterization of metallic lattice structures manufactured by additive manufacturing assisted investment casting

Carneiro

Rawson

Puga

et al. 2021

Sci Rep

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“…A minimum temperature combination of 250 °C for the mold and 700 °C for the casting must be used to guarantee the complete filling of the samples. It is suggested that in near complete casting It is known that during its thermal cycle, the plaster releases its water content losing mass, however, the overall mold can suffer an expansion due to the αto βtransitions in the cristobalite (5.7% in volume) and quartz (4.3% in volume) components of the plaster [64]. Additionally, aluminum alloys suffer from considerable shrinkage and linear contraction during solidification [65,66].…”

Section: Discussionmentioning

confidence: 99%

Thin-Rib and High Aspect Ratio Non-Stochastic Scaffolds by Vacuum Assisted Investment Casting

Carneiro¹,

Puga

Peixinho³

et al. 2019

JMMP

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Cellular structures are a classic route to obtain high values of specific mechanical properties. This characteristic is advantageous in many fields, from diverse areas such as packaging, transportation industry, and/or medical implants. Recent studies have employed additive manufacturing and casting techniques to obtain non-stochastic cellular materials, thus, generating an in situ control on the overall mechanical properties. Both techniques display issues, such as lack of control at a microstructural level in the additive manufacturing of metallic alloys and the difficulty in casting thin-rib cellular materials (e.g., metallic scaffolds). To mitigate these problems, this study shows a combination of additive manufacturing and investment casting, in which vacuum is used to assist the filling of thin-rib and high aspect-ratio scaffolds. The process uses 3D printing to produce the investment model. Even though, vacuum is fundamental to allow a complete filling of the models, the temperatures of both mold and casting are important to the success of this route. Minimum temperatures of 250 °C for the mold and 700 °C for the casting must be used to guarantee a successful casting. Cast samples shown small deviations relatively to the initial CAD model, mainly small expansions in rib length and contraction in rib thickness may be observed. However, these changes may be advantageous to obtain higher values of aspect ratio in the final samples.

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“…A gypsum-bonded investment material with a binder that contains calcium sulphate hemihydrate was used. Gypsum-bonded investment is commonly used in silver and [16] states that this can cause several defects such as gas porosity from the decomposition of gypsum. Other authors [17] [18] [19] [20] in their studies finds that the decomposition of calcium sulphate occurs at a high temperature resulting in the discharge of sulphur dioxide gas into the mould and causing gas porosity at the surface of the metal.…”

Section: Investment Materialsmentioning

confidence: 99%

Study of Investment Casting Process For 3D Printed Jewellery Design

Abisuga

Doran²,

Beer

2022

MATEC Web Conf.

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Manufacturing processes are increasingly complex with the growing demands of advanced technology in the production processes, especially in the handicraft industry. The complex jewellery designs are complicated to be produced by hand, considering the international demand and dynamics in the jewellery industry. However, advanced production processes and 3D printers are changing the way jewellery designers and manufacturers work and making it easier to produce quality products with fewer production and labour input hours. This study examines the investment casting process of 3D printed design as an option for jewellery manufacturing. The research aims to access jewellery manufacturing processes and its technology application by using trending 3D printing as a rapid prototype. It used the design and production process of 'OneCent Africa' as a case study to describe the process in the investment casting of jewellery products. The investment casting was conducted by prototyping, and the lost wax jewellery casting stages using the vacuum casting machines and burnout oven, with the casting process monitored in parts. This research results led to a better understanding of the experimental casting outcomes and described the potential for the future technological development of jewellery businesses.

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The behavior of gypsum-bonded investment in the gold jewelry casting process

Cited by 22 publications

References 18 publications

Macro-, meso- and microstructural characterization of metallic lattice structures manufactured by additive manufacturing assisted investment casting

Macro-, meso- and microstructural characterization of metallic lattice structures manufactured by additive manufacturing assisted investment casting

Thin-Rib and High Aspect Ratio Non-Stochastic Scaffolds by Vacuum Assisted Investment Casting

Study of Investment Casting Process For 3D Printed Jewellery Design

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