Glass casting displays great forming potential allowing for the realisation of three-dimensional glass elements of virtually any shape and size, as showcased in glass art. Disposable mould technology seems to be ideal for the fabrication of such customised and complex geometries, including for architectural and structural cast glass components deriving from structural topology optimization, since it offers great shape freedom and cost effectiveness. However, currently, glass casting on disposable moulds faces the major drawback of a resulting rough and opaque glass surface quality, requiring considerable post-processing to yield a glossy, smooth surface. This in turn results in a compromised dimensional accuracy and on increased time and production costs. If the surface remains unprocessed, it can greatly affect not only the visual but also the mechanical properties of the cast glass element. Aim of this research is to improve the surface quality of complex glass components cast in disposable moulds, directly during demoulding, reducing in this way the need for post-processing. To achieve this the research focuses on exploring ways to pre-process disposable moulds. In specific, the research focuses on series of kiln-cast laboratory experiments at various maximum firing temperatures / annealing schedules involving the use of two different types of disposable moulds, 3D-printed sand moulds and silica plaster moulds (Crystalcast®), and the application of refractory coatings, coating combinations and protective layers. The experimental work conducted thus far indicates that the best results are obtained at the lowest maximum temperature tested (870 °C), with the combination offering the best finishing quality to be a synthetic (ceramic) sand mould coated with Crystalcast® and Zirkofluid® (6672, 1219). Scaling-up of the kiln-cast prototypes unveils a complex correlation between the maximum dwell time at the maximum firing temperature and the casting effectivity/ performance of mould materials and coatings.@en

Recent research at TU Delft has highlighted the potential of using structural Topology Optimization (TO) for designing large monolithic cast glass structures of maximized stiffness with minimal mass. The mass efficiency of these structures results in considerably shorter annealing times and, consequently in improved manufacturability in terms of time, energy and cost efficiency. Nonetheless, the geometrical complexity and customization of the resulting forms renders them challenging in terms of fabrication. Exploring the manufacturability of such intricate glass structures, in this paper we discuss the different possible fabrication methods for three-dimensional glass structures of complex and customized geometries, via a review of existing literature, experimental work and prototyping. Specifically, with the aim of addressing all possible manufacturing solutions, we look into the following fabrication methods: (i) casting in disposable moulds; (ii) waterjet cutting and lamination of float glass panes and; (iii) additive manufacturing of glass. We assess these methods based on a set of criteria linked to the structural performance, visual quality, fabrication limitations and sustainability. Accordingly, we discuss the potential, challenges and practical limitations of each fabrication method for real-world applications of TO glass structures. Subsequently, we propose the integration of alternative constraints into the TO formulation, so that customized TO tools that better reflect each fabrication method can be created.@en