zhiguang_Reader Response_Final Draft

The Stereolithography (SLA) technique is considered to be the most prominent and popular 3D printing technology and has been used extensively worldwide (Jacobs, 1992). It was first proposed and developed by Hull (1986) and later commercialised by 3D Systems Inc. SLA is a process where liquid photosensitive resin is poured into a vat and UV light selectively polymerises the resin to create high-precision parts. SLA is capable of fabricating parts of high surface quality at fine resolutions down to the micrometre scale (Wu et al., 2016). As the most common resin 3D printing technology, SLA has gained widespread popularity for its ability to produce highly accurate, isotropic, and waterproof prototypes and end-use parts (3DEXPERIENCE Make, n.d.). Professional SLA 3D printers, such as Formlabs' Form 4, can produce walls as thin as 0.2mm, with embossed and engraved details as fine as 0.1mm and 0.15mm respectively (Formlabs, 2024a). Advances in hardware, software, and materials science have made SLA technology more affordable and accessible, transforming prototyping and production workflows across industries.

 

In the construction sector, SLA 3D printing technology offers significant potential for rapid, accurate, and bespoke manufacturing (e.g., topology-optimised structural connectors and customised building envelopes).

 

The main advantage of using SLA is the speed factor, as one of the main challenges of construction projects is the long construction period, which often exceeds the original schedule (Assaf & Al-Hejji, 2006). A major contributor to these delays is the communication challenge, as frequent design changes by architects are difficult to communicate accurately using traditional 2D drawings. In contrast, architectural models produced using SLA 3D printing technology can more visually represent design changes, reducing misunderstandings and improving communication (Formlabs, 2024a). While traditional mold making involves multiple steps (design → prototyping → mold machining → testing) and typically takes 4–8 weeks, 3D printing allows production directly from the digital model, reducing the lead time to 1–2 weeks (Singh & Singh, 2018). For example, Renzo Piano's company, RPBW, used SLA 3D printers to produce its latest model in less than 24 hours (Formlabs, 2024a), and Formlabs' latest SLA 3D printer, the Form 4, prints in as little as two hours, a significant improvement in efficiency (Formlabs, 2024b).

 

The second reason for advocating the use of SLA 3D printing technology in engineering is its high level of accuracy. The core strengths of SLA are its precision and accuracy, making it ideal for processes where shape, fit, and assembly are critical. For example, the tolerances of SLA parts are typically less than 0.05mm, ensuring smooth edges and reducing irregularities that are common with traditional manufacturing methods (3D Systems, 2023). This level of accuracy not only improves the quality of the final product but also saves time and resources by minimising the need for post-processing.

 

The third way in which the adoption of SLA printing has significantly changed the construction industry is in its ability to enable mass production without compromising individuality. Mass customisation (i.e., building products for individual customer orders rather than for stock) has been a goal of the construction industry for decades, and 3D printing technology can help build bespoke products without adding to costs (Wu et al., 2016).

 

Despite the many advantages of SLA, other 3D printing technologies such as Fused Deposition Modelling (FDM) and Selective Laser Sintering (SLS) are also used in the construction industry. Each printing technology offers unique advantages, and the choice of application usually depends on factors such as cost, print time, accuracy, and available materials. SLS has advantages over FDM and SLA for complex designs, and SLS-printed parts have excellent mechanical properties for structural components (Formlabs, 2024a). In contrast, FDM has a wider range of material compatibility (e.g., HIPS, PP, TPE, nylon, PLA, and ABS) and lower material costs ($80 to $210 per litre) compared to SLA’s light-curing resins (Wu et al., 2016). Also, because most SLA printing materials are based on photosensitive resins, they can still be affected by UV light when exposed to sunlight for long periods of time, compared to the materials used in FDM. UV rays can trigger a photodegradation reaction that can lead to yellowing of the material's colour, brittleness, and even loss of performance, making it less durable than FDM (Xometry, 2023).

 

The performance of SLA 3D printing in real-world applications depends on many factors, including print accuracy, material selection, cost control and print speed. Therefore, the construction industry needs to choose the right 3D printing technology, such as SLA, FDM and SLS, to optimise its application. With technological advances and material innovations, the development of SLA 3D printing technology has opened up many opportunities for the construction industry (e.g., significant reduction in CO2 emissions (UNEP, 2022)), but there are still many challenges to its wider application, including suitability for large-scale construction projects, meeting the need for mass customisation, and controlling the lifecycle costs of construction products. Currently, the application of SLA 3D printing technology in the construction industry is still in the exploratory stage, and many customised applications have yet to be fully validated. However, by gradually overcoming technical bottlenecks, this technology is expected to revolutionise the construction industry, driving it in a smarter and more sustainable direction, and ultimately realising a more efficient and environmentally friendly approach to building production.

(Used ChatGPT to check my grammar)

 

References

1. 3D Systems. (2023). Stereolithography (SLA) 3D printing technology. https://www.3dsystems.com/stereolithography
2. 3DEXPERIENCE Make. (n.d.). SLA stereolithography 3D printing services. https://www.3ds.com/make/service/3d-printing-service/sla-stereolithography
3. Assaf, S. A., & Al-Hejji, S. (2006). Causes of delay in large construction projects. International Journal of Project Management, 24(4), 349–357. https://doi.org/10.1016/j.ijproman.2005.11.010
4. Formlabs. (2024a). 3D printing architectural models. https://formlabs.com/asia/blog/3d-printing-architectural-models/
5. Formlabs. (2024b). The ultimate guide to stereolithography (SLA) 3D printing. https://formlabs.com/asia/blog/ultimate-guide-to-stereolithography-sla-3d-printing/
6. Hull, C. W. (1986). Apparatus for production of three-dimensional objects by stereolithography (U.S. Patent No. 4,575,330). U.S. Patent and Trademark Office. https://patents.google.com/patent/US4575330/en
7. Jacobs, P. F. (1992). Rapid prototyping & manufacturing: Fundamentals of stereolithography. Society of Manufacturing Engineers.
8. Singh, R., & Singh, S. (2018). Time and cost comparison between rapid casting and conventional sand casting. Journal of Manufacturing Processes, 34, 307–315. https://doi.org/10.1016/j.jmapro.2018.04.017
9. United Nations Environment Programme (UNEP). (2022). 2022 global status report for buildings and construction. https://www.unep.org/resources/publication/2022-global-status-report-buildings-and-construction
10. Wu, P., Wang, J., & Wang, X. (2016). A critical review of the use of 3D printing in the construction industry. Automation in Construction, 68, 21–31. https://doi.org/10.1016/j.autcon.2016.04.005
11. Xometry. (2023, December 4). 3D printing: SLA vs. FDM. https://xometry.pro/en-eu/articles/3d-printing-sla-vs-fdm/