Since its concept was proposed in the early 2010s, the fourth industrial revolution is rapidly going on and will transform the world considerably. According to a report by McKinsey & Company [1], Additive Manufacturing (AM, also called 3D printing) is the core of digital-to-physical transfer which is one of the four driving forces of Industry 4.0.
3D printing has been implemented in many industries, such as aerospace & defence, medical & dental, and automotive, since its advent [2]. It keeps evolving very rapidly and provides solutions to manufacturing that are approaching what traditional manufacturing techniques can offer. More and more companies around the globe start to realise its capabilities and potential to change the world. As per Global EY Report 2019 [3], participants in the 3D printing market can be classified into five categories, namely systems manufacturer accounting for 38% of the market share, service providers (34%), material producers (16%), software producers (8%), and 3D scanning (4%).
In the era of Industry 4.0, 3D printing promises to make a marked difference. Fig. 1. shows the estimated development of the market size of 3D printing by technology in North America, demonstrating a steady increase. Furthermore, according to statistics, in 2020 the worldwide market size of 3D printing has reached 13.78 billion USD, while it is predicted to expand at a CAGR of 21% over the next eight years [4].

There are several reasons why 3D Printing will become more and more ubiquitously applied in industries.
- the ever-lowering price of 3D printer and printing materials [5], making it more affordable, even for family.
- The maturity of technologies. For example, the availability of standardised printing materials with known properties and the speed-up of the 3D printing production process.
- AI-driven performance optimisation. By processing and learning large numbers of video streams collected from millions of ongoing 3D printing work around the world, the combination of printing parameters is optimised continuously, giving rise to material saving and improved product quality. Moreover, printing strategies can be tuned in real-time to remedy defects in previously deposited layers thanks to the adoption of computer vision technology. This further contributes to improved printed results.
- Factories featured by mass production triumphed in the third industrial revolution, whereas in industry 4.0, companies that can cater to bespoke demands of their customers at a lower cost can survive and thrive.
Based on the author’s knowledge in 3D Printing, the gaps that exist in industries are more powerful parametric 3D modelling software (for the ease of later stage modification and reuses) and intelligent slicing software demanding fewer professional knowledge and operations from the user. Therefore, productivity can be improved, and designers can focus entirely on their creativity.
Although currently, 3D printing is still an expensive solution in many applications in different scenarios, it won’t take long before it reaches its breakeven and realises its full potential.

Building structure 3D printing promises to bring a cascade of benefits to the society, including reduced risks, material saving, design freedom improvement, and construction period reduction, as compared with convention construction methods, shown in fig. 2. Ultimately, the cost of constructing buildings can be reduced. It also showcases a higher level of technology of a country and a developed society.

The obstacles to large-scale engineering application are the reinforcement and 3D printing inherent issues. Given concrete is brittle in nature and it lacks tensile strength, it is usually strengthened by steel rebar. The integration of the reinforcement with the concrete 3D printing process leaves much to be desired. Also, because of the layer-by-layer deposition manner, there are many voids between filaments, leading to high porosity. This weakens the mechanical properties significantly. Solutions to overcoming these 3D printing inherent defects are thus crucial.

We are aiming to incorporate machine learning and computer vision into building structure 3D printing to optimise the quality of printed structural components and achieve an auto-adaptive 3D printing system. By identifying and remedying inherent defects inside printed results, their mechanical properties are projected to be enhanced considerably. With the help of machine learning, the performance of large-scale on-site 3D printing is to be advanced by taking temperature and moisture changes into consideration, given on-site 3D printing construction is subject to changing conditions, such as temperature fluctuation and rainy days.
Reference
[1] https://www.mckinsey.com/business-functions/operations/our-insights/manufacturings-next-act
[2] https://www.grandviewresearch.com/industry-analysis/3d-metal-printing-market
[3] https://assets.ey.com/content/dam/ey-sites/ey-com/en_gl/topics/advisory/ey-3d-printing-game-changer.pdf?download
[4] https://www.grandviewresearch.com/industry-analysis/3d-printing-industry-analysis
[5] https://www.ey.com/en_gl/advanced-manufacturing/how-the-future-of-3d-printing-is-taking-shape
[6] https://www.3dnatives.com/en/3d-printed-house-companies-120220184/
[7] https://www.concreteconstruction.net/how-to/construction/a-steel-composite-alternative-to-the-reinforced-concrete-core_c
[8] Jiang, S., Liao, G., Xu, D., Liu, F., Li, W., Cheng, Y., … & Xu, G. (2019). Mechanical properties analysis of polyetherimide parts fabricated by fused deposition modeling. High Performance Polymers, 31(1), 97-106.