CNC Design recently completed a project with Witteveen+Bos to develop and supply a 3D concrete printing system for construction in Singapore. The system is South-East Asia’s largest 3D printer.

As Singapore’s public housing authority, the Singapore Housing & Development Board (HDB) is responsible for the development of 80% of the housing in the island city-state. There is a great demand for housing, and 3D concrete printing could help to speed up the housing development task that HDB faces.

On 16 September 2019, HDB declared South-East Asia’s largest 3D printer for construction operational. The Virtual Smart Factory (VSF) 3D Concrete Printing System is capable of printing concrete components up to 9m long, 3.5m wide and 3.8m tall. The project was a joint effort involving Robin Village Development, Nanyang Technological University, Witteveen+Bos and CNC Design.

Witteveen+Bos is an independent engineering consultancy that services clients in water, infrastructure, environment and construction projects.

Witteveen+Bos engaged CNC Design for the development of an advanced six-axis gantry robot as part of the 3D Concrete Printing System. This is now operated for HDB by Witteveen+Bos. CNC Design is an Australian-owned company established in Melbourne in 1984, with core competencies in machine tools, production machinery and associated motion control products.

The project saw CNC the two companies successfully combine their respective fields of expertise: CNC Design’s machine tool and industrial automation knowledge; and Witteveen+Bos’s experience in the use of 3D printing in concrete engineering. The result is a 3D printing system that is customised to HDB’s requirements. It includes full turnkey solutions with design, engineering, installation and delivery of the fully integrated system, with all the electrical and mechanical parts designed to ensure efficient set-up and easy operation.

CNC Design was responsible for the delivery and installation of the turnkey system. Witteveen+Bos provided on-site training for the client’s staff, with detailed knowledge of 3D concrete printing technology, settings and software. CNC Design’s presence in Australia and South-East Asia, including Singapore, Thailand and Malaysia, together with Witteveen+Bos’ Singapore location, will ensure ongoing local support in these regions.

Printing in concrete

During the last few years, Witteveen+Bos has been involved in various innovative R&D projects in Singapore, such as the ‘Development of Additive Manufacturing Technology for Construction’ and the ‘Smart Integrated Construction System’ for the HDB.

Currently, the design and fabrication of concrete building elements using the conventional method of precast production is time-consuming and requires high labour content. In addition, the moulds used in construction typically end up being discarded, resulting in material wastage.

Construction using 3D printing, on the other hand, combines digital Building Information Modelling (BIM) technology with additive manufacturing techniques to allow free-form construction without the need for moulds or forms, reducing the environmental burden of material waste. The method also opens up new opportunities for creating geometric forms that would be near impossible to create with traditional methods.

The Virtual Smart Factory system

The basis for the 3D Concrete Printing System is CNC Design’s VSF concept. The VSF concept has been applied to machining, handling and additive manufacturing, not only for concrete, but also for high-density wax (used for making GRC Panel moulds) and composite thermoplastics such as ABS with carbon-fibre.

Using Güdel three-axis Cartesian gantry modules as the platform for the VSF means CNC Design has a well proven system with high accuracy and scalability to very large sizes. The ability to add additional bridges (additional and independent X, Y and  Z axes) allows unlimited flexibility from a single machine, e.g. placement of material between print layers or surface milling.

The Siemens SINUMERIK 840Dsl flagship CNC control system is well suited to the VSF-Concrete system with its ability to handle multiple technologies and multiple operations from a single system. Technology functions such as five and six-axis machining, multi-channel operation and velocity- dependent process control, provide an advanced CNC system that also scales to suit the application.

Proving the concepts

Shortly before the 3D Concrete Printing System’s operational date, the system was visited by Lawrence Wong, Singapore’s Minister of National Development; and Cheong-Chua Koon Hean, the CEO of HDB. They were shown a room-sized 3D-printed component measuring about 11sqm (3.6m long and 3m wide and 2.75m high), produced in 13 printing hours during successful trials of the new system.

For Witteveen+Bos, this milestone proves the viability of its efforts in the field of 3D printing for construction. Witteveen+Bos has been working as one of the pioneers in 3D concrete printing since 2015. As a frontrunner in this area, it has paved the way for the first 3D-printed pilot projects around the world, such as the first 3D printed structural bridge, and the first liveable 3D printed houses.

The 3D Concrete Printing System brings together CNC Design’s core knowledge of machine tool and industrial automation, based on Siemens Sinumerik CNC technology & Güdel Cartesian gantries, with Witteveen+Bos’s knowledge of 3D printing for and the related software elements.