What should I consider when choosing a 3D construction printer?

3D construction printing has great potential to fundamentally transform construction, making it faster, more cost-effective, and more efficient – with fewer personnel. Instead of brickwork or formwork, walls are automatically applied layer by layer by a 3D printer. The technological heart of any 3D printing construction site is, of course, the printer. However, not every commercially available 3D printer can create a habitable building. A 3D construction printer must meet the following requirements:

Printing system and scalability

The first step is choosing the right printing system. Two systems have become particularly popular in the construction industry: robotic arm printers and gantry systems. Robotic arms are usually smaller and can be deployed more quickly, but their printing area is limited by the arm's reach. For larger buildings, the printer must be moved and recalibrated frequently. With gantry systems like the COBOD BOD2, on the other hand, the 3D printer is built around the printing area. A print head moves along three axes within the framework to extrude the building material. The BOD2 system is also modularly configurable and can be flexibly expanded depending on the size of the building. This means that buildings up to 13.5 meters long, 9 meters high, and a practically unlimited length are possible without having to relocate the printer.

Material compatibility

To date, 3D-printable concrete and mortar have primarily been used in 3D construction printing. Several products from various material manufacturers are already available, differing in their composition and properties. For the greatest possible flexibility, the 3D printer should be open to all materials, meaning it is not limited to specific building materials. This freedom of choice is also determined by the printer's printable grain size, i.e., the maximum size of the bricks contained in the printing material. 3D-printable building materials have the special feature of having high green strength to allow the individual layers to be stacked on top of each other while still wet. At the same time, the material must not set too quickly, as the layers must still be able to chemically bond to form a monolithic structure. A reliable process from mixing to extrusion is therefore crucial for a smooth construction process.

Print speed

A high print speed means rapid completion of the walls and is therefore an important criterion when choosing the right 3D printer. With a print speed of up to one meter per second, the COBOD BOD2 is currently the fastest 3D construction printer on the market. If manual work is to be performed in the printing area during the print run, such as inserting stability anchors and conduits, the print speed must be reduced to 25 centimeters per second. The layer times of the various printing materials must also be taken into account to ensure that the individual layers achieve the optimal properties. Based on these factors, the COBOD BOD2, for example, can produce one square meter of cavity wall in just five minutes.

Precision and flexibility

The quality of the individual layers, and thus also of the 3D-printed walls, is significantly influenced by the 3D printer. Various nozzles offer the possibility of shaping the width, height, shape, and structure of the layers as desired. The greatest control over the result is achieved with printers whose extrusion nozzles can be rotated and automatically align themselves along the print path when cornering. Nozzles with so-called flaps are also possible, in which sliding fillers smooth the printed layers during the printing process to facilitate subsequent plastering. Systems with this type of tangential control offer architects and planners complete design control. For a more consistent print image and better usability, a print head with a hopper also provides a buffer for the material feed.

Safety and durability on the construction site

3D construction printing can be used as a pure precast solution in precast concrete plants. However, in our experience, the full potential of this construction method only unfolds when used directly on the construction site. There are also a number of things to consider here. Various safety regulations must be adhered to. The COBOD BOD2, for example, is CE-certified, uses IP67-certified cabling, and galvanized steel cabling. Emergency shutdown buttons are also distributed throughout the system to make operation on the construction site as safe as possible. If you want to avoid the need for a costly enclosure, you should also ensure that the 3D printer is wind and weather-resistant and can be cleaned quickly.

User-friendliness and learning curve

At PERI 3D Construction, our goal is to empower construction companies with the technology and expertise to create buildings themselves using 3D construction printing. However, interested companies don't necessarily need robotics engineers on their team to achieve this. That's why we offer training courses where you can learn how to operate the COBOD BOD2 3D printer in just six weeks. A basic qualification as a bricklayer or reinforced concrete worker is perfectly adequate. The printer can be operated directly via a browser client on a laptop or smartphone. This allows even last-minute changes to be implemented quickly and easily. Sensor-supported assistance systems such as 3D MATCONTROL offer additional transparency and make it easier to achieve consistent results even under changing environmental conditions. The 3D models of the buildings to be printed can also be read by the slicer in any conventional CAD format. This ensures beginner-friendly use from planning to implementation.

In summary, numerous requirements are placed on the 3D printer to successfully print buildings. Similar requirements also apply to the silo mixing pump used, the architectural model, the materials used, and other aspects of the process. Yet, all of these requirements have been fully met many times to create buildings using 3D printing.

All of these requirements lay the foundation for a new way of building, one that is intended to offer the industry significantly greater speed and efficiency. The major leap in productivity that the construction industry urgently needs can hardly be achieved through slow, incremental optimizations – but only through radical rethinking, innovation, and automation. Setting high and well-thought-out standards on many fronts provides us with the basis for holistic solutions that have the potential to fundamentally transform construction.