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The 3D-printing technology

3D-printing: Revolution in construction.

 

 

Our supplier in terms of 3D-printers is the Danish company COBOD and specifically their BOD2. It is a gantry printer consisting of several modules. The number of modules is customizable, depending on the needs of each construction project.

The printer consists of X, Y and Z axis and modules with a respective length of 8.2ft, which can be flexibly extended on each of the three axes. The print head can move left and right along the X-axis. The X-axis itself, and thus the printhead, moves forward and backward along the Y-axis, which in turn moves downward and upward along the Z-axis. This allows the printhead to move along the three axes on the fixed calibrated frame.

The gantry system is suitable for in-situ concrete projects as well as for the production of 3D-printed precast parts. The printer's gantry system allows us to avoid permanent repositioning and recurring calibration of the printer. This in turn leads to cost and time savings compared to using a 3D printer with a robotic arm.

 

The print head itself has a replaceable nozzle system and tangential control, which makes it possible to even print smooth surfaces. However, there is another interesting feature of the printer, and that is the surface monitoring. The printer independently measures the distance to the foundation and collects the data in a "height map". When printing begins, the first layer, the printer can automatically compensate for the unevenness layer by layer until everything is level.

With the BOD2 of our rental fleet, we can print buildings with a maximum floor area of 2,185 sqft and three floors. The largest printer built to date, on the other hand, can print up to a footprint of 3,229 sqft. Nevertheless, both have something in common: the maximum dimension of the BOD2 is 49.21 ft wide, 32.81 ft high and as long as you like. These dimensions require the BOD2 to be firmly bolted to the floor plate or concrete blocks, on the one hand, and different erection and dismantling time, on the other hand. To illustrate the time with an example: A printable area of 39.37 ft width, 55.77ft length and 86.11sq ft height requires about 12 hours.

 

To allow workers to safely and securely perform manual tasks during printing, we do not print at the maximum speed of 3ft/s, but at a speed of 0.82ft/s. The printer offers tremendous flexibility in height and width, allowing for a layer height of 0.033ft to 0.09ft and a layer width of 0.09ft to 0.66ft.


The BOD2 is CE certified and features IP67-rated cabling and galvanized steel trays. Now the question remains, what material can be used? The answer is: any, locally available, 3D-printable mortar or concrete can be used that has a grain size of up to 0.026 ft. For our projects, for example, we used material from HeidelbergCement and Lafarge-Holcim.

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