The material used by the robots must exhibit certain properties, strength, bonding strength, low cost and curing time. Curing time is particularly crucial to allow the robot to travel on top of layers previously printed whilst maintaining structural integrity. For the final structure we use a mix of 40% Axon Easymax two component polymer, together with 60% marble powder. Each layer is 6mm high and 16mm wide. The layers are bonded together becoming a uniform shell when cured. Shell curvature can reliably reach up to 90 degrees with a 30cm radius. It is also possible to increase the percentage of marble powder without loosing mechanical properties. However as the viscosity of the material increases the amount of pressure needed to move it through pipes also increases, which in turn makes control over material flow harder.
After mixing the marble powder with polymer component A and B, each are stored separately in sealed drums. These mixed material can be stored up to a month reliably provided the powder is without moisture when mixed.
When printing on site we utilised a professional two part polymer extruder. It was extruded a the ration 1:1 through high pressure pipes, attached to a custom mixing block which in turn connects the disposable static mixer nozzle. The nozzle is connected to the robot and curing in 2-3 mins, which can be accelerated chemically or by using heat.
The extruder is also mobile, considered “the fourth robot” it supplies material, power, controllers, heater control panel and extruder flow control panel. The fourth robot follows the small robots while printing demonstrating two levels of mobility within the system.
The images included in this document may show differences due to the prototyping that was constantly evolving the system.
We have tried to make the robots as open as possible by sharing the specifications within this scientific paper.
The project has also featured in a number of publications, see below for further information.
Project by: Institute of advanced architecture of Catalonia
Sponsored by: SD Ventures