Colossus is a startup enterprise in Belgium, and possesses one of the largest transportable plastic 3D printers on the market. It was developed in cooperation with machine builder IMA. The printer’s trailblazing controls come from Beckhoff and not only control the traversing axes in the machine, but also the temperature of the extruder in the print head.
Colossus plans to manufacture large functional or decorative objects such as outdoor furniture and ornaments with a new 3D printer that processes recycled plastics, and this creates further special requirements. In addition, the 3D printer will be installed in a container and transported to trade shows and festivals as an eye-catcher. The products must therefore be created quickly – much faster than standard technologies. In short, Colossus tasked machine manufacturer IMA with a very ambitious project.
The recycled materials are processed using the Fused Granular Fabrication (FGF) process, in which a plastic granulate is melted in an extruder and the end product is created by applying layer after layer of the material. In this application, the extruder’s print head is moved through space by a special linear portal.
The drive control data for the linear portal are determined in two steps. First, G-code is generated from the 3D model of the end product. The controller processes the G-code and computes the movement of the print head in space. Both of these computing procedures require high processor power.
The IMA team developed an XYZ portal as the drive for the 3D printer. Toothed belts drive both the X- and Y-axes so that the Y-axis does not require a motor. The goal was to save weight, because the extruder alone weighs 70 kg. The XYZ portal itself is mounted on four spindles, each equipped with its own drive. In this way, the printing plane can be kept in perfect parallel to the plane of the X and Y-axis.
PC-based control from Beckhoff was chosen for the control of the printer. One of the components is the heating zone control of the extruder. IMA utilises the TwinCAT 3 Plastic Processing Framework software for this purpose. The extruder has six heating zones with 3-point control. Each zone has a heater band and a fan for cooling. To achieve a stable process, these devices need to be precisely controlled. A shut-off nozzle is used to start and stop the melt flow. This is a motorised valve, which is used to control the flow rate. “The extruder operates with a constant throughput. This means the movement of the print head must be controlled in relation to the geometry of the end product. Users must be able to adjust the corresponding parameters themselves.
The solution developed by IMA is based on a C6030 ultra-compact industrial PC as well as three double actuators and one single actuator implemented via AX5000 servo drives. The visualisation program is written in .NET so that the visualisation layout can easily adapt to the customer’s wishes.
The control software can read in and process large quantities of data in G-code format. TwinCAT CNC takes care of the interpolation and kinematic transformation of the virtual X and Y-axis to the A and B-axis of the XYZ portal. The temperature of the extruder is controlled with the TwinCAT 3 Plastic Processing Framework. The control parameters are determined automatically. With the help of these optimised parameter settings, fast heating with low overshoot is possible.
In order to read out the temperatures of the individual zones and to control the heating and cooling elements, the extruder is equipped with IP67 EtherCAT Box I/O modules. The operator panel is regarded as highly important to optimally convey the exciting possibilities of 3D printing to the public. IMA chose the CP2912 multi-touch control panel with 30 cm display as the visually appealing hardware for that purpose.
The 3D printer from Colossus is a superlative device in every respect and delivers astounding results. Its creative design allows the best possible use of available space inside the shipping and display container. The printer also boasts an impressive output capacity of up to 15 kg per hour.
Colossus presented the first printer at multiple events and trade shows in 2018. There was great interest in the 3D giant and its new method of recycling. More of these printers will be implemented to manufacture products on an industrial scale in the future.
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