‘Colossal’ 3D Printer Benefits from High-performance Data Processing
TwinCAT 3 Plastic Processing Framework for extruder control and TwinCAT CNC boost additive manufacturing
Colossus is a startup in Limburg, Belgium, whose name says it all: The company possesses one of the largest transportable plastic 3D printers. It was developed by the Colossus team in cooperation with machine builder IMA in Houthalen, Belgium. 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 as the raw material, which 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-catch." To ensure that event attendees experience the excitement of 3D manufacturing live, the products must be created quickly – much faster than standard technologies currently allow. 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.
3D printing large objects requires large quantities of data
The drive control data for the linear portal is determined in two steps: First, G-code is generated from the 3D model of the end product. Next, the controller processes the G-code and computes the movement of the print head in space. Both computing procedures require high processor power.
The team at IMA, including Project Engineer Dries Daniels, Senior Automation Engineer Chris Briers and Hardware Engineer Thomas Voets, 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 more than 150 pounds (70 kg). Because of this, however, an additional calculation procedure is required to convert the correct X and Y coordinates into the corresponding data for the toothed belt drive.
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.
Using open control platform benefits 3D printer
As an open platform, PC-based control from Beckhoff was chosen for printer control. "It was clear from the very start that we needed system openness so that all components can communicate with one another," says Briers. One of the components is the heating zone control of the extruder – IMA utilizes the TwinCAT 3 Plastic Processing Framework software for this purpose.
"The extruder has six heating zones with three-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,” Briers explains. “A shut-off nozzle is used to start and stop the melt flow. This is a motorized valve, which is used to control the flow rate. The operation of this valve represents a disturbance variable for the temperature controller, which has to be compensated for."
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. The users must be able to adjust the corresponding parameters themselves.
Extrusion and CNC software libraries simplify implementation
The solution developed by IMA relies on a C6030 ultra-compact Industrial PC as well as three double actuators and one single actuator implemented via AX5000 Servo Drives. The visualization program is written in .NET so that the visualization layout can easily adapt to customer requirements.
The control software can read 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. G-code processing is a typical CNC function and, like the heating control of the extruder, is available as a library built into TwinCAT. These libraries reduce the implementation of extremely complex tasks to the simple parameterization of available functions. The TwinCAT 3 Plastic Processing Framework (TF8540) controls the temperature of the extruder, and the control parameters are determined automatically (auto-tuning). With the help of these optimized parameter settings, fast heating with low overshoot is possible.
To read out the temperatures of the individual zones and to control the heating and cooling elements, the extruder was equipped with IP67 EtherCAT Box I/O modules. A TwinSAFE Terminal is used to monitor the pressure in the extruder to ensure safe operation.
The operator interface is highly important to optimally convey the possibilities of 3D printing to the public. IMA chose the CP2912 multi-touch Control Panel with a 12-inch display as the visually appealing hardware for that purpose.
Impressive printing speed
The 3D printer from Colossus is an incredible device in every respect and delivers astounding results. Its creative design enables optimal use of available space inside the shipping and display container. 3D-printed parts with dimensions of up to 2.72 x 1.25 x 1.5 m can be manufactured. The printer also boasts an impressive output capacity of up to 15 kg per hour. A sufficiently high resolution can be achieved with a nozzle size of 2-8 mm. The printed products are ready-for-use right away, depending on the desired finish. If necessary, various postprocessing techniques can be used to create different surface qualities.
The Colossus additive manufacturing machine has seen great success since it debuted in 2018. As a result, more of these “colossal” large-format 3D printers continue to be implemented to manufacture different products on an industrial scale.
Ready to boost your additive manufacturing equipment with New Automation Technology? Contact your local Beckhoff sales engineer today.
Paxton Shantz is the Digital Manufacturing Industry Manager for Beckhoff Automation LLC.