Controlled heating system for thermosetting composites based on laser technology
Participants:
EUSKABEA
Programme:
Sectors:
Aeronautics-Aerospace
Automation
Boiler making and metal processing
Renewable energy
Technologies:
Control and Robotics
Materials
Laser
Scope
Sectors such as automotive, rail, marine and architecture are increasingly demanding customised structures, but the shape, large size and structural requirements of their products do not enable current technologies and materials to be manufactured by additive manufacturing processes.
To address this challenge, achieving advanced materials based on thermosetting composites is proposed for this type of additive manufacturing processes. These materials are already used in the aeronautical, automotive and shipbuilding sectors. Bonding layer upon layer or layer-by-layer adhesion must be achieved. This is obtained by curing, which in the case of large parts will require sufficient heating to activate and accelerate the process efficiently and effectively.
Solution
To do so, LORTEK and EUSKABEA are developing a controlled heating system for thermosetting composites based on laser technology. Laser radiation is able to excite the composite material and heat it selectively, accelerating the curing process. Since this heating-curing process depends on the laser power applied, the temperature reached by the material needs to be measured and thus, the power supplied by the laser needs to be controlled.
Based on these premises, a system has been designed and integrated consisting on a line diode laser head (21 mm wide x 5 mm long) emitting at 808 nm (wavelength of high absorption efficiency in thermosetting composites) with a variable output power (MAX. 400 W) which allows efficient heating at high production speeds (3,000 mm/min). The temperature reached by the composite is monitored and measured by means of an infrared thermal imaging camera (7.5 - 13 µm) with high precision (160 x 120 px) and acquisition speed (128 Hz) and adaptable measuring range (-20 to + 100 °C / 0 to + 250 °C). The device also integrates a small visible camera that allows monitoring the process phenomena identifiable by computer vision techniques.
The system has achieved successful results on efficient heating of 1 and 2 mm thick beads at near real working speeds (2000 mm/min) with medium laser power (200 W). This shows there is room for improvement in the overall system performance.
In addition to applications for thermosetting plastic materials, this controlled heating system has a huge potential for other applications, such as active thermal imaging for metals, where an external excitation source is needed to heat the material up to a certain temperature in a controlled way.
