Drying and Curing
VCSEL systems can be used for drying and curing processes of surfaces, paints, coatings and thin films. As an example of a high speed drying application, a VCSEL line heating module has been successfully integrated into an offset printing system for in-line ink drying [3]. In another application, fast curing of coating layers on metal sheets has been successfully demonstrated.
Plastics and Composites
The power density of VCSEL heating modules is sufficient to melt plastic materials at high speed. Examples of related industrial processes are forming of plastic parts and joining of parts by plastics welding. Also treatment of thermally melting glues can be done on various surfaces with a high processing speed.
thermal treatment
needed in various composite manufacturing processes. As an example, in a fast carbon fiber placement process, heat is applied at the laying head to attach the fibers or tapes on the surface and thereby enabling a stable build-up of the composite layers (Fig. 6).
VCSEL heating modules offer an attractive alternative to the currently used gas flames, halogen lamps or fiber coupled lasers with complicated beam forming optics or scanners. Very compact source heads are possible, delivering high power density in configurable and controllable radiation profiles.
Simulation of fiber tape heating with a time-dependent 3D-model has been done with an IR module power of 400 W per cm heating width – resembling an area module like shown in Fig. 3 – with a rectangular heat input profile of 40 mm length and a carbon fiber tape of 6 mm width and 0.2 mm thickness.
The results (Fig. 6) are confirming the application potential. For a processing speed of 30 m/min, a maximum temperature of 300 °C is reached, which is already more than enough in this application.
For applications, where materials need to be structurally modified at high temperature, the high energy density delivered by the VCSEL heating technology enables new solutions.
High power VCSEL systems define a new generation of industrial heating systems, where thousands of individual micro-lasers irradiate each point on the work piece, combining the ease of use and the robustness of LEDs with the brightness and efficiency of lasers. Scalable systems are available based on standard building blocks, combining customization with economy of scale. Assembly technologies have been derived from the LED industry, which has since long eliminated weak links. Therefore high power VCSEL systems are set to become exceptionally robust and reliable. The systems can be tailored to the application with no or simple optics. They enable an unprecedented dynamic control of the spatial heating profile and thereby help to realize a truly “Digital Thermal Processing”, where flexible, automatically controlled processes are replacing experience-based machine settings and tedious ramp-up procedures. VCSEL systems will be used in many applications which are not using lasers today but rely on lamps or ovens. The concepts presented in this article make the transition to solid state technology with full digital control, and thereby help to drive digitization of manufacturing technology.
