CAM for Laser Material Processing
Computer Assisted Manufacturing (CAM) plays an important role in the process chain for Laser Material Processing. Based on a digital model of the component NC programs for the control of the mechanical axes and the optical systems are generated. For Laser Metal Deposition (LMD) processes Fraunhofer ILT developed the software “LMDCAM“. This software is a powerful tool path planning instrument for repairing and additive manufacturing of components. It is optimized for working with large data files (e. g. triangulated data acquired by a measuring device). The user is able to interact with all entities (like CAD data and the tool path) and thereby complex and individual tasks can be solved. After generating tool paths the resulting machine movement can be checked for collisions or exceeded axis velocities. For this task the software includes a build-in machine simulation tool. Using the included programmable post processor tool paths can be exported as NC programs which can also support multi-axes systems (e. g. robots).
For laser micro structuring galvanometric laser scanners for laser beam deflection and short pulse laser sources are used. Compared to LMD laser micro structuring is a subtractive manufacturing process where the material is ablated locally. Fraunhofer ILT developed the software “SliceGen“ specially adapted to the laser structuring process. A CAD model is filled with tool paths layer by layer. Each layer can be tiled to the limited working volume of the laser scanner. The tiles can be distributed randomly to avoid visible boundaries. The software is also able to generate tool paths for form correction by measured data. For this application the tool paths for removing the surplus volume are calculated based on the desired and current topography.
For laser polishing Fraunhofer ILT developed the software “TP4“ to convert data, generated by a conventional CAM software (for finishing milling), into tool paths which are suitable for the laser polishing process. As in laser structuring, this process also uses a laser scanner for fast laser spot positioning. Therefore the required total movement is split into two parts. The fast movement is assigned to the laser scanner while the slow movement is assigned to the slower mechanical axis system (usually a 5-axis system). The software calculates the superposed movement and generates separate NC programs for the laser scanner and the mechanical axes. Machine programming in work piece coordinates is also supported which allows the usage of a measuring probe. Furthermore several process strategies are implemented in the software to ensure constant process conditions also on curved surfaces. To meet the various requirements for different applications and setups the software has access to a database where many process parameters for different materials, applications and kinematics are stored.
Control of Galvanometric Laser Scanners
For many laser based processes it is advantageous to rapidly guide the laser beam focus over the surface with the use of galvanometric laser scanners with axes of very low inertia. In order to control these scanners, special controller systems with low cycle times are used. Many different software solutions for controlling laser scanners, which are often restricted for laser marking applications, are commercially available.
Fraunhofer ILT developed a flexible and process independent software solution for controlling laser scanners. The user can access a scripting module to extend the software for the taskspecific generation of laser paths. The resulting scanner movement is previewed in a 3D view. Different scanner parameters (like velocity or laser power) can be visualized color-coded. The software also contains a remote interface which allows to control the software over LAN. Thereby the software can be integrated in an existing environment (e.g. a CNC controller). This interface also allows remote executing of a script with specific parameters.
Acquiring and Processing of Topographic Data
Topographic data can be used to inspect a surface for quality assurance or for obtaining different standardized surface parameters. It also can serve as a basis for local surface processing taking the actual surface topography into account.
Fraunhofer ILT developed a set of software tools for the acquiring, processing and analysis of topographic data. The data can, for example, originate from a white light interferometer or a confocal sensor. On the basis of these tools individual tasks can be fulfilled. This comprises the automated measurement of multiple laser processed surfaces or parts. The data is filtered and analysed for statistical surface characteristics (e. g. roughness or PSD spectrum).
Range of Services
- Development of CAM-NC data chains and algorithms for process optimized tool path calculation
- Development, integration, assembly and testing of control setups for Laser Material Processing
- Development of HMI (Human Machine Interface) for the control of laser machines and laser scanners