New Calibration Method for Laser Powder Bed Systems Enables High-precision Batch Repairs

The newly developed AM.repair process enables the repair of worn or deformed components using Laser Powder Bed Fusion (LPBF). The aim is to restore these components by capturing the damaged areas using 3D scanning technology, removing the damaged areas and rebuilding the missing geometry directly onto the cut part using LPBF. This process is particularly suitable for parts with localised wear, such as blade tips in aircraft engines, and allows multiple components to be repaired simultaneously.
The main challenge in the AM.repair process is to achieve the precision required for the laser to accurately hit the component and apply the repair geometry. A significant technological issue is that the laser and the build platform operate in two independent coordinate systems. During data preparation, the component is positioned virtually in the building platform's coordinate system, while the laser is guided by an optical system that operates in a separate coordinate system. This misalignment can result in deviations of more than 1mm. While this was not a problem when producing new parts, the AM.repair process requires greater accuracy. Therefore, the laser and build platform coordinate systems must be calibrated and aligned.
Industry-standard calibration involves printing and measuring calibration patterns, achieving an accuracy of only 100 microns and taking up to eight hours. The newly developed optical calibration system achieves up to 20-micron accuracy in minutes without the use of powder. A dot pattern is lasered onto a black plate, then captured by a camera system including an LED matrix with an modulation algorithm for perfect illumination. A computational algorithm analyses the data to generate a correction matrix. This matrix modifies the input data to compensate for the offset without interfering with the LPBF system's internal control, enabling precise repairs across the entire platform and significantly improving repair accuracy and efficiency.