Laser net shape manufacturing using an adaptive toolpath deposition method

Laser net shape manufacturing (LNSM) is a laser cladding based technology which can prototype and repair three-dimensional components with complex geometries. Manufacturing macro-parts with small feature size usually requires a small laser beam and slow deposition rate, which sacrifices the manufacturing speed when one contemplates fabricating entire parts. Depositing materials adaptively according to the geometric features has the advantages of increasing the overall deposition speed, improving dimensional accuracy, and saving raw materials. This paper presents a geometry-based adaptive toolpath deposition method for prototyping or repairing aircraft engine compressor airfoils and blisk airfoils, where cross-section areas are slim and long. For these parts, the thickness varies from sub-millimeter to several millimeters. Based on processing transfer functions, deposition toolpaths are designed with predetermined bead width, height, and overlap ratio. Adaptive deposition bead widths can be obtained by varying the laser power or travel speed according to the transfer functions so that a constant overlap ratio is maintained. This method has been used to fabricate solid compressor airfoils, which showed good dimensional accuracy and no lack-of-fusion defects. This method has also been used to solve other problems where the dimensions are hard to maintain with constant processing parameters. An example of such regions would include overhanging regions (surfaces with declining angle less than 35 degrees) and regions where the cooling rate changes substantially during fabrication.