Dimensional inspection of spur and helical gear teeth manufactured by Laser Metal Deposition

Laser Metal Deposition (LMD) allows the fabrication of complex shapes onto non-planar surfaces. This manuscript presents a 3D-scanning strategy for the dimensional inspection of LMD-manufactured gear teeth onto cylindrical substrates. The standard registration (alignment) methods are ineffective in the context of LMD because they minimize the global distance between the reference model and the 3D-scanning point cloud. This global minimization wrongfully biases the alignment. In response to this limitation, this manuscript discusses a registration procedure that avoids global distance minimization by sequentially aligning the datums (gear root cylinder and planar faces) of both datasets. This datum-alignment procedure fixes 5 out of 6 Degrees of Freedom (DOF). The final DOF is determined by finding the optimal rotation angle that minimizes the distance between the gear teeth of both datasets. The strategy is validated with actual LMD-manufactured spur and helical gear teeth onto cylindrical substrates. This strategy would also save time during the grinding process.