Robust generation of the delta volume for the damaged area of a part using the marching cubes algorithm to support additive manufacturing–based part maintenance

A major advantage of additive manufacturing (AM) technology is that a product can be manufactured based on digital models that are generated using a computer-aided design (CAD) system. As a result, AM can be used for both product manufacturing and maintenance. For the maintenance of partially damaged parts using AM, the calculation of the delta volume for the damaged area is required to generate the tool paths for 3D printers. A common approach to obtaining the delta volume is to laser scan the damaged part to obtain a point cloud, which is then regenerated as a mesh model, followed by the use of a Boolean operation with the mesh model for the original undamaged part. However, a major problem with the use of point clouds for damaged parts obtained using laser scanning is that an accurate mesh model is often difficult to obtain due to noise (or outliers) and the deviation of points because of the limitations of the scanner in terms of precision. To solve this problem, the present study suggests extracting a point cloud that corresponds only to the damaged area rather than a point cloud of the entire part. By utilizing the marching cubes algorithm, a method for the robust generation of the delta volume for the damaged area is then proposed. After developing a prototype system to verify the proposed method, delta volume generation experiments are conducted on partially damaged ball valves.