In an Additive Manufacturing (AM) process, the layer-by-layer fabrication of a part leads to a staircase effect affecting its final quality. Parts manufactured using AM process may not satisfy the specified tolerance requirements due to this staircase effect. An improved surface quality (reduction in staircase effect) and a reduced build time are the two most important driving factors which led to the development of different slicing algorithms. The uniform slicing approach presents a tradeoff between the part’s quality and the build time whereas current adaptive slicing methods are computationally expensive.
An innovative algorithm to compute adaptive slice thicknesses in an AM process is presented in this study. This method, termed as Modified Boundary Octree Data Structure (MBODS), is used to convert the STL file of an object to an octree data structure, by considering the part’s geometry, the AM machine parameters, and user defined tolerance values. This algorithm ensures that the fabricated part satisfies the required geometric tolerances. The developed algorithm is characterized by its simple structure and its modest storage space and computation time requirements.
A subsequent algorithm computes the variable slice thicknesses using the MBODS representation of the part and virtually manufactures the part using these calculated slice thicknesses. Points sampled from the VM of the part are inspected to evaluate the part errors. In the present study, the volumetric, profile and cylindricity errors have been evaluated using the adaptive slice thicknesses. The MBODS algorithm is validated by comparing it with uniform slicing approaches using various constant slice thicknesses. The developed algorithm is observed to be more effective in improving the part-quality with lesser number of slices.