Iso-scallop tool path building algorithm “based on tool performance metric” for generalized cutter and arbitrary milling zones in 3-axis CNC milling of free-form triangular meshed surfaces

Abstract

In order to generate a tool path, scallop height should be under the given precision requirement and the tool path should be as short as possible. Iso-scallop tool path generation method is traditionally used to generate the effective tool path. This paper discussed a new method to generate a iso-scallop and contour-parallel tool path for a generalized cutter and an arbitrary area on free-form surface in 3-axis CNC milling. The milling surface, originally represented as a triangular mesh, and the generalized cutter surface are converted into voxel-based depth maps. Milling zone map with the same resolution as the part depth map is used to define an arbitrary milling area. First, the points on the boundary of milling area are marked in order to build the tool path that can follow a boundary line. Second, different cutter location positions are tried in order to satisfy two conditions: milling the material from the selected boundary points within the tolerance limit and having the maximum material removal rate on the way from the previous cutter location point. The algorithm is repeated until the whole area to mill is finished. Due to the high demand of computational power, graphics processing unit is employed for the most time consuming operations.