The uniformity of remaining volume on rough-machined sculptured surface parts

Abstract

In rough machining of parts with sculptured surfaces, two main objectives are usually considered: machining time and overall removed material at the end of the roughing phase. The outcome of that phase is critical for the subsequent finishing phase. This paper proposes a method for measuring roughed part quality through calculation of the local difference between the roughed part geometry and the ideally finished part geometry. The method calculates the height from a point lying on the roughed surface to its projection on the ideally finished part surface. Using the API of a CAD system for this purpose proves computationally inefficient. Therefore, a mean distance between a triangle of the roughed surface triangular mesh and the ideally finished part surface region lying in a suitable envelope is calculated instead. The calculation is repeated not for all triangles of the mesh, but for a sample as low as 3%, which, according to the Levene statistical test suffices, thereby, reducing computational cost by orders of magnitude. The method ultimately yields a single figure, i.e. the standard deviation of local differences between the roughed and finished part, normalized by the mean difference. The concept was tested on sculptured surface parts of various mechanical and operational properties and was proven efficient in all test cases.