Spatial Mapping and Stabilisation of Effective Local Feed in Diamond Turning of Curved Axisymmetric Surfaces

Diamond turning is a key ultra-precision machining process for the fabrication of high-value optical and functional components with stringent surface integrity requirements. During diamond turning of curved axisymmetric surfaces, a constant programmed feed per revolution does not result in uniform cutting conditions due to spatial variations in surface inclination. As a consequence, the local Effective feed governing tool engagement and uncut chip thickness varies across the surface, leading to non-uniform material removal and surface morphology. This paper proposes a physics-based feed compensation strategy that explicitly enforces a constant Effective local feed during diamond turning of curved surfaces. The local surface slope is used to derive a spatially varying programmed feed that stabilises tool–workpiece engagement along the spiral toolpath. The approach is applicable to spherical, aspherical, and radially modulated axisymmetric surfaces. Tool nose radius compensation, spiral toolpath generation, and feed-compensated CNC code generation are formulated within a unified framework. Surface morphology is evaluated using a geometric tool-envelope simulation. The results demonstrate that maintaining a constant local Effective feed suppresses curvature-induced variations in residual height and yields a spatially uniform surface envelope, highlighting the effectiveness of the proposed strategy for consistent surface generation in ultra-precision diamond turning.