Selection of master cutter paths in sculptured surface machining by employing curvature principle

In the Isoscallop strategy of sculptured surface machining, one of the surface edges is generally chosen as the Master Cutter Path (MCP)—from which other cutter paths are derived such that the roughness produced is uniform. In this paper, the MCPs have been chosen from the maximum or minimum curvature loci of the surface. Those loci that divide the surface into distinct zones of similar curvature are adopted as MCPs. Secondary cutter path generation is carried out employing standard isoscallop formulation and problems associated with multiple MCPs have been identified and addressed. MCPs along the locus of maximum convex curvature lead to a considerable reduction in machining time while those for minimum curvature (maximum flatness) yield a reduction in CL data file size.     

Surface topography in ball-end milling processes as a function of feed per tooth and radial depth of cut

A numerical model was developed that predicts topography and surface roughness in ball-end milling processes, based on geometric tool-workpiece intersection. It allows determining surface topography as a function of feed per tooth and revolution, radial depth of cut, axial depth of cut, number of teeth, tool teeth radii, helix angle, eccentricity and phase angle between teeth. It determines profile roughness parameters, as well as areal roughness parameters such as average roughness Sa, maximum peak-to-valley roughness St, volume of summit material V and a proposed new time coefficient Ct. It relates surface roughness to milling time. Moreover, feed per tooth and revolution f and radial depth of cut Rd were calculated that minimise parameters Sa·Ct, St·Ct and V·Ct. Minimum Sa·Ct and St·Ct provide minimum roughness with minimum milling time. Minimum V·Ct means minimum milling time with minimum material removal in manual polishing operation. At low radial depth of cut, roughness is low regardless of feed employed. On the contrary, at high radial depth of cut, roughness depends remarkably on feed: the higher the feed, the higher the roughness. In order to simultaneously minimise roughness and time, high f and low Rd should be used. In that case also volume of summit material is minimised.     

Real-time generation and control of cutter path for 5-axis CNC machining

This paper presents a new approach to real-time generation and control of the cutter path for 5-axis machining applications. The cutter path generation method comprises real-time algorithms for cutter-contact path interpolation, cutter offsetting, and coordinate conversion. In addition, a global feedback loop is closed by the CNC interpolator so as to augment the controlled accuracy in practical cutter path generation. An error compensation algorithm and a feedrate adaptation algorithm for the control loop are developed, respectively.