Optimal tool orientation in five-axis surface machining using flat-end mills

Sculptured surfaces are widely used in the design of functional components in automobile, aerospace, and die-making industries. Five-axis machining is often employed in the machining of parts with complex sculptured surfaces for improved accuracy and productivity. Owing to the two added rotational motions, five-axis machining offers higher material removal rate, better accessibility to the machined part surface, and higher surface quality over three-axis machining. However, the two rotational motions introduce critical challenges in tool gouging avoidance and optimal tool orientation determination in five-axis machining.;The optimization of the tool orientation and feed direction at a CC point highly relies on optimization parameters and involves exhaustive numerical evaluation of machining strip width at numerous feasible tool orientations and along many feed directions. In order to avoid this process, a fast and novel method is developed to determine a near optimal feed direction and tool orientation at a CC point on sculptured surfaces. To accomplish this goal, the optimal feed direction and analytical solutions for the optimal tool orientation for five-axis flat-end milling of spherical, cylindrical and toroidal surfaces are identified. A toroidal surface inscription method is developed to represent the surface geometry around a CC point on a sculptured surface by an inscribing toroidal surface Analytical solutions of toroidal surface machining are then incorporated to position a flat-end mill at a CC point on a sculptured surface along the best toroidal surface inscribing direction. Results for different case studies reveal the developed method can quickly determine a feed direction and tool tilt angle that avoid tool gouging and produce large machining strip width at different CC points on sculptured surfaces.;Machining strip width is a well-defined mathematical term, however, its maximization cannot physically maximize machining efficiency. Two new criteria of Infinitesimal Machining Volume (IMV) and Infinitesimal Machining Area (IMA) are introduced to assess the tool positioning quality at a CC point. In order to maximize machining removal volume at a CC point, the optimal tool orientation is determined using IMV criterion. IMA criterion targets optimal tool orientations at CC points that minimize the overall tool path length. It is shown through different case studies the developed criteria and methods can determine optimal tool orientations that increase machining efficiency.;Keywords: Five-axis Machining of Sculptured Surfaces; Optimal Tool Orientation; Optimal Feed Direction; Toroidal Surface Machining; Machining Strip Width; Infinitesimal Machining Volume; Infinitesimal Machining Area.;The present study examines the determination of the optimal tool orientation, which avoids tool gouging and increases machining efficiency, in five-axis flat-end milling. The influence of the tool orientation on the cut geometry in five-axis machining is studied and the effect of different parameters on machining strip width, which is a common criterion to measure the tool positioning quality, is investigated. An optimization problem is formulated to determine the optimal tool orientation that maximizes the machining strip width over feasible gouge-free tool orientations for a constant feed direction. By solving the optimization problem and analyzing the geometry of the machining strip width, it is shown that identifying the optimal tool tilt angle, instead of following the common practice of setting the tool tilt angle as zero, can significantly increase the machining strip width. In order to include the effect of feed direction on machining strip width, the optimization is extended to find the optimal feed direction that maximizes the machining strip width at a given cutter contact (CC) point.