Five-axis High-speed Machining Research Articles

Necessity of multidimensional evaluation of the high-speed ball-end milled surface of hardened AISI D2 steel from a wear resistance perspective

This paper focuses on revealing the anisotropy of surface integrity and wear resistance of high-speed ball-end milled surfaces of hardened cold work die steel AISI D2. Dry milling tests were performed on a five-axis high-speed machining center by using a two-edged coated solid carbide ball-end milling cutter. Then, wear resistance of a hard milled surface was evaluated through block-on-ring wear tests under unlubricated condition. Results showed that ball-end milled surfaces present anisotropic characteristics in terms of surface topography, subsurface microhardness, and yield strength. Moreover, the wear resistance for ball-end milled surfaces shows dependence on sliding direction because of the anisotropy of surface integrity. Benefiting from surface work hardening, wear loss for the hard milled surface was at least 62% less than that for polished ones in the initial wear stage (10 min). However, the subsurface softening zone induced by a high-speed hard milling process has poor wear resistance due to the decrease of microhardness and yield strength. This study indicates the necessity of multidimensional evaluation for high-speed ball-end milled surfaces and the possibility of improving wear behavior by selecting appropriate sliding direction.

Contour error pre-compensation for five-axis high speed machining: offline gain adjustment approach

This paper presents an offline gain adjustment (OGA) approach to reduce contour error in five-axis high speed machining. The proposed contour error formulation is based on the estimation of tool contact points and the OGA is inspired from the idea of model predictive control (MPC). The control gains used in the position loop of servo drives are optimally adjusted offline to reduce the contour error for the considered trajectory. The obtained gain profiles are computed preserving axis kinematic limitations, stability criterion of servo drives, and the motor current constraints. The OGA is developed thanks to a validated machine simulator. The simulation results prove that the OGA reduces significantly the contour error in five-axis high speed machining.

Smoothing Rotary Axes Movements for Ball-End Milling Based on the Gradient-Based Differential Evolution Method

Ball-end milling is widely used in five-axis high-speed machining. The abrupt change of tool orientations or rotary axes movements will scrap the workpiece. This research presents a smoothing method of rotary axes movements within the feasible domains of the rotary-axes space. Most existing smoothing methods of tool orientation or rotary axes movements employ the Dijkstra's shortest path algorithm. However, this algorithm requires extensive computations if the number of the cutter locations is large or the sampling resolution in the feasible regions is high. Moreover, jumps in the results obtained with the Dijkstra's shortest path algorithm may occur, because the optimization problem has to be converted from a continuous problem into a discrete problem when using this algorithm. The progressive iterative approximation (PIA) method incorporating smoothness terms is established as a gradient-based optimization method to smooth the rotary axes movements in this research. Then a gradient-based differential evolution (DE) algorithm, combining the global exploration feature of the DE algorithm and the local searching ability of the gradient-based optimization method, is developed to solve the smoothing model. The validity and effectiveness of the proposed approach are confirmed by numerical examples.

Five-axis Flank Milling Tool Path Generation with Smooth Rotary Motions

The smoothness tool path is essential in five-axis high speed machining. However, the smoothness of the tool orientation in the part coordinate system cannot assure the smooth motions of the rotary axes of a five-axis machine tool because the conversion of tool posture from the part coordinate system to the machine coordinate system is nonlinear. To generate a tool path with smooth rotary motions of the five-axis machine tool, the tool path in this paper is represented with three spline curves: the cutter location curve and the two trajectory curves of the rotary axes of the machine tool, so that the rotary axes’ motions can be simultaneously smoothed. For a flank milling tool path, the geometric deviations between the envelope surface of the tool movement and the design surface should be respected while smoothing the tool path. The point-to-surface distance is adopted to calculate the geometric deviations, and then a smoothness optimization model is developed to smooth the rotary axes’ motions using the weighted least squares method. A numerical example of five-axis flank milling of a S-shape surface is given to confirm the validity and efficiency of the proposed approach.

Modeling of tool wear for ball end milling cutter based on shape mapping

Tool wear is thus of great importance to understand and quantitatively predict tool life. In this paper, a tool wear model for ball end milling cutter is established with considering the joint effect of machining conditions for predicting tool wear. The modelling process of tool wear is given and discussed according to the specific conditions. In order to determine coefficients of the established tool wear model a new tool wear estimation method based on shape mapping is used to measure tool wear which is suitable to prepare tool wear data for the established model. So tool wear for each experiment can be obtained from the tool wear estimation method and be used to fit the proposed tool wear model by using multiple linear regression method. Experimental work and validation are performed on five-axis high speed machining centre for cemented carbide cutting tool milling stainless steel. Experimental results indicate that tool wear can be predicted within 10 % on an average using the established tool wear model and the established tool wear model is suitable to predict tool wear at certain range of cutting conditions for milling operation.

Rapid Toolpath Correction for Five-Axis High Efficiency Machining Based on Image Analysis

Five-axis high speed machining can improve the efficiency and accuracy obviously, but the machining errors and tool interference are likely to happen due to the complexity of tool motion. So the collision detection and verification of tool path are very important and necessary before machining the part. Using a combination of process simulation and collision detection based on image analysis, a rapid detection approach is developed in this research. The geometric model provides the cut geometry for the collision detection and records a dynamic geometric information for in-process workpiece. For the precise collision detection, a strategy of image analysis method is developed in order to make the approach efficient and maintian a high detection precision. An example of five-axis machining propeller is studied to demonstrate the proposed approach.

Collision-Free Tool Path Generation for Five-Axis High Speed Machining

Collision detection is a critical problem in five-axis high speed machining. Using a combination of process simulation and collision detection based on image analysis, a rapid detection approach is developed. The geometric model provides the cut geometry for the collision detection and records a dynamic geometric information for in-process workpiece. For the precise collision detection, a strategy of image analysis method is developed in order to make the approach efficient and maintian a high detection precision. An example of five-axis machining propeller is studied to demonstrate the proposed approach. It has shown that the collision detection task can be achieved with a near real-time performance.

Application of Virtual Manufacturing to Impeller Five-Axis High Speed Machining

For taking advantage of high speed machining(HSM) in complex curved surfaces as impeller, the virtual manufacturing technology is adopted before the real machining, which can eliminate tool collision interference phenomenon of the trial cutting, avoid complicated process of trial test , forecast machining results efficiently. The simulation tests were proceeded to the each impeller procedure NC program by using the VERICUT virtual manufacturing soft to modeling five-axis machine tool HSM600U, and the result compared with the real machining is identical with one other. So it is tested that applying this technology can forecast the machining process truly.

Application of Virtual Manufacturing to Impeller Five-Axis High Speed Machining

Application of Virtual Manufacturing to Impeller Five-Axis High Speed Machining

Five-axis machining time estimation algorithm based on machine characteristics

Abstract In this paper, we present a machining time estimation algorithm for five-axis high-speed machining. Estimation of machining time plays an important role in process planning and production scheduling of a shop. In contrast to the rapid evolution of machine tools and controllers, machining time calculation is still based on simple algorithms of tool path length divided by input feedrates of NC data, with some additional factors from experience. We propose an algorithm based on five-axis machine behavior in order to predict machining time more exactly. For this purpose, we first investigated the operational characteristics of five-axis machines. Then, we defined some dominant factors, including feed angle that is an independent variable for machining speed. With these factors, we have developed a machining time calculation algorithm that has a good accuracy not only in three-axis machining, but also in five-axis high-speed machining.

Five-Axis High Speed Machining of Sculptured Surfaces by Surface-Based NURBS Path Interpolation

AbstractThis paper presents a new surface-based NURBS path interpolation for 5-axis high speed machining (HSM) of sculptured surfaces. Detailed formulation of the new time-parameter NURBS path interpolation is proposed to convert the NURBS part surface into time-variable parameterized tool paths for 5-axis sculptured surface machining. Based on the machine configurations, the surfacebased NURBS path interpolation directly derives the pivot point location and the spindle orientation to control the machine motion. With the proposed new method, the traditional chordal and linearization deviation errors in 5-axis NC machining can be reduced. Computer implementations and illustrative examples are also presented in this paper. The presented techniques can be used in the CAD/CAM systems and the NC controllers for 5-axis high speed machining of sculptured surfaces.

Compensation of systematic errors in five-axis high-speed machining

A method is described for the compensation of errors associated with tool path generation, particularly during five-axis high-speed machining (HSM). Information on machine tool performance and its dynamic features is used to calculate possible errors and convenient modifications of the NC program, thereby avoiding errors when parts are actually being machined. This 'preprocess method' by means of postprocessing with NC software is presented. The errors dealt with are mainly servo lag errors, but the explored approach can support most systematic errors associated with machine tool performance. These are briefly summarized. Research so far has largely been aimed at the implementation of compensation routines in the CNC controller and at corrections in real time. The problem is that most applications are only available for three-axis milling. The presented approach (compensation before machining by using software routines in a specially designed postprocessor) is based on a fuzzy logic expert system. The benefits can be summarized as data reduction, data improvement, precontrol of feed, and improved component accuracy. The applied procedure is also convenient for implementation in an industrial environment by retrofitting existing equipment. The suggested method provides improved control over machine dynamics, permitting high-speed machining centres to maintain a maximum or near-maximum feed rate despite axis reversals and tool path changes, even at corners. Two categories of results are presented, namely the management of NC data related to expected performance of the machine tool and improvements of the machine tool performance in terms of productivity and accuracy of the machined test components.