High-speed Machining Center Research Articles

Key Technology of 5-Axis NC Programming and High-Speed Milling for Integral Impellers Based on the General Software UG

Integral impellers are very important parts in the fields of aerospace, shipping and locomotive, whose manufacturing accuracy directly affects performance of key equipments. In developed countries special NC programming software is widely used in order to manufacture integral impellers, the vast majority of enterprises have not special NC programming software of integral impellers owing to expensive cost in China. Key technology of 5-axis NC Programming for integral impellers was solved by using the general software UG and precision machining of integral impellers had been implemented in 5-axis high-speed machining centre.

Cost estimation support tool for vertical high speed machines based on product characteristics and productivity requirements

This work concerns a machine tool selection problem, which consists of selecting the most suitable machine to satisfy manufacturing company requirements. The main goal of this work is to develop a cost estimation support tool for vertical high speed machining centres based on final part and productivity requirements of the company linked with machine tool characteristics available in the catalogues in order to apply the cost model and to calculate machine tool cost estimations. The cost model presented is based on multiple regression analyses and provides reasonably accurate market cost predictions. Applying the proposed cost model will help the user to determine the approximate market cost of the machine and can be especially interesting for decision makers in the preliminary stages of a selection process because it avoids long and costly studies.

Finite Element Analysis and Structure Optimization of Machine Tool Worktable

DVG850 high-speed machining center worktable is taken as research object, in order to meet the overall performance requirements of the high-speed machining center, 3D model of worktable is established in SolidWorks. Static analysis and modal analysis are carried out in ANSYS Workbench, and then the worktable is optimized in topology optimization module of ANSYS Workbench. According with the analysis results, the worktable structure has improved. The improved worktable keeps the original’s static performance, and enhances the dynamic performance; however, its quality is lighter than original structure by 23.2 kg.

Research on Virtual Design System for Spindle of High-Speed Machining Center

Aiming at the question of high-speed spindle’s long development cycle, take the structural design and the performance analysis of cnc machining center’s high-speed spindle system as key points, use the cad technology, fea technology,dynamic simulation technology and virtual design theory, and integrate them into an integration technology, the virtual design and analysis software system devoted to the cnc machining center’s high-speed spindle was developed too, and gave parts of the operating instance. Through the practical application in one large-scale enterprise of machine tool, the fea sibility and practicability of proposed system principle and implementation techniques were verified, and the better design quality and higher efficiency were shown too.

Sensitivity Analysis of DVG850 High-Speed Vertical Machining Center Headstock

The headstock is one of the most important parts of a machining center, however there are a lot of designing variables that may influence the static and dynamic capability of the headstock. How to find these variables and optimize them seems to be very important. In this paper, using the modal frequency as the performance index, Pro/Mechanical was used to analyse the sensitivity of the DVG850 high-speed vertical machining center headstock. The result of the analysis was a set of main design-variables that influence the first-order natural frequency of the headstock. The machine’s typical operating conditions were compared against the results of the sensitivity analysis. This provided a basis for structural design and optimization of the headstock directly and quickly.

Machining Center Worktable Static Stiffness Spectrum Drawing and Analysis

The main work is calculating and analyzing the worktable’s static stiffness in different positions, and drawing 3D static stiffness spectrum of the worktable in Z direction according to the analyzing results. DVG850 High-speed machining centre is taken as the research object, to establish the solid modal in ANSYS Workbench and analyze the worktable’s static stiffness in different positions. and the paper uses its worktable as the researching object. According to the results the spectrum of the static stiffness of the worktable is drawing in Matlab. The spectrum shows that the more the position is near the edge, the larger the static stiffness is, and it changes faster, however the middle is smaller. This spectrum has certain directive significance for the optimal design and improvement of product quality of design.

Development of process monitoring system in drilling process using fuzzy rules

This study describes the development of process monitoring system in drilling process in high speed machining center. The system monitors the several state variables of the cutting process of a drill. However, the thrust force and torque signals have been chosen to detect and monitor the drilling process, the acoustic emission signal has been also analyzed. Experimental data have allowed defining statistical behavior of the variables for non-fault conditions, tool wear and breakage. The new approach in this project is to use the standard data acquisition software LabVIEW for the purpose of data collection, signal analysis, decision making and sending back the message to the machine.

The Process Strategies of Mould High-Speed Machining and their Applications in the Environment of PowerMILL

High-speed machining requires the support of high intelligent CAM software as well as customized machining strategies and properly selected machining parameters. Only by combining the two can the advantage of high-speed machining be made full use of. Compared to ordinary NC cutting, high-speed machining has special requirements for process strategies, CAM system and tool path. A complete tool path includes approaching/retracting tool, moving tool and tool path. Based on the above principles, a mould part is successfully processed using the PowerMILL software at the high-speed machining centre of DMG-DMU40T. The maximum hardness of the mould part is HRC50. There’s a 30 degree corner in the cavity with a transition radius of 3mm. The whole process can be divided into three stages: rough, semi-finish and finish machining and each stage involves the selection of tool path, the selection of tool, the selection of cutting parameters (including spindle speed, feed speed and depth of cut), and the application of PowerMILL specific machining methods (such as Race-line machining, rest roughing, automatic trochoidal machining, 3D offset finishing and etc).

Model-reference feedforward controller design for high-accuracy contouring control of machine tool axes

This paper addresses the design of a feedforward controller that enables machine tool axes to have the desired dynamics. The controller adopts a simple configuration of a reference model and compensators for feedback and mechanical dynamics. It improves the dynamic response of conventional cascaded control based on performance requirement. The designed feedforward controller is implemented for the contouring control of a high-speed and high-accuracy machining center. It is shown that the contouring accuracy in submicron-level has been achieved by using the designed controller.

Research on NC Technology for High Speed Milling

In the manufacturing industry, high speed milling plays a very important role. The paper introduced a number of essential core component of the key technologies in high speed machining center such as powerful computer numerical control systems, motion control card, post –processing method, processed trajectory control technology (Look Ahead) and high speed processing of programming. The speed control, post processing and look-ahead control are focused on considering, and the corresponding improved methods are brought forward.

Functional check test for high-speed milling centres of up to five axes

This paper offers a system for checking three or five axes high-speed machining centres by milling a sample sphere pattern. Using the right choice of toolpath, it is possible to check and compare the performance which the centre is capable of following. The main features under study here are ease of use and the great amount of information that can be drawn regarding high-speed machine performances, including the geometrical precision of the machine and tool setup for the chosen machining conditions.

Cutting Force and Tool Deflection Predictions for High Speed Machining of Hard to Cut Material

The dimension accuracy and the too life are the major issues of the machining of hard-to-cut materials. To fulfill the requirements of accuracy and tool life needs not only well planning of cutting path but also the proper cutting conditions of cutters. The vibration and deflection of cutters caused by poor selection of cutting conditions can be predicted using models of cutting force and tool deflection. In this paper, a cutting force model considering the effect of tool helical angle and a cantilever beam model of tool deflection were proposed for the high speed machining of hard-to-cut material SKD11. The shearing force, the plowing forces, and the helical angle of cutters are considered in the elemental force model. The material of workpiece, SKD11, studied in this paper is commonly used for the die and mold industries. The cutting constants of the proposed force model are determined via the cutting experiments carried out on a high speed machining center. A dynamometer and a high frequency data acquisition system were used to measure the x-, y-, and z-direction cutting forces. The obtained cutting constants were used to predict the cutting forces and compared with the results obtained from the cutting experiment of verification using cutters with different helical angles. The theoretical and the experimental cutting forces in the x-, y-, and z- direction are in good agreement using flat cutters with 30 and 45 degrees of helical angle. The dimension deviations of the cut surface in the cutting experiment case of tool deflection were measured using a touch probe and an infrared receiver installed on the machining center. The measured average dimension deviation, 0.163mm, is close to the predicted tool deflection, 0.153mm, using the proposed cantilever beam model. The comparisons of the cutting forces and the average of the cut surface dimension deviation are in good agreement and verify the proposed cutting force and the tool deflection models are feasible and useful.

Stability analysis in milling of thin-walled workpieces with emphasis on the structural effect

Regenerative chatter easily occurs in milling and has become the common limitation to achieve good surface quality and high productivity. For the purpose of chatter avoidance, the structural effect of the thin-walled part should be considered for the milling chatter stability analysis for the optimization of axial cutting depth and spindle speed pairs. The main objective of this paper is to examine the link between the structural modes (i.e. modal shapes) and the chatter stability limits in the case of finish milling thin-walled workpieces. In this paper, the dynamic stability of the milling process of thin-walled workpieces is investigated through a two-degree-of-freedom mechanical model. The mathematical relationship between the critical axial depth and the thin-walled part modal shapes is deduced and an optimal calculation process of milling stability lobes is presented. Peripheral milling of aluminium alloy (2A70 Al) plates is carried out on a computer numerically controlled (CNC) five-axis super high-speed machining centre to validate the method. The experimental results agree with the prediction by the presented method. Additionally, the experimental results show that the cutting stability is also influenced by the modal frequencies of the thin-walled part, which have a great influence on the milling stability analysis when the tool passing frequency (i.e. the inverse of the tooth passing period) harmonics are close to the modal frequencies of the part. The presented method is effective in the prediction of milling chatter limits in the thin-walled case for the optimization of machining parameters.

Design and static performance of high speed machining centre with “direct drive”

“Direct drive” is an ideal method for speeding machine tools. In the structure of a CNC machining centre with “direct drive”, the linear motor’s primary and secondary parts are assembled into the worktable and machine bed respectively to directly drive the worktable. The built-in rotary motor is assembled in the spindle to realize the main transmission system of the machine tool “direct drive”. All mechanical transmission elements in machine tools are eliminated. High speed, efficiency, and accuracy are easily obtained. However, in this type of “direct drive” machining centre, the magnetic attraction force between the primary and the secondary linear motors and the dynamic impact at acceleration and deceleration are directly imposed on the machine tool, and influence the performance of the machining centre. This paper analyzes the special demands of “direct drive” on the machine centre, and introduces a new structure of the machining tool. The worktable and machine bed are optimized to meet the special demands of “direct drive”. Static performance simulation on the machining centre is done to reveal an ideal result.

Tool life of nanocomposite Ti–Al–Si–N coated end-mill by hybrid coating system in high speed machining of hardened AISI D2 steel

Abstract Ti–Al–Si–N films were deposited on WC–Co substrates by a hybrid coating system. The synthesized Ti–Al–Si–N films were revealed to be composites of solid-solution (Ti,Al,Si)N crystallites and amorphous Si 3 N 4 by instrumental analyses such as XRD and HRTEM. The highest micro-hardness value (50 GPa) was obtained from the Ti–Al–Si–N film having the Si content of 9 at.%, the microstructure of which was characterized by a nanocomposite of nc-(Ti,Al,Si)N/a-Si 3 N 4 . The tool lives of Ti–Al–Si–N coated tool for AISI D2 steel of hardness 62 HRC were studied under various cutting speeds in high speed machining center. Tool wear curves with cutting length were presented.

Efficiency Comparison of Cutting Strategies for End Milling Processes Under Feedrate Scheduling

Technical advances in high-speed machining centers and cutting tools have made high-speed cutting a major player in manufacturing applications, but high-speed cutting provides higher machining efficiency only when machining conditions are appropriately set. In contrast, expert job shop operators often choose a heavy cutting strategy subject to higher depth of cut and a lower feedrate. Feedrate scheduling schemes are widely recognized as practically feasible for optimizing machining conditions in high-speed cutting. We compared the productivity of high-speed milling and heavy milling, assuming that using feedrate scheduling optimizes machining conditions. Possible cutting strategies are interpreted as constraints on cutting conditions or cutting performance, then machining conditions are scheduled optimally to maximize the productivity. A case study illustrates these points.

Effect of the minimum quantity lubrication in high-speed end-milling of AISI D2 cold-worked die steel (62 HRC) by coated carbide tools

The objective of this paper is to compare the tool performance of Ti0.75Al0.25N and Ti0.69Al0.23Si0.08N coated carbides end-mills deposited by hybrid coating method, using flood coolant(wet), dry and minimum quantity lubrication (MQL) conditions in the high-speed machining of AISI D2 cold-worked die steel (62 HRC). Superhard Ti–Al–Si–N films, characterized as a nanocomposite nano-sized (Ti,Al,Si)N crystallites embedded in amorphous Si3N4 matrix, was successfully synthesized on WC–Co substrates by a hybrid coating system of arc ion plating(AIP) and sputtering method. The hardness of Ti–Al–Si–N film increased with incorporation of Si, and had the maximum value ~48 GPa at the Si content of 8 at.%, respectively. The values of tool wear for coated tools were evaluated under a high-speed cutting condition using vertical high-speed machining center (Makino, V-55). It is found that cutting under flood coolant condition results in the shortest tool life due to severe thermal cracks while the use of MQL leads to the best performance. MQL is beneficial to tool life both in the Ti0.75Al0.25N and Ti0.69Al0.23Si0.08N coating tools. This conclusion proves the feasibility in the high-speed machining of high–hardened materials for industrial applications.

Estimating the cost of vertical high-speed machining centres, a comparison between multiple regression analysis and the neural networks approach

This paper focuses on the machine-tool selection problem, which consists of choosing the most suitable machine to satisfy the needs of a manufacturing company. The final decision affects the performance of the production system. Selecting an inadequate machine can negatively affect the company's results. For this reason, this is an important process that may imply some difficulties for the decision-maker. The objective of this work was to develop a cost model for vertical high-speed machining (HSM) centres based on machine characteristics. It is important to determine the cost of the machine tool, which is based on the tool's characteristics and needs to satisfy both the buyer and the manufacturer. In order to determine the main machine specifications associated with machine cost, a preliminary analysis was conducted with entry-level vertical HSM centres. As a result, two models were developed: one from the buyer's point of view and the other from the manufacturer's point of view. The cost estimation models were developed using two different techniques: multiple regression analysis (MRA) and artificial neural networks (ANN). The paper then examines the performance of the models, and compares the models’ outputs to determine which model offers the best results. Cost estimation is important to determine the machine costs that adapt best to the characteristics of manufacturing factories. The correlation obtained by the multilayer ANN models is better than the one obtained by MRA. Applying the proposed cost models will help the user (engineers or machine manufacturers) to determine the approximate machine cost based on its characteristics when they select a vertical HSM centre.

Five-axis, high-speed machining centre

Five-axis, high-speed machining centre

The effect of machinability on thermal fields in orthogonal cutting of AISI 4140 steel

The micro-scale temperature fields in the cutting of two AISI 4140 steels with different machinability ratings were measured. A custom infrared microscope was constructed; each pixel was calibrated separately to reduce measurement uncertainty. Orthogonal cutting experiments were performed on a high speed machining center with surface speeds up to 500 m min −1 and uncut chip thicknesses ranging from 0.1 mm to 0.3 mm. The results indicate that in certain critical regions of the thermal field, improved machinability correlates with significant reductions in temperature that exceed measurement uncertainties. Such micro-scale temperature measurements will help to design materials with further improved machinability.