Tool Axis Inclination Research Articles

Influence of Tool Inclination and Effective Cutting Speed on Roughness Parameters of Machined Shaped Surfaces

Free-form surfaces in the automotive or aviation industry where the future shape of the product will contain complex surfaces raises the question of how to achieve the necessary shape of the required quality in the milling process. One of the methods of their production is the use of 5-axis milling, in which it is necessary to consider not only the input data of the process itself, but also the methodology for evaluating the desired results. Correctly answered questions can thus facilitate the choice of the inclination of the tool when machining parts of the surfaces defined in the experiment. The primary goal of the paper was to monitor the influence of tool inclination on the quality of the machined surface and effective cutting speed by evaluating surface roughness and surface topography. The experiment was designed to show the effect of different tool positions while the feed per tooth fz for the finishing operation remained constant. The best result in terms of surface quality was achieved with a tool inclination of 15° in the cutting process. The most unfavorable result was obtained with a tool axis inclination of zero degrees due to unfavorable cutting conditions.

Determination and Analysis of Working Diameters and Working Angle of the Torus Cutter Blade in Multi-axis Machining in the Aspect of Tool Wear

The aim of this study is to provide a theoretical and experimental analysis of the multi-axis milling process by the torus milling cutter of nickel-based superalloy parts in terms of surface quality and tool wear. In the analytical part, using, among other things, matrix calculus and trigonometric relationships, mathematical models were developed to describe the relationships between the tool axis orientation and the geometric parameters of the cutting layer at the contact point. On this basis, mathematical relationships for contact diameter and effective diameter were derived. The basis for these considerations is the very rarely considered working angle of the cutter blade. In part of the experimental study, machining tests were carried out for selected kinematic variants of multi-axis cutting. Based on the results obtained, it was found that as the tool axis inclination angle increases, the contact diameter increases. The effective diameter at the upper characteristic point of the cutting layer increases up to a certain angle of inclination, after which it begins to decrease. The rotational angle of the tool axis does not affect any of the diameters, but it does affect the displacement of the contact point, the values of the working angle of the tool blade and the feed-related component decrease. The result of this displacement is a change from climb milling to conventional milling, which has significantly degraded surface quality and tool life. The best results of the machining test were obtained when only the angle of inclination of the tool axis was used. It was concluded that the parameter tool blade working angle can be a control variable in a multi-axis milling process and has a major impact on the physical aspects of the cutting process.

Nonlinear error control of five-axis machining singular region

Aiming at the singular problem of large nonlinear error caused by the extreme change of rotation in five axis NC machining of complex surface. An optimization algorithm of tool path in singular region is proposed. Taking a-c double turntable five axis linkage NC machine tool as an example, firstly, the mathematical models of tool local milling ability, machining bandwidth and tool axis inclination are established. Based on the two constraint models, the mechanism of singularity and the size of singular region are analyzed, and it is proposed to adjust the side angle with the tool contact as the rotation center to avoid the singular region. The modified tool axis vector that does not meet the accuracy is interpolated recursively according to the interpolation principle. This method solves the problem of large nonlinear error caused by the extreme rotation of the rotating axis in the singular region on the basis of meeting the requirement of no curvature interference. At the same time, the processing bandwidth before and after modification is guaranteed to remain unchanged. Simulation results show that the algorithm can effectively detect the singular region and improve the machining quality in the singular region.

Increasing the Accuracy of Free-Form Surface Multiaxis Milling.

This contribution deals with the accuracy of machining during free-form surface milling using various technologies. The contribution analyzes the accuracy and surface roughness of machined experimental samples using 3-axis, 3 + 2-axis, and 5-axis milling. Experimentation is focusing on the tool axis inclination angle—it is the position of the tool axis relative to the workpiece. When comparing machining accuracy during 3-axis, 3 + 2-axis, and 5-axis milling the highest accuracy (deviation ranging from 0 to 17 μm) was achieved with 5-axis simultaneous milling (inclination angles βf = 10 to 15°, βn = 10 to 15°). This contribution is also enriched by comparing a CAD (Computer Aided Design) model with the prediction of milled surface errors in the CAM (Computer Aided Manufacturing) system. This allows us to determine the size of the deviations of the calculated surfaces before the machining process. This prediction is analyzed with real measured deviations on a shaped surface—using optical three-dimensional microscope Alicona Infinite Focus G5.

Determining the effect of tool posture on cutting force in a turn milling process using an analytical prediction model

Turn milling is a key technique that can be used to achieve high-efficiency machining and improve life of tools used for difficult-to-cut materials because intermittent cutting with multiple cutting edges can suppress a rise in temperature compared with conventional turning. However, the contact condition between the rotary tool and the cylindrical workpiece varies significantly depending on the tool posture, which is defined by the tool axis inclination angles against the workpiece: namely, lead and tilt angles. Thus, clarifying the effect of the lead and tilt angles on cutting forces in turn milling is essential for determining the optimal tool posture. In this paper, we propose a simulation model to predict the cutting force for 5-axis turn milling considering the contact behavior between the tool and workpiece depending on the tool posture. The workpiece is modeled as a point cloud and any points that interfere with the tool volume are removed when the tool edge passes the surface of the workpiece. We examined the simulated cutting forces using a radius end mill as a linear function of the uncut chip thickness and found that the predicted cutting forces were in agreement with the experimental results for several combinations of tool postures and feed rates. We also clarified that the tool posture significantly affects the maximum cutting force, which varies even if the material removal rate is maintained at a constant value in the turn milling process.

The influence of inclination of the axis of the toroidal tool on a flat surface roughness

The paper follows the experimental analysis of the influence of the tool axis inclination on the roughness on a flat surface. The tool used in this case is a toroidal cutter radius around the corner. This will process a flat surface in 4 cases. We will experiment with the processing of a flat surface with the tool axis inclined in the positive direction A, negative direction A, positive direction B and negative direction B. The term of comparison in the four cases is surface quality. The purpose paper is to determine the best option for inclination tool toroidal.

Experimental research of tool axis inclination angle influence upon surface roughness in ball-nose end milling of polyetheretherketones (Tecapeek natural)-Part I

In order to find solutions for different medical applications like implants and reconstructions in clinical dentistry, orthopaedic or spinal implants, the polyetheretherketones have achieved a remarkable application because of their properties. The polyetherketone materials combine excellent wear resistance with very good mechanical properties, even under thermal load. Because of these qualities it is used also in different applications in automotive, aerospace and food industry. For each application, no matter if the process to obtain different shape is extrusion, injection moulding or machining by turning or milling, the surface roughness value is critical. For pieces with complex surfaces some finishing operations are necessary. The ball nose end milling process is recommended in this case because of its versatility. In ball nose end milling process the influence of tool axis inclination angle has a big influence upon surface roughness value. In this way theoretical studies are required in order to establish the influence of this parameter upon effective cutting speed. Also, experimental research method was needed in order to establish the quality of surface in terms of surface roughness. The experimental research results establish the most favourable values of inclination angle for Tecapeek-natural material in comparison with C45 material.

Development of inclined planetary milling machine with automatic tool axis inclination instrument

The study deals with a novel drilling technique of carbon fiber reinforced plastic (CFRP) with high precision and efficiency. The characteristic of high specific strength of CFRP. It enables to reduce the mass of the structure, improve the fuel economy, and reduce the environmental load. Alternating structural materials to CFRP for various products are ongoing. However, due to the structure of CFRP, burrs and delamination occurs when drilling a hole. Presently, it is reported that the helical machining and the planetary drilling processes are efficient to avoid burrs and delamination. Even though, by using those methods, there are limit to improve the circularity and the surface roughness of the hole. It is due to the vibration caused by the structure of the machine.In the research, we suggest the inclined planetary milling to solve the problems. The inclined planetary milling is a drilling method with a precession movement, which is performed by rotating an inclining spindle in the rotation of the tool. The inclined planetary milling enables to reduce the vibration of the machine, miniaturize the machine, improve the quality of the hole and reduce the machining cost. In our previous research, we have fabricated a prototype machine, carried out drilling experiments and confirmed its superiority to other machining methods. In the case of the prototype, the dimension of the hole sets manually. It does not seem practical and limits the conditions of experiments. In the study, we fabricated a new prototype that enable to set in practical conditions, conduct experiment and confirm superiority toward other processing methods.

Mechanical and technological aspects of micro ball end milling with various tool inclinations

This paper is focused on the evaluation of mechanical and technological aspects of the micro ball end milling of hardened TOOLOX 44 steel. The experiment includes the measurement of acceleration of vibrations during the micro milling tests with variable feed per tooth and tool's axis inclination angle values. The next step involves the analysis of dynamics, based on the determination of measured signals’ statistical measures and Fast Fourier Transform (FFT). This stage includes also the prediction of micro ball end milling forces on the basis of mechanistic model considering run out, variable edge forces, and kinematics of low radial immersion milling with tool axis inclination. Subsequently, the optimization of the micro ball end milling process is conducted. This procedure is carried out by the minimization of process responses with the application of a method based on the minimization of total desirability function. In the last stage, the obtained optimal values of tool's axis inclination angle and feed per tooth are validated during the micro milling tests involving the measurements of machined surface roughness. Research reveals that micro ball end milling with the optimally selected tool's axis slope along the toolpath and feed per tooth affects the minimization of milling vibrations and improvement in surface finish.

A virus-evolutionary multi-objective intelligent tool path optimization methodology for 5-axis sculptured surface CNC machining

Sculptured surface machining is a material removal operation essentially adopted to manufacture complex products. Computing optimal tool paths with reference to ideally designed CAD models is indispensable to be able to suggest machining improvements in terms of high quality and productivity. The present paper proposes a new methodology based on a virus-evolutionary genetic algorithm for enhancing sculptured surface tool path planning through an automated selection of values for standard 5-axis end milling strategies' machining parameters to be decided upon in the context of a simulation-based; software-integrated, multi-objective optimization problem. The problem involves surface machining error as the first quality objective represented via the mean value of chordal deviations that tool path interpolation yields and effective radius of inclined tools that affects scallop. Machining time is the second quality objective entering the problem to assess productivity; whereas the number of cutter location points created for each tool path evaluation is also considered. Tool type, tool axis inclination angles as well as longitudinal and transversal steps are considered as the independent parameters in the case of 5-axis machining. Results obtained by conducting evaluation experiments and simulation tests accompanied by an actual machining process provided significant insight concerning the methodology's efficiency and ability of suggesting practically viable results.

工具磨耗抑制を考えた5軸仕上げ加工

It is important to reduce the tool cost in terms of the rationalization of manufacture. On the supposition of 5-axis control machining of metal molds, it is planned to suppress the tool wear by moving the cutting position of ball-end mills. Based on this concept, the experiments are conducted by changing the tool axis inclination direction and the tool swing rate. The tool axis inclination direction is determined at every 45 degrees from the tool feed direction, that is, 8 types. The tool axis inclination angle is selected to be 30 degree from the tool axis in terms of the machined surface roughness with reference to the reported research result. The tool swing rate is appointed by degree per tool feed with the center point of 30 degrees moving from 15 to 45 degrees, taking account of the interference and down-cut operation. As a result, it is confirmed that there exists the appropriate tool axis direction and the tool swing rate, which allow the suppression of tool wear and the realization of good surface roughness.

Feed-Interval Scallop Height Estimation Using Multi-axis CNC Milling Machine

This research presents a mathematical model of feed-interval scallop height, where in a machined surface there are two types of scallop height, the pick(path)-interval scallop and the feed-interval scallop. The pick-interval scallop is generated by the finite pick offset between the successive cutting paths, while the feed-interval scallop is generated by the finite increment between the successive tooth feeds. New model that describes and predicts the geometric generating mechanisms of the feed-interval scallop height have been derived using torus cutter which is commonly used in multi-axis milling machine. The machining parameters (effective tool cutter radius, feed per tooth and the magnitude of tool axis inclination angles) have been considered in theoretical and experimental work to study the effect of these parameters on this type of scallop height. From theoretical and experimental work it was found that at high-speed machining, the feed-interval scallop is more important to the surface roughness than the path-interval scallop, and the feed-interval scallop is very sensitive to the tool-axis inclination angle. The feed-interval scallop height decreased sharply and quickly within a few degrees of the tool-axis inclination to the normal workpiece surface. In general, an inclination angle equal to is good enough for all tool diameters used in the present work, namely (6,8,10 12 mm).

Progressive Strategy of Milling by means of Tool Axis Inclination Angle

Progressive Strategy of Milling by means of Tool Axis Inclination Angle

Dynamic behaviour improvement for a torus milling cutter using balance of the transversal cutting force

This article deals with five-axis machining of free-form surfaces with torus cutters and round inserts. An orientation of the tool axis to make a dynamic tool behaviour as stable as possible is presented in this work. With this new method an improvement of 50% on different roughness criteria can be obtained. For that, tool axis inclination will be towards the back of the tool compared to the feed direction that will allows to all inserts to machine simultaneously. The global cutting phenomenon is then continuous and it is thus possible to find a tool axis inclination that decreases its vibrations. It will be shown that this calculated tool axis inclination allows on the one hand to reduce the transversal tool deflections and in the other hand to stabilize the dynamic tool behaviour. A better quality on the finished workpiece is then obtained.

Optimum orientation of a torus milling cutter: Method to balance the transversal cutting force

In this paper, a new method for tool positioning in milling on torus cutters with round inserts is presented. A new criterion associated with balancing of the transversal cutting force is used to compute a tool orientation. The considered tool inclination is towards the back of the tool. In this case, all inserts work simultaneously and generate a continuous cutting phenomenon. Each of the inserts produces a transversal cutting force; some being positive while others are negative. A small tool axis inclination angle leads to balancing the transversal cutting force exerted on the tool and then reducing deflection and vibrations in milling operations. Firstly, this approach to the dynamic aspects relating to cutting forces in the milling process is significant for mould and die manufacturing since it allows polishing time to be reduced. In addition, as vibrations are reduced, enhanced surface quality can be obtained directly on free-form surfaces such as aeronautic fittings.

A study of the surface scallop generating mechanism in the ball-end milling process

This paper presents the model, simulation and experimental verification of the scallop formation on the machined surface in the ball-end milling process. In the milling process, the cutting edges of the cutter are in a motion of combined translation and rotation. The periodical variation of the cutting edge orientation during spindle rotation results in two kinds of scallops generated on the machined surface: the pick-interval scallop and the feed-interval scallop. Because of the low feed and comparably large pick used in the conventional ball-end milling process, the emphasis of previous works has been placed on studying the geometric generating mechanism of the pick-interval scallop while the feed-interval scallop has been largely ignored. Trend of the high-speed and high efficiency machining, however, has pushed the feed reaching the same level of the pick. For the high-speed machining where the high feed/pick ratio is used, the feed-interval scallop must be taken into account. This paper presents a new model that describes the path-interval and feed-interval scallops generating mechanism in the ball-end milling processes. Parameters such as the tool radius, feed/pick ratio, initial cutting edge entrance angle, and tool-axis inclination angles have been studied and experimental verified. It was found that the feed-interval scallop height was 3–4 times large than the path-interval scallop height at the high-speed machining case. The scallop height was continuously reduced by increasing the tool-axis inclination angle. An inclination angle up to 10° is, however, good enough for most tool diameters from the surface roughness viewpoint.