Spindle Rotational Speed Research Articles

Pengaruh Putaran Spindel dan Cairan Pendingin terhadap Kekasaran Permukaan Baja AISI 4140 pada Proses Pembubutan

The purpose of this paper discusses how the effect of different spindle spin speeds on surface roughness, how the effect of different coolant fluid on surface roughness and is there an interaction between rotation speed of spindle and coolant to surface roughness in conventional lathe process. In this study the variable varied is the spin speed of the spindle that is is 630 rpm, 920 rpm, and 1250 rpm and the variation of coolant used is coolant, used cooking oil, and used SAE 40 oil. Then the surface roughness test was done. From the results of surface roughness test previously done the lathe process with variations of rotation speed of spindle and coolant, it can be concluded that: the highest surface roughness value was obtained during the turning process using used cooking oil coolant and spindle rotation used at 920 rpm. While the lowest value of surface roughness of the workpiece is obtained when using used SAE 40 oil coolant using a spindle rotation of 1250 rpm.

Thermal error compensation model for a motorized spindle with shaft core cooling based on exponential function

Thermal issues become more serious for high-speed and high-precision motorized spindle. Thermal error compensation is cost-effective and convenient to implement for this problem. To further improve the machining accuracy of the motorized spindle with shaft core cooling, this study aims to develop simple thermal error compensation model based on only the rotational speed of spindle and without any temperature data to predict the thermal error. In this study, a special measurement system was established to measure the axial thermal deformation of a motorized spindle with shaft core cooling at various speeds. A thermal error compensation model based on the exponential function was established using the experimental data. This model needs only two parameters—operating rotational speed and duration—of the motorized spindle to predict the thermal deformation and then can be easily and quickly executed without adding any extra hardware. The model is verified by comparing with experimental data at constant speeds of 4200 rpm and 7000 rpm as well as the stepped speed. The results show that the model has higher accuracy and better robustness. Under experimental conditions, when the motorized spindle operates at constant rotational speed, its accuracy increases by about 90% after compensation; when the motorized spindle operates at stepped rotational speed, the maximum thermal deformation of the motorized spindle is 29.95 μm before compensation and 2.01 μm after compensation, the accuracy of which increases by 93.2%.

Simulation thermal model of CNC machine tool operating with variable modes

The article presents the approach and the thermal modeling technique of CNC machine tools, implemented at the stage of operation. In the work, as a practical implementation of the fast modeling technology, a simulation method based on the Matlab Simulink application was used. In the work to build a thermal model of the machine tool, we used analytical solutions of the heat conduction equation. This method is applied to the machine tool operating in conditions of variable thermal processes due to varying cutting speeds. The conditions for the coordination of the thermal characteristics of the machine tool at their boundaries, corresponding to the changing spindle rotation speeds, determine the peculiarity of their construction. A feature of the implementation of the mathematical model is the use of experimental modal analysis. In this case, the modal parameters of the approximating functions are determined by solving the optimization problem. To coordinate the adjacent thermal characteristics at their borders, a special condition was adopted. Regardless of the number of temperature modes used in the model, the initial level of the first temperature mode for the next mode of operation of the machine tool was taken to be equal to the achieved level of the thermal characteristic of the machine tool at the last time interval of the current mode of operation.

An improved cutting power-based model for evaluating total energy consumption in general end milling process

Modern manufacturing enterprises are consuming a considerable amount of energy every year. Improving energy efficiency will not only benefit the enterprises economically, but also help the world to overcome various problems such as energy crisis and air pollution. To achieve this, an accurate energy consumption model is essential. The main objective of this paper is to develop an improved cutting power-based energy consumption model for general end milling process. The proposed model consists of an idle part due to auxiliary components and spindle rotation, and an additional part due to cutting workpiece materials. The first part is modelled as a function of spindle rotation speed, and the other part is considered proportional to the cutting power. Experiments under various milling conditions have demonstrated the effectiveness and efficacy of the proposed model. Comparative studies show that the proposed model is more accurate than other models. Although calibrated from slotting experiments when cutting aluminium alloy, the proposed model is applicable for general milling process. Partial-immersion milling experiments show that the prediction error of the proposed model is as low as 1.74%. When workpiece material changes to titanium alloy, its performance remains decent, with low prediction error of 2.81%. This reveals its capability to provide reliable estimation for different workpiece materials. As such, it could help avoid tedious model calibration, thus saving time, material, and energy. Finally, the energy efficiency of general end milling process is investigated through numerical experiments with the proposed model. By revealing the relationship between energy consumption and various cutting parameters, the proposed model could serve as an excellent platform towards energy-efficient manufacturing/cleaner production.

Optimisation of cutting parameters for improving energy efficiency in machining process

Abstract Reducing the machining energy consumption (MEC) of machine tools for turning operations is significant to promote sustainable manufacturing. It has been approved that selecting optimal cutting (turning) parameters is an effective approach to reduce the cutting energy consumption (CEC) within the MEC. However, the potentiality for this approach to reduce the non-cutting energy consumption (NCEC) has not received sufficient attentions. Especially, the energy consumed for spindle rotation change (SRCE) was neglected. Thus, this article aims at developing an integrated MEC model with NCEC and SRCE considered. Then, Simulated Annealing (SA) is employed to find the optimal spindle rotation speed (SRS) and feed rate which result in the minimum MEC. A case study is conducted, where five parts with different cutting lengths are processed on a lathe. The experiment results show that SA can obtain the global optimum in a short computation time when the step sizes for SRS and feed rate are 0.1 and 0.001, respectively. The optimal solution achieves a 19.28% MEC reduction. Finally, the relation between the part length and the optimal SRS is analysed, and the consequence of MEC minimisation on machining time is discussed.

Investigation of a novel finishing tool in magnetic field assisted finishing for titanium alloy Ti-6Al-4V

Titanium alloys have numerous applications in field of medical industries, aerospace and biology owing to its excellent mechanical properties and corrosion resistance. A novel magnetic field-assisted finishing (MFAF) tool is developed to carry out the finishing operation of Ti-6Al-4 V workpieces. Accordingly, the use of the designed magnetic field generator integrated with four permanent magnets as a tool to achieve alternating magnetic regions. The size of magnetic pole is calculated via theoretical analysis. Two kinds of distribution of four magnetic poles (N-N-S-S and N-S-N-S) are performed by using simulation models, and experimental measurements are conducted to validate the simulation results which show good agreement between them. Experiments were carried out to verify the performance of the designed tool for Ti-6Al-4 V workpieces finishing based on an established platform. The results show that, with the assistance of the finishing parameters control, the surface quality is dominated by varying the particle sizes, working gaps, feed rates and spindle rotational speeds. The surface roughness of 46 nm was achieved after finishing process based on the initial value of 1.121 μm, which improved by over 95%. The scratches on the surface are significantly reduced by metalloscope and field-emission scanning electron microscopy (FE-SEM) observations.

Effect of cutting parameter on tool wear of HSS tool in drilling of Kevlar composite panel

The paper reports the tool wear in the drilling of composite panel in various cutting conditions. The drilling process was applied to 4mm thickness Kevlar composite panel by using HSS drill tool (2 flutes, 12 mm diameter, 17 mm length and 118° drill point angle). The process was conducted by using a vertical machining center. The tool wear was measured by using an optical microscope with the max precision 0.01 µm. The drilling process was conducted with a constant feed rate (75 mm/min) and three levels of spindle rotation speeds (1000, 3000 and 5000 rpm). Each cutting condition was applied to two different drill tools. In order to investigate the wear rate, the tool wear was measured in several levels of cutting time (i.e., after drilling of 5, 10, 20 and 30 drill holes). The result of the experiment shows that the cutting speed gives significant effect to the tool wear of HSS drill tool when drilling Kevlar composite panel. Higher cutting speed produced higher tool wear at any cutting time level. The result of the experiment also shows the effect of continuous / discontinuous cutting. Higher tool wear was found in a direct 20 holes drilling, compare to paused drilling (i.e., start with 10 holes, pause for 20 minutes then continue with other 10 holes).

Process Parameters Decision to Optimization of Cold Rolling-Beating Forming Process through Experiment and Modelling

The cold roll-beating forming (CRBF) process is a particular cold plastic bulk forming technology for metals that is adequate for shaping the external teeth of important parts. The process parameters of the CRBF process were studied in this work to improve the process performance. Of the CRBF process characteristics, the forming forces, tooth profile angle, surface roughness, and forming efficiency were selected as the target indices to describe the process performance. Single tooth experimental tests of ASTM 1045 steel were conducted with different roll-beating modes, spindle rotation speeds, and feed speeds. Using analysis of variance (ANOVA) and regression analysis, the influence of the process parameters in each index was investigated, and regression models of each index were established. Then, the linear weighted sum method and compound entropy weight method were used to determine the process parameters for multi-objective optimization. The results show that the impact capacity and optimum value range of the process parameters vary in different indices, and that, to achieve the comprehensive optimum effect of a small forming force, high product quality, and high forming efficiency, the optimal process parameter combination is the up-beating mode, a spindle rotation speed of 801 r/min, and a feed speed of 960 mm/min.

Коррекция частоты вращения шпинделя при фрезеровании по данным численного моделирования системы: приспособление-инструмент-заготовка

Abstraсt: Machining operations are unavoidably accompanied with oscillations, which, in case of their coincidence with the natural oscillations of one of the elements of the system, can cause a resonance. The latter results in the premature failure of expensive equipment, tools and tool attachment, reduces the quality characteristics of the finished product as well as leads to rejects. Therefore, the question is raised on controlling the natural oscillation frequencies of the elements of the machine-tool system, a tool and a workpiece. Based on the finite element model of the machine-tool-device-tool-workpiece system oscillations the recommendations for choosing non-resonant rotational speeds of the milling machine spindle have been developed. The studies employed experimental, analytical, and finite element modeling methods with the use of Femap automated engineering calculation system. The experiments were carried out using Polytec measuring equipment, National Instruments LabVIEW software package, Sound and Vibration module. We have obtained the finite-element models of the device-tool-workpiece system oscillations, on the basis of which recommendations are given on setting the permissible spindle rotational speeds. The approach can find application in adjusting cutting modes when milling box-type workpieces or panel-type parts, whose workpiece geometric shape and weight differ significantly from the finished part ones.

Critical thrust force and critical feed rate in drilling flax fibre composites: A comparative study of various thrust force models

Past experimental and analytical studies for determination of critical thrust force that contributed toward minimal delamination damage in drilling synthetic fibre reinforced composites have failed to consider the recently developed natural fibre composites. From this point of view, critical thrust force and feed rate in drilling of flax fibre composites were comprehensively investigated. Three different thrust force models that were based on linear elastic fracture mechanics and properties of the composites; namely, Mode I interlaminar fracture toughness, Young modulus and Poisson ratio, were applied in order to determine the critical thrust force values. Empirical relationships between various feed rates and spindle rotational speeds with the drilling thrust force were established via regression analyses. These relationships would aid in predicting the critical feed rate while drilling the aforementioned composites. The results reveal that critical feed rate in between the range of 0.15–0.18 mm/rev was desirable for minimisation of the onset delamination damage on the composite laminates. However, the stiffer crystalline structure of the flax fibres as compared to the synthetic fibres inflicted toward the presence of delamination damage below the critical feed rate and thrust force values.

Numerical and experimental optimizations of nozzle distance in minimum quantity lubrication (MQL) milling process

Minimum quantity lubrication (MQL) is the efficient and environmentally friendly technology, which is desirable to achieve sustainability during machining process. The nozzle distance has its significance in dominating the MQL spray and the related droplet transportation and penetration. In this paper, the nozzle distance has been optimized for MQL milling process through numerical and experimental methods. A two-way computational method has been employed to solve for the comprehensive flow field and particle trajectories, with the wall condition established on the spray impingement theory. The interactions of air flow rates and spindle rotational speeds on droplet penetration are investigated in details. The optimal ranges of nozzle distance setup obtained by simulation for different conditions were verified via slot milling tests, in which the nozzle distances were selected according to the key points obtained in the numerical process. The cutting force and surface roughness were recorded for the verification of adhesion ability and the related cutting performance. The comparison between numerical simulations and milling experiments has shown great consistency. This paper has achieved better understanding of the nozzle orientation setup and device development in MQL milling process, especially for external MQL. The theoretical basis and scientific instruction have been provided for the optimization of MQL operating parameters in industrial applications.

Influence of rotational speed on mechanical features of thermally drilled holes in dual-phase steel

Thermal drilling is a novel chipless sheet metal drilling process that uses a rotating thermal drill tool to pierce and form a bushing shape hole. In this work, thermal drilling process is successfully employed to drill the DP 600 grade–type galvanized steel with a thickness of 2 mm. The influence of different spindle rotational speeds such as 1600, 2000 and 2400 r/min on the formation of bushing height, surface roughness, microhardness and microstructure of the thermal-drilled holes are investigated in detail. Process parameters such as feed rate, thermal drill angle and workpiece thickness were held constant in order to explore the influence of rotational speed on the quality characteristics of the thermal drilling process. It has been found that the bushing height was improved with increasing of rotational speed, but the petal formation at the outer edge of the bush is decreased. Surface roughness tests indicate that the better surface quality drilled hole could be obtained at the highest rotational speed of 2400 r/min. The microstructural investigation confirmed that a new result of Lüders band marks was formed inside the thermal-drilled holes because high thermal stress and yielding of galvanized steel material.

Robust Chatter Mitigation Control for Low Radial Immersion Machining Processes

Chatter is a typical kind of unstable dynamics often encountered in machining processes, which often results in overcut and rapid tool wear. Hence, chatter phenomenon worsens the surface quality and reduces productivity in milling systems as well. Recent years have witnessed a surging industrial demand of high quality and high efficiency machining. Specifically, for low radial immersion milling situation, large depth of cuts is inevitably needed so as to increase the machining efficiency. To fulfill such a task, this paper develops a robust active control method to mitigate the chatter dynamics of low radial immersion milling processes. The present approach increases the axial depth of cuts, and the improvement is inversely proportional to the radial immersion ratio. Finally, case studies are conducted to show the substantially enlarged stable region in the stability lobe diagram (SLD) spanned by spindle rotational speed and axial depth of cut. Thus, the method can be expected to improve the efficiency of milling processes. Note to Practitioners —This paper seeks to mitigate machining chatters that worsen the workpiece surface quality in high-speed machining processes. To overcome such unexpected effects, traditional passive schemes simply adjust the rotational speed and cutting depth, which do not seek assistance from external power sources. Hence, neither the damping nor stiffness of the system can be changed, and a high maximal material removal rate (MMRR) is arduous to obtain. By contrast, this paper develops a robust active control method to mitigate the chatter dynamics for low radial immersion milling. In the design stage of the milling spindle, two active magnetic bearings (AMBs) are embedded in the tool house as control actuators, which produce extra force to counteract the chatters. In real milling processes, the chatters are detected by the associated inductive displacement sensors around the AMBs, and an uncertainty model is accordingly established with low radial immersion. With the detected vibration displacements, robust active control signals are calculated online, and then fed into the power amplifiers to drive the two AMBs. By this means, a closed-loop active control system is thus established for milling processes, which substantially enlarges the stable region of the SLD spanned by rotational speed and cutting depth. As a result, the proposed active control scheme can be expected to increase the MMRR and, hence, to enhance the productivity of milling processes.

Study on the influence of machine tool spindle radial error motion resulted from bearing outer ring tilting assembly

To reveal the spindle radial error motion characteristics in condition of bearing outer ring tilting assembly, mathematical method on spindle radial error motion were analyzed. Then, in real operation condition the natural frequency of the test rig was investigated. Experimental system and methods were designed to test axial thermal displacement, radial error motion and modal characteristic of spindle in condition of bearing outer ring tilting assembly. Results show that axial thermal extension and radial vertical rising of spindle front-end occurs during thermal displacement test. With the same outer spacer nonparallelism, the synchronous error motion and total error motion generally increase with spindle rotation speed, and reach a peak at certain rotation speed.

Investigation on the fabrication of dicing blades with different sintering methods for machining hard-brittle material wafers

Hard-brittle materials applied in various micro-electromechanical systems should be sliced into miniature and microparts often with complex microstructures. However, it is difficult for bladed dicing to machine those materials without damage because of their hard and brittle properties. This article presents innovative design and fabrication of dicing blades and the associated dicing process optimization, particularly by focusing on the blade wheel fabrication through sintering methods including traditional hot press sintering, vacuum sintering and spark plasma sintering. Four key parameters, namely, the radial wear of the dicing blade, the current of relay, the number of chips larger than 50 μm and the largest chip size, are employed to assess the cutting performance of dicing blades fabricated. The analysis and experimental results indicate that the spark plasma sintering method achieves the lowest number of chips and the smallest chip size due to its rapid spark between metal particles during the sintering process. The spark plasma sintering method can also produce a granular microstructure with sufficient porosities, which results in uniform bonding strength of diamond abrasive grits within the dicing blade. For the dicing process parameters, the back cutting depth has the most obvious influence on the dicing blade tool life, cutting current and slicing damages, while the feed rate is ranked the next. The least influencing parameter is the dicing spindle rotational speed.

Effect of sharpness angle and feeding speed on the surface roughness during milling of various wood species

The article presents research on the effect of the sharpness angle on the quality of machined surface of native wood species (pine, beech, and black locust) and an exotic species called iroko. Four sharpness angle values were analyzed at 25, 40, 45, and 55°. The experiment was conducted on a bottom-spindle milling machine, with a constant spindle rotational speed (6000 min-1) and four feeding speeds of 3.2, 8.3, 12.5, and 16.7 m/min. The influence of sharpness angle, feeding speed, and wood species on the quality of machined surface of wood was determined. The optimum ranges of the sharpness angle were established with respect to wood surface quality. The surface roughness of the samples decreased with decreasing in the sharpness angle in range of 55° to 40°. The optimal value of the angle was 40°, and the roughness increased with increasing feeding speed. It was found that an increase in wood density decreased surface roughness.

Model for the prediction of low-frequency lateral vibrations in drilling process with pilot hole

A model that predicts the appearance of low-frequency lateral vibrations in drilling with pilot hole is proposed in this work. These vibrations, called whirling in the literature, are responsible for the generation of lobe-shaped holes during drilling. The present model considers both the influence of the regenerative effect of vibrations on the cutting forces and the influence of the process damping phenomenon that appears along the main cutting edges. In order to model cutting forces, cutting edges are divided into discrete elements and for each of them oblique cutting model is employed. Specific cutting forces at each cutting edge element are calculated as function of cutting speed and normal rake angle value. A new methodology is developed to analyze the motion equation of the drill in the frequency domain in order to predict the appearance of whirling vibrations during drilling with pilot hole. Regarding the depth of cut and the spindle rotational speed, drilling stability limits against low-frequency lateral vibrations are obtained. Moreover, in the presence of vibrations, the model can predict the whirling frequencies that are excited depending on the established cutting conditions. In addition, the stability model is experimentally validated via drilling tests over pilot holes of different diameters for a wide range of cutting conditions. In order to study the appearance of low-frequency vibrations and to avoid the appearance of other vibrations such as regenerative chatter, the analysis is focused on low spindle speed values. A comparison between predicted vibration frequencies and actual frequencies in measured cutting forces during drilling tests is carried out and a good correlation between them is observed.

Study of Heat Generation and Cutting Accuracy Depending on Spindle Rotation Speed Change in Ultra-Precision Cutting Using ECTS

At present, ultra-precision cutting technology has been studied in Korean research institutes, focusing on development of ultra-precision cutting tool technology and ultra-precision control engineering. However, the developed technologies are still far behind advanced countries. It focuses on metals including aluminum, copper and nickel, and nonmetals including plastics, silicone and germanium which require high precision while using a lathe. It is hard to implement high precision by grinding the aforementioned materials. To address the issue, the ultra-precision cutting technology has been developing by using ultra-precision machine tools very accurate and strong, and diamond tools highly abrasion-resistant. To address this issue, this study aims to conduct ultra-precision cutting by using ECTS (Error Compensation Tool Servo) to improve motion precision of elements and components, and compensate for motion errors in real time. An IR camera is used for analyzing cutting accuracy differences depending on the heat generated in diamond tools in cutting to examine the heat generated in cutting to study cutting accuracy depending on generated heat.

Electrochemical micromachining of titanium microstructures in an NaCl–ethylene glycol electrolyte

Titanium and its alloys are widely used in the aerospace and biomedical industries owing to their outstanding corrosion resistance and good biocompatibility. Wire electrochemical micromachining (Wire-ECMM) is a promising method for fabricating titanium microstructures because of the absence of residual stress and tool wear. The electrochemical dissolution characteristics and polarization curves of titanium in aqueous and ethylene glycol-based electrolytes are obtained and analyzed. The effects of electrolyte anion species on electrochemical machining of pure titanium are experimentally evaluated. An NaCl–ethylene glycol electrolyte is selected to explore the influences of various process parameters on machining accuracy in ECMM. A rotary helical electrode is utilized to accelerate the removal of electrolysis products and thereby improve the refreshment of the electrolyte. Finally, titanium microstructures of high surface quality are fabricated with high precision using ECMM at a voltage of 11 V, a spindle rotation speed of 4000 rpm, a pulse frequency of 200 kHz, a duty ratio of 30%, and an electrode feed rate of 0.3 μm/s.

Evaluation of mechanical properties of friction stir welded commercially pure aluminium

In this study, friction stir welding (FSW) of commercially pure aluminium is carried out. The main defects existing in this process are cavity, irregular material flow due to unsuitable selection of welding parameters. In this study, to reduce the defects by selecting suitable parameter and welding quality determined by mechanical testing methods and non-destructive testing methods. Welding is done with preheating the base metals and without preheating the base metals and their effects are analyzed with similar parameter. The parameters considered for this work are spindle rotational speed (rpm), tool travel speed (mm/min) and axial force (kN). The experimental results are evaluated by Destructive Test and Non-destructive test methods. The characterization study is performed by Optical microscope and Scanning Electron microscopy (SEM).