International Journal of Mechatronics and Manufacturing Systems (10 papers in press)
Experimental Investigations into Rotary Magnetic Field and Tool assisted Electric Discharge Machining using Magneto Rheological Fluid as Dielectric
by Lokesh Upadhyay, M.L. Agarwal, Pulak M. Pandey
Abstract: The present study focuses on the development of an electric discharge machining method that used magneto rheological fluid as dielectric and rotary magnetic field assisted electric discharge tool. The work aims to improve performance of electric discharge machining by utilizing the combined effect of magneto rheological fluid with rotating electrode and magnetic field. This developed hybrid machining process has been designed to attain higher material removal rate for improving production rate. In this process, the surface roughness has been found higher as compared to when magnetic field and tool was kept stationary. M2 grade high speed steel workpiece was used for parametric study. The experimentation was performed to evaluate the effect of percentage contribution of alumina particles, discharge current, duty cycle, and pulse on time effect on material removal rate and surface roughness. The experimental findings demonstrated that EDM process with rotary magnetic field and tool with magneto rheological fluid as dielectric resulted in an increased material removal rate as compared to EDM with static magnetic field and tool. The following findings were found significant for a certain limit of carbonyl iron percentage in magneto rheological fluid.
Keywords: Electric discharge machining; roughness; magneto rheological fluid; alumina.
Modeling and Analysis of Tool Deflections in Tailored Micro End Mills
by Samad Nadimi Bavil Oliaei, Yigit Karpat
Abstract: The deflection of micro end mills has a detrimental effect on surface quality of the machined micro components and adversely affects the achievable dimensional and geometrical tolerances. In this paper, the analysis and modeling of tool deflections of tailored micro end mills have been considered. The tool deflections are obtained using analytical models as well as finite element simulations, and verified using a dedicated measurement setup, which uses a capacitive sensor with a nanometer resolution for static tool deflection measurements. The optimization of the micro end mill geometry has been performed to determine optimum neck taper angle and transition radius of the single edge micro end mill to have minimum tool deflections. With the developed model, tool failure predictions for a given process parameter set can be performed and it can be used for better micro milling process planning.
Keywords: Micromilling; Tailored Micro End Mill; Tool Deflection; Optimization; Tool Failure.
Performance of different abrasive tools in electrochemical honing of coated surfaces
by Harpreet Singh
Abstract: This paper highlights on the honing characteristics of various abrasive tool materials during the precision finishing of EN52 coated surface of the engine valve face using electrochemical honing (ECH) process. The investigation on various abrasive tool materials in ECH are first proposed, and it may help to enhance the process performance characteristics of ECH. It is a new technique, which in spite of being used in some industrial plants, in particular to smooth surfaces and is still not fully described due to the variety of the factors affecting the process. More information about the process is required, especially the honing related parameters, such as abrasive tool pressure, abrasive material, and abrasive size. Special shaped honing tools were designed and fabricated to study the present aspects. Two different types of abrasive tool material (Al2O3 and NiCr) for honing operation were used while ECH of EN52 work surface. The results of the experiments are finally furnished with the aim to generalize a useful guideline for the user to enable proper selection of conditions for obtaining good surface quality.
Keywords: abrasive tool; ECH; EN52; engine valve face; HVOF; product recovery; surface finish.
Online correction of thermal errors based on a structure model
by Xaver Thiem, Bernd Kauschinger, Steffen Ihlenfeldt
Abstract: This article deals with the structure model based correction approach for thermal errors at machine tools. Structure models are physically based models of the thermo-elastic behaviour of machine tools. Input data of the model are technological loads captured in the machine control. The article focuses the experimental validation of the online correction on the example of a demonstrator machine (parallel kinematic). A finite element model with reduced model order is used as structure model. Besides the implementation of the correction approach the parameter adjustment of the model is described. The conducted experiments show that up to 87% of the maximal thermo-elastic error of the ball screw axes of the machine can be compensated with the proposed correction approach.
Keywords: thermal error; machine tool; correction; compensation; structure model; online; control; parallel kinematics; accuracy; ball screw; FEM; finite element method; temperature; deformation.
Special Issue on: ICHSM2016 Advances in Machine Tools and Monitoring Systems
Diversity of Assembly Error Migration and Its Solution Model for Heavy Duty Machine Tool
by Bin Jiang, Yunpeng Gu, Tiantian He, Shouzheng Sun, Chongmin Jiang
Abstract: Aiming at the ever-changing assembly error along with operation in the large scale assembly space, the diversity of machine tool assembly error migration and its operation route are characterized by making use of the correspondence relationship between joint surface error and operation distance. The formation and retention of assembly error are respectively revealed by the forward migration and the reverse migration of assembly error. Furthermore, the delayed step function of assembly error migration is constructed to recognize the potential control operation of error migration. Based on the response surface method, the solution model of assembly error migration is established to reveal the diversity of assembly error migration process and the effect of multiple operations. Finally, the design method of assembly process about heavy duty machine tool is proposed, and its effectiveness is verified by gantry-moving type turning-milling machining centre.
Keywords: heavy duty machine tool; assembly error; assembly operation; error migration; delayed step function; response surface method.
Experimental Investigation on Surface Quality in Ultrasonic Vibration Assisted High Speed Grinding of BK7 Optical Glass
by Ming Zhou, Peiyi Zhao, Huang Shaonan
Abstract: Knowledge of surface formation mechanism plays a key role in implementing precision machining of optical glass. In order to evaluate the surface quality and to explore surface formation mechanism, in this paper, ultrasonic vibration assisted grinding (UVAG) experiments were carried out on BK7 optical glass by employing diamond wheel. Quite a few micro and macro brittle-fractured pits of different shapes, sizes and morphologies were observed on machined surfaces by using scanning electron microscope. Spindle rotation speed, feed rate, grinding depth and ultrasonic vibration amplitude had be found to exert significant effects on the surface generation and machined surface roughness in ultrasonic vibration assisted grinding of this kind of materials. It was also demonstrated that the value of machined surface roughness would become much smaller if the pits size was small. Based on the observation and classification of pits morphologies, the machined surfaces forming mechanism was extensively investigated in this work.
Keywords: Surface formation; Optical glass; Ultrasonic vibration; Grinding.
Characteristics of the self-organization in high-speed turning of high-strength alloy steel
by Youfei Fang, Guangming Zheng, Zongwei Niu, Xiang Cheng, Yingzhao Yu
Abstract: Tool life and wear mechanism of the multi-layer coating tools are studied by high-speed turning of high-strength alloy steel 300M. Micro-morphology and element distribution of the tool worn surface are observed through scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). The emphasis is on the self-organization characteristics of the microcosmic surface of worn tools. The results show that adhesive layer and oxygen-containing film are the characteristics of self-organization structures of the coating tools. The CVD-TiCN-Al2O3 coating is suitable for high-speed turning of 300M. The wear mechanisms of the coated tool include adhesion, abrasion, diffusion, oxidation, coating flaking and chipping. The adhesive wear is found at various cutting stages. And the formation of self-organization structures is determined by the diffusion and oxidation. The coated tool of creating self-organization structures exhibits the higher wear resistance, especially intensive tribological compatibility which can extend the stable wear stage.
Keywords: tool life; wear mechanism; coated tool; self-organization; oxygen-containing film; 300M.
Background Texture Suppression and Defect Extraction of High-Speed Milling Surface Image
by You-hang Zhou, Yong Li, Xian-wei Shi, Tuo Kong
Abstract: This paper proposed a method to extract the machine defect from the surface images of high-speed milling workpiece, and reduced the impact of workpiece surface background texture. Firstly, Wiener Filtering method is used to denoise the high-speed milling workpiece surface images. Then the potential texture images are obtained by using the nonnegative matrix decomposition algorithm for learning denoising images unsupervisedly. Next, original images and potential texture images are used to convolute with the imaginary part function of Gabor filter respectively, and apply Image Differencing method to obtain the energy difference images. The binary defect images are extracted after the Threshold Segmentation method is applied. Application example shows the capability of this method to extract machine defect.
Keywords: machine defect; background texture; Wiener Filtering; Threshold Segmentation.
Synthesis and characterization of AlMgB14 and AlMgB14-Ni3Al composites
by Zhou Yumei, F.L. Zhang, K. Bai, T. Zhang, H.P. Huang, S.H. Wu, S.M. Luo
Abstract: Materials with higher hardness and lower friction coefficients with steel have been proposed as candidates for strategic use in the application fields of cutting tool and friction reduction materials. Aluminum magnesium boride (AlMgB14) and its composites are excellent candidates for these purposes. The impurity of MgAl2O4 is normally formed in the synthesized AlMgB14 because of oxygen and oxide involved from raw materials and processing, so an extra amount of Al and Mg beyond the stoichiometric ratio of AlMgB14 were introduced into the raw elemental powders to synthesize AlMgB14 in an atmosphere of argon at 1500 ℃. The AlMgB14-Ni3Al composites were also synthesized by hot pressed sintering at 1450 ℃ and 1600 ℃ separately. The microstructure and mechanical properties of AlMgB14 and AlMgB14-Ni3Al composites were also examined. The results showed that extra addition of 5 wt.% Al and 5 wt.% Mg can reduce the production of MgAl2O4 in the formation of AlMgB14. Besides of AlMgB14 and MgAl2O4 , Ni3Al and NiAl are identified in the AlMgB14-Ni3Al composites, the hardness and fracture toughness of AlMgB14-Ni3Al composites are decreased with higher content of Ni3Al due to the present of Ni3Al and NiAl phase.
Keywords: AlMgB14; Ni3Al; Microstructure; Hot pressed sintering; Mechanical properties.
Characterization for Differential Wear between Left and Right Flank Faces in Turning Large Pitch Internal Thread
by Bin Jiang, Tong Xu, Zhe Li, Yunpeng Gu, Tiantian He
Abstract: In turning large pitch internal thread, there are obvious differences between the wear on the left and right flank faces of the same cutting tool, which decrease the tool life and the consistency of machining surface quality of threads. The force equations of tools left and right cutting edges are used to reveal their differences in mechanical condition. Adopting axial direction cutting method, the flank wear experiment is carried to obtain its characteristics of left and right cutting edges and the time-domain signals of tool vibration. During the formation of differential wear of left and right flank faces, the stress state and the vibration of cutting tool are analyzed. Finally, the distribution functions of flank wear widths are established to reveal the change characteristics of wear width along the cutting edge and the cutting stroke and quantitatively describe the wear processes and differences of left and right flank faces.
Keywords: turning; axial stratified cutting; internal thread; large pitch; tool; left and right cutting edges; left and right flank faces; different wear; contact relationship between tool and workpiece; cutting stroke; length of cutting edge; wear width; distribution function.