Improving machining stability of AISI-4140 with magnetic field

Author(s):  
Mehmet Alper Sofuoglu ◽  
Fatih Hayati Çakir

Several methods have been developed in order to improve the traditional machining processes and machining outputs. In this study, the effect of the magnetic field on the turning process was investigated. AISI-4140 was machined with different cutting speeds and magnetic flux density magnitudes. The magnetic field was generated with neodymium magnets. Machining stability, surface roughness, and maximum cutting temperature were measured. Additionally, chip shapes were examined. The machining stability was determined by measuring the vibration amplitude and other vibrational parameters (natural frequency, stiffness, and damping coefficients). Conventional turning and magnetic assisted turning were performed under the same cutting parameters consecutively, and the results were compared. According to the results, it was observed that neodymium magnets attached to the cutting tool improve machining stability and damping properties. Surface roughness was decreased between 6%–10% in magnetic assisted turning. Furthermore, it has been observed that the maximum cutting temperatures have been increased between 10%–45% in the magnetic assisted machining. Besides, it can be said that magnets contribute to improving chip control by collecting the chips on them while machining AISI-4140 steel.

2020 ◽  
Vol 38 (11A) ◽  
pp. 1593-1601
Author(s):  
Mohammed H. Shaker ◽  
Salah K. Jawad ◽  
Maan A. Tawfiq

This research studied the influence of cutting fluids and cutting parameters on the surface roughness for stainless steel worked by turning machine in dry and wet cutting cases. The work was done with different cutting speeds, and feed rates with a fixed depth of cutting. During the machining process, heat was generated and effects of higher surface roughness of work material. In this study, the effects of some cutting fluids, and dry cutting on surface roughness have been examined in turning of AISI316 stainless steel material. Sodium Lauryl Ether Sulfate (SLES) instead of other soluble oils has been used and compared to dry machining processes. Experiments have been performed at four cutting speeds (60, 95, 155, 240) m/min, feed rates (0.065, 0.08, 0.096, 0.114) mm/rev. and constant depth of cut (0.5) mm. The amount of decrease in Ra after the used suggested mixture arrived at (0.21µm), while Ra exceeded (1µm) in case of soluble oils This means the suggested mixture gave the best results of lubricating properties than other cases.


Sensors ◽  
2021 ◽  
Vol 21 (7) ◽  
pp. 2522
Author(s):  
Guangdou Liu ◽  
Shiqin Hou ◽  
Xingping Xu ◽  
Wensheng Xiao

In the linear and planar motors, the 1D Halbach magnet array is extensively used. The sinusoidal property of the magnetic field deteriorates by analyzing the magnetic field at a small air gap. Therefore, a new 1D Halbach magnet array is proposed, in which the permanent magnet with a curved surface is applied. Based on the superposition of principle and Fourier series, the magnetic flux density distribution is derived. The optimized curved surface is obtained and fitted by a polynomial. The sinusoidal magnetic field is verified by comparing it with the magnetic flux density of the finite element model. Through the analysis of different dimensions of the permanent magnet array, the optimization result has good applicability. The force ripple can be significantly reduced by the new magnet array. The effect on the mass and air gap is investigated compared with a conventional magnet array with rectangular permanent magnets. In conclusion, the new magnet array design has the scalability to be extended to various sizes of motor and is especially suitable for small air gap applications.


2021 ◽  
Vol 11 (10) ◽  
pp. 4567
Author(s):  
Xiaoqing Zhang ◽  
Yaowu Wang

An effective method is proposed in this paper for calculating the transient magnetic field and induced voltage in the photovoltaic bracket system under lightning stroke. Considering the need for the lightning current responses on various branches of the photovoltaic bracket system, a brief outline is given to the equivalent circuit model of the photovoltaic bracket system. The analytic formulas of the transient magnetic field are derived from the vector potential for the tilted, vertical and horizontal branches in the photovoltaic bracket system. With a time–space discretization scheme put forward for theses formulas, the magnetic field distribution in an assigned spatial domain is determined on the basis of the lightning current responses. The magnetic linkage passing through a conductor loop is evaluated by the surface integral of the magnetic flux density and the induced voltage is obtained from the time derivative of the magnetic linkage. In order to check the validity of the proposed method, an experiment is made on a reduced-scale photovoltaic bracket system. Then, the proposed method is applied to an actual photovoltaic bracket system. The calculations are performed for the magnetic field distributions and induced voltages under positive and negative lightning strokes.


2020 ◽  
Vol 22 (1-2) ◽  
pp. 58-64
Author(s):  
Teodora Gavrilov ◽  
◽  
Karolina Kasaš-Lažetić ◽  
Kristian Haška ◽  
Miroslav Prša

In this paper, the analysis of magnetic field distribution of overhead mixed power line (20 kV/0.4 kV) supported by reinforced concrete towers, named MNL-12 is presented. The impact of ferromagnetic, conductive parts of the pylons (reinforcing bars, billets and cross arm beams) on magnetic field distribution is investigated. The numerical calculations were performed in COMSOL Multiphysics program package on simplified 2D model. The main goal of the calculations was to examine the impact of currents induced in ferromagnetic conductive parts on magnetic field produced by currents in the power system’s conductors. The calculation results are presented graphically, as the diagrams of the magnetic flux density magnitude distribution in the tower plan, normal to the system’s axe. The calculation results demonstrated that the magnetic field of induced currents decreases the magnetic field produced by the currents of overhead power system.


2021 ◽  
Vol 1018 ◽  
pp. 111-116
Author(s):  
Yan Hua Zou ◽  
Hui Jun Xie

The traditional magnetic abrasive finishing (MAF) process, the magnetic flux density at the bottom of the magnetic pole is unevenly distributed, resulting in poor uniformity of the finished surface. Therefore, it is proposed to improve the surface quality by attaching a magnetic plate at the bottom of the workpiece to improve the magnetic field distribution. It is confirmed by simulation that the magnetic field distribution at the bottom of the magnetic pole is effectively improved after the magnetic plate is attached. It is proved through experiments that the magnetic plate-assisted MAF process can obtain a smoother surface. The experimental results show that the surface roughness of the glass lens improves from 246 nm Ra to 3 nm Ra through the magnetic plate-assisted MAF process within 45min.


Author(s):  
János Farkas ◽  
Etele Csanády ◽  
Levente Csóka

A number of equations are available for predicting the output of machining processes. These equations are most commonly used for the prediction of surface roughness after tooling. Surface roughness can be influenced by many factors, including cutting parameters, tool geometry and environmental factors such as the coolant used. It is difficult to create a universally applicable equation for all machining because of the variations in different materials' behaviours (e.g. metal, wood, plastic, composite, ceramic). There are also many differences between the various types of machining process such as the machining tools, rotational or translational movements, cutting speeds, cutting methods, etc. The large number of parameters required would make such an equation unusable, and difficult to apply quickly. The goal is thus to create a simple formulation with three or four inputs to predict the final surface roughness of the machined part within adequate tolerances. The two main equations used for this purpose are the Bauer and Brammertz formulas, both of which need to be optimised for a given material. In this paper, the turning of thermoplastics was investigated, with the aim of tuning the Bauer formula for use with thermoplastics. Eleven different plastics were used to develop a material-dependent surface roughness equation. Only new tooling inserts were used to eliminate the effects of tool wear.


Author(s):  
Ping-Hsun Lee ◽  
Jen-Yuan (James) Chang

Abstract In this paper we proposed a platform for measuring shear force of magnetorheological (MR) fluid by which the relationship of yield stress and magnetic flux density of specific material can be determined. The device consisted of a rotatable center tube in a frame body and the magnetic field was provided by two blocks of permanent magnets placed oppositely outside the frame body. The magnitude and direction of the magnetic field were manipulated by changing the distance of the two permanent magnets from the frame body and rotating the center tube, respectively. For determining the magnetic field of the device, we adopted an effective method by fitting the FEM (finite element method) result to the measured one and then rebuilt the absent components to approximate the magnetic field, which was hardly to be measured simultaneously as different device setup were required. With the proposed platform and analytical methods, the drawing shear force and the corresponding yield stress contributed by MR fluid could be evaluated in respect to the magnitude and direction of given magnetic flux density with acceptable accuracy for specific designing purposes without a large, complex, and expensive instrument.


2019 ◽  
Vol 20 (6) ◽  
pp. 620 ◽  
Author(s):  
Farhad Najarian ◽  
Roozbeh Alipour ◽  
Abbas Razavykia ◽  
Ali Farokhi Nejad

Drilling is one of the most important machining processes which are currently carried out on fiber-reinforced composites. These composites possess a layered structure and different properties through their thickness. When drilling such structures, internal defects like delamination occur, caused by the drilling forces and their uneven distribution among the plies. The current study investigates the effect of magnetic field on drilling process of basalt/epoxy composite laminate in order to reduce delamination and the thrust force and improve some hole quality parameters i.e. roughness and cylindricity. A comparison is made between the responses for both normal drilling and drilling with applying a magnetic field. For this purpose, after finding the best combinations of normal drilling parameters, magnetic field is applied to the different configurations of solenoids on the setup of the drilling process. The results highlighted that using different magnet solenoids on the top and the bottom of drilling zone reduces the delamination and can obtain better roughness and cylindricity with lower damage.


2011 ◽  
Vol 121-126 ◽  
pp. 2706-2709
Author(s):  
Dan Jiang ◽  
Ping Yang ◽  
Kun Jiang

As a type of solid state switch, MR (magnetoresistive) sensor detects the air cylinder piston’s position in pneumatic control system. The construction and working principle of the air cylinder with MR sensor are introduced. Using 2-D magnetic field finite element analysis (FEA) method, the magnetic field distribution of air cylinder with piston motion is analyzed. Simulation results are given. The magnetic flux density characteristics are compared between piston wear or not.


Author(s):  
Alper Uysal

Polymer composite materials can be produced by reinforcing carbon black, carbon fiber, graphite, graphene, metals and metal oxides, nanotubes, and so on. These types of composite materials can be employed in applications demanding electrical conductivity besides high specific strength and stiffness properties of polymer materials. In the literature, there is a lack of knowledge on the examination of drilling of particle-reinforced composite materials. In this study, drilling of pure polypropylene and carbon black–reinforced polypropylene composite material was investigated at different drill point angles, cutting speeds, and feeds. The cutting temperature of drill point and surface roughness of holes were examined. The experimental studies were designed by L27 full-factorial design, and analysis of variance statistical method was performed. According to the results, cutting temperature increased and surface roughness decreased with the increase in the cutting speed and feed and decrease in the drill point angle.


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