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The precision turning process has attracted enormous interest in the standardized and mass production of micro-shafts because it produces more efficiency and lower cost compared with the electrical-discharge machining method and micro-machining method. However, there are many critical factors that influence the dimensional accuracy of micro-shafts, such as the error of workpiece deformation, cutting force, and tool setting error. In this paper, a novel error compensation method was proposed to improve the dimensional accuracy of micro-shafts manufactured with the conventional precision machine tool, based on the constant force cutting method and tool path planning. Firstly, a cutting force model was established considering the effect of the tool nose radius, and the finite element method was used to simulate the turning process and predict the workpiece deformation. Secondly, an error analysis model was created by taking tool setting error, workpiece deformation error, and multi-process cumulative error into account, and the optimized tool path and cutting parameters were obtained. Finally, a series of turning experiments were carried out to verify the error compensation strategy and the cutting force model. The results show that the dimensional error of the micro-shafts with a large length-diameter ratio (l = 5 mm, d = 0.4 mm) can be reduced by 90% by means of the proposed error compensation strategy. In addition, the maximum prediction error of cutting forces is less than 8.6%, and the effect of cutting parameters on cutting forces can be concluded as “feed rate > depth of cut > spindle speed.”

Friction modeling between the tool and the workpiece plays an important role in predicting the minimum cutting thickness during TC4 micro machining and finite element method (FEM) cutting simulation. In this study, a new three-region friction modeling is proposed to illustrate the material flow mechanism around the friction zone in micro cutting; estimate the stress distributions on the rake, edge, and clearance faces of the tool; and predict the stagnation point location and the minimum cutting thickness. The friction modeling is established by determining the distribution of normal and shear stress. Then, it is applied to calculate the stagnation point location on the edge face and predict the minimum cutting thickness. The stagnation point and the minimum cutting thickness are also observed and illustrated in the FEM simulation. Micro cutting experiments are conducted to validate the accuracy of the friction and the minimum cutting thickness modeling. Comparison results show that the proposed friction model illustrates the relationship between the normal and sheer stress on the tool surface, thereby validating the modeling method of the minimum cutting thickness in micro cutting.

Single-point diamond cutting is an efficient method to fabricate microlens arrays (MLAs). However, machining MLAs at the microscale with high dimensional accuracy and a smooth surface finish is a difficult task. In this study, a method of profile cutting is proposed to machine MLAs on electroless nickel–phosphorus (Ni–P) plating. To improve the dimensional accuracy of MLAs, a precision tool setting method is introduced, via which the precision of MLA sag can be controlled to within 20 nm. In addition, the formation mechanism of corrugation defects is studied via a finite element (FE) simulation of the wedge nano-cutting process and a cutting experiment of concentric ring grooves. By optimizing the tool settings and the machining parameters, high-quality MLAs with apertures of Φ100 μm can be created.

As an unfavorable factor of machining process, chatter threatens the machined quality of workpiece, which determines the assembly and fatigue performance of the workpiece. During the interaction between machine tool and thin-walled workpiece, the process damping effect, multiple modes response and dynamic changes caused by the material removal of the in-process workpiece (IPW) will make the machining process more complicated and introduce great difficulties to dynamic modeling and performance prediction. In this paper, we considered the process damping determined by the indentation volume between flank face of milling tool and machined surface, and used multi-mode model to describe this behavior. In order to establish the assembled material removal model of the IPW dynamics with multiple modes, the structure dynamic modification (SDM) and finite element method (FEM) were combined together. The updated third-order full discretization method was applied to solve the dynamic equation in modal space. Then, the three-dimensional stability lobe diagrams (SLDs) with and without material removal along the tool path were obtained respectively by enveloping multiple modes of the IPW and milling tool together. Finally, the cutting tests were carried out. The experiments showed that the assembled model could predict the dynamics of IPW accurately, and the proposed stability analysis model was relatively close to experimental results. Besides, the modes of thin-walled workpiece with weak rigidity do not always play a dominant role in the process of machining. Although the material removal rate is limited by considering the multiple modes of the system, the processing quality can be ensured.

Nowadays, micro engine miniaturization is one of the most challenging issues, especially for the design and fabrication of the high-power-density micro Wankel engine. With the decrease of the size of the micro engine, the problem of the heat deformation of the cylinder becomes more serious. In this paper, a micro Wankel engine with microtextures on the outer surface of the cylinder is designed and manufactured to diffuse the heat dissipation and regulate the temperature gradient, so as to increase the power output density. First, a series of finite element simulations are conducted to design a type of ideal surface microtexture. Then, the machining condition is optimized to fabricate microtextures by micro cutting on the cylinder surface by studying the processing parameters. Finally, the performance of the new micro Wankel engine in terms of the temperature gradient regulation and the mechanical power output is tested and compared with that of the un-textured micro engine. The comparison results show that temperature of the textured micro engine was dropped from 185 &deg, C to 125 &deg, C and the mechanical power output increased by 10.74% from that of its un-textured counterpart, verifying the proposed methods for temperature gradient regulation.

The serrated chip is a remarkable characteristic in the machining of the Ti-6Al-4 V alloy, but its formation mechanism is not completely understood. Finite element modeling is an effective method for studying the complex thermo-mechanical problems that occur during the machining process. The constitutive model plays a key role in the simulation, and Johnson-Cook (JC) model is the most commonly used model. However, the JC model neglects the coupled effects of the strain, strain rate, and temperature, and the material is assumed to be homogeneous. Thus, the JC model is applicable for studying macroscale machining. In fact, cutting is a complex thermo-mechanical process, and there are material defects in the Ti-6Al-4 V alloy. First, a modified JC model is proposed based on the THAN law, which is derived from material defects considering the coupled effects of the strain, strain rate, temperature, and strain softening. Then, the serrated chip morphology and cutting force predicted by the JC-THAN model are compared with experimental data. Finally, the serrated chip formation mechanism from macroscale machining to microscale machining is analyzed considering the material defects based on the JC-THAN model, and the dominated formation mechanism at each scale is found.

n view of the influence of cutting heat and cutting force on the machining precision of micro-machining, this paper carries out micro-milling temperature measurements and deformation measurement tests based on the theoretical model of temperature field distribution of workpiece and the simulation model of workpiece deformation, providing technical basis for the high-precision machining of precision micro-parts. A theoretical model for the description of the increase in the cutting temperature of the workpiece is established prior to using an inverse evaluation method for solving the heat source intensity iteratively. During the finite element analysis of the distribution of the temperature field and heat distortion, the process of the heat transfer is simplified as a process of applying a series surface heat source to workpiece. Besides, this paper carried on a series of micro-milling experiments, used a fast-response thermocouple which has a property of self-renewal for the measurement of the change of the workpiece temperature, the response time of the applied thermocouple is within the magnitude of microsecond, and then, a high-frequency amplifier and an electric potential acquisition equipment were used to gain the transient temperature in the cutting area; meanwhile, a dynamometer is applied to measure the three-directional forces, and finally, the workpiece deformation would be measured by the Keyence microscope. Through the comparison of the simulated temperature and deformation with the experimental results, the simulation model showed considerable reliability.

Chalcogenide glass (ChG), as an alternative material in place of single-crystal germanium, is increasingly used in thermal imaging, night vision, and infrared guidance systems, etc., owing to their excellent formability through precision glass molding (PGM). The deformation mechanisms of these glasses at the molding temperature involve elasticity, plasticity, and viscous flow, which call for a new theoretical model to assist the design of PGM process. This paper investigates the thermo-mechanical properties of Ge22Se58As20 at the temperature above its softening point and establishes a new elastic-viscoplasticity model to describe its thermo-mechanical behaviors. After determining the model parameters through cylindrical compression tests, the new constitutive model is implemented in finite element method (FEM) of PGM to form an aspheric ChG lens. And the agreement of displacement-time curves between experimental and simulation results exhibit the validity of the proposed elastic-viscoplastic constitutive model.

A three-dimension (3D) finite element (FE) end milling model with equivalent homogenous material (EHM) model, which was drawn from the quasi-static and SHPB (Split Hopkinson pressure bar) tests, has been developed by using ABAQUS/Explicit in order to describe the machining process of SiCp/Al6063/30P composites. The model is verified by milling experiments and it is found that the predicted milling forces at different combinations of feed rate and rotation speed are consistent with those in milling experiments, and the prediction error of the peak value of F y and F x can be controlled within 20%. Moreover, the general shapes of the predicted chips are very similar to the experimental ones, but the application of EHM material model leading to the limitation of the simulated chip morphology such as cracks on chip contact surface and free surface caused by the existence of hard SiC particles cannot be described. Hence, further microstructure-level 3D FEM model which can reveal the interactions between particles and matrix and their effect on the chip formation mechanism of SiCp/Al6063composites becomes very necessary.

Micro optical elements with complex shapes are needed increasingly in optical, optoelectronic and biomedical industries. Since glass molding process is an effective approach to fabricate microstructures, and its surface quality strongly depends on the filling capacity of glass at high temperature. To improve the formability and reduce adhesion between the glass and the mold at high temperature, ultrasonic vibration is applied to improve the formability in the molding process. Fundamental experiments are carried out to test the effectiveness of ultrasonic vibration on friction force decrease and a bonding model on the glass-mold interface at elevated temperature is proposed. Finite element method (FEM) simulation and glass molding experiments are conducted to evaluate the improvements of material formability brought about by ultrasonic vibration. The results show that the ultrasonic vibration can significantly lower the friction force and increase the glass formability.

Microgrooves with a pitch at wave length level are increasingly needed in the optical system. Conventionally, the accuracy is low in microgroove forming due to the incomplete filling in the cavity of microgroove mold, as well as the surface flaws appearing with the adhesion of the resin material to the mold surface. In this research, the response behavior of resin material subjected to alternating stress is resolved based on Generalized Maxwell model. Finite Element Method (FEM) simulation is carried out to test the interface contact between the resin and the mold. Microgrooves forming effects under the pressing condition without and with ultrasonic vibration are studied. An ultrasonic vibration assisted pressing machine is developed and used to fabricate microgrooves on resin surface by using the Nickel Phosphorous (Ni–P) mold. The results show that the ultrasonic vibration can significantly decrease the resin dynamic viscosity as well as contact time with the mold, and achieve better forming accuracy and surface quality.

To manufacture high precision optical glass microstructures, finite element simulation and experiments of precision glass molding (PGM) are carried out to study the influence of relaxation effect on internal stress and deformation of the glass material. Two kinds of microstructures including microgrooves and micropyramids are fabricated by PGM. First, a two-dimensional axisymmetric finite element model of the PGM is established, and three kinds of molding schemes are put forward and analyzed, including quick molding and holding for a period of time, molding with low speed, molding by gravity. The advantages and disadvantages of the three schemes are also analyzed. Second, the microgrooves are fabricated using the scheme of molding by gravity, and then the existing problems are discussed. Finally, the micropyramids are fabricated by the low speed molding method, and the forming profiles are compared.

Microgrooves with a pitch at wave length level are increasingly needed in the optical system. Conventional, the microgroove forming accuracy is low due to the incomplete filling of the material in the cavity of microgroove mold, and surface flaws occur easily due to the adhesion of the resin material to the mold surface. In this research, the response behavior of resin material subjected to alternating stress is resolved based on Generalized Maxwell model. Finite Element Method (FEM) simulation is carried out to test the microgroove forming effects under the pressing condition without and with ultrasonic vibration. An ultrasonic assisted pressing machine is developed and used to fabricate microgrooves on methacrylic resin surface. Form accuracy and surface quality of microgrooves are confirmed to be improved by comparing the ultrasonic assisted pressing with the conventional forming.

The thermal field and the temperature change of the optical waveguide core of thermo-optic (TO) switch generated by heating the Al electrode are simulated using the finite-element method (FEM), and the steady-state temperature distribution and time response of TO switch are presented. Our research covers several conditions, including different electrode heater widths, upper cladding layer thicknesses, under cladding layer materials and different structures. The results turn out that the performance of the TO switch can be improved using the polymer/silica hybrid and the air trench waveguide structures. The TO switch was fabricated and the surface thermal field distribution was measured. A good agreement between the experimental results and theory analysis has been observed.

In precision manufacturing industry, requirements for surface quality are very high. It is important to accurately predict the machined surface errors to reduce manufacturing costs and lead times as well as develop fixturing scheme to optimize machining quality. This paper presents a contribution for predicting the machined surface errors where fixture-workpiece system dynamic effects during milling process are considered. The combined effect of clamping and milling on machined surface errors prediction is taken into account, and finite element analysis is developed to analyze the workpiece deformation. In finite element analysis environment, the static analysis and explicit dynamic analysis are used to calculate the static deformation due to clamping force and the dynamic deformation due to milling force. Milling forces are applied to the manufacturing points step by step. The chip removal effect is taken into account based on element death technique, and every fixture locator is modeled as a virtual spring-damper system to emulate the fixture-workpiece contact points. The developed methodology has been verified by a set of end milling experiments for ten fixture layouts. The measured and predicted results are in good agreement, and the results also illustrate that the closer the triangle formed by the three locators in the primary datum is to an equilateral triangle, the smaller machined surface errors will be.

At mesoscale, the blade of micro impeller with Ti-6Al-4V titanium alloy (micro thin wall with mixed boundaries) is a thin-walled structure, characterized by small size, low stiffness, high surface precision, complex boundaries, and difficult-to-control machining deformation. To control and reduce the deformation of micro thin wall, it is necessary to study the micro-deformation mechanisms during milling micro thin-wall parts. In side milling of micro thin wall with mixed boundaries, the micro thin wall suffers from dynamic alternating forces, and the deformation modes are complex, so the direct and accurate theoretical modelling is difficult to make. Since the feed speed in milling micro thin wall is less, the small deformation of micro thin wall can be described based on the flexure deformation model of the thin plate subjected to elastic loadings. Firstly, accompanied by the reciprocal theorem of work for a curved thin plate, Kirchhoff-Love small deformation model of micro thin wall is used to establish the deformation equation and boundary conditions of micro thin wall with mixed boundaries under concentrated milling forces. Thus, the obtained boundary conditions are mainly applied to the subsequent finite element simulation of three-dimensional milling deformation of micro thin wall. Then a three-dimensional deformation simulation of the micro thin wall under different milling parameters is carried out by considering the micro-walled structure, material elasto-plastic constitutive model, the stiffness and geometric structure of micro milling tools in finite element method. In the workpiece constitutive modelling, considering the strain gradient plastic model in micro milling of Ti-6Al-4V titanium alloy, the workpiece plastic constitutive model is modified by introducing the intrinsic characteristic length of the material to describe the size effects in mesoscale micro milling. Finally, a series of the corresponding experiments on the milling of titanium alloy micro thin walls are carried out. By comparing and analyzing the experimental values and finite element numerical results of the micro thin-walled deformation, the micro deformation mechanisms in milling of thin wall are revealed. It also verifies the accuracy and effectiveness of this established milling finite element model of thin wall, and provides theoretical basis and technical support for controlling the milling deformation of micro thin-walled parts.

A multi-phase two-dimension finite element model has been developed by using ABAQUS/Explicit in order to describe the effect of reinforcement particles’ existence in SiCp/Al6063 composites on the machining process. It is used to simulate the high-speed milling process of high volume fraction SiCp/Al6063 composites. As comparison, the same machining process of matrix Al6063 is simulated with the HEM (homogenous equivalent material) model. These two models are verified with quasi-orthogonal slot milling tests. It is assumed that the variation of predicted milling forces with the feed rate is consistent with the experiments and the prediction error of the peak value of F y can be controlled within 10 %. Moreover, multi-phase model is helpful for discovering the miscellaneous interactions of matrix, particle and tool and the induced complicated stress distribution in the cutting area, for further obtaining an in-depth understanding of removal mechanism of SiCp/Al6063 composites.

In the face milling of large low-rigidity aluminium alloy parts, the heat generated is one of the most important issues and leads to thermal expansion of the workpiece and the serious reduction of dimensional and geometrical precision. In this paper, a new heat transfer analytical model for face milling was established based on the heat source method, in which the cutting edge of the machine tool was considered as a finite-length rotating line heat source. Then, a transient numerical simulation was also conducted to predict the temperature field on the machined surface in single-tooth and multi-tooth milling by using the finite-element method (FEM). Finally, experiments involving the measurement of the aluminium alloy milling temperature were performed using a semi-artificial thermocouple, in which the hot end of the thermocouple was embedded into the machined surface to obtain the instantaneous face milling temperature. Those experimental results exhibited good agreement with the results from the theoretical analytical model and numerical simulation.

The surface quality of SiC particle-reinforced aluminum matrix (SiCp/Al) composite plays an important role in their practical performance. Therefore, an in-depth understanding of the defect formation mechanism paves the solid foundation for the improvement of machined surface quality, which is the prerequisite for the widespread application of SiCp/Al materials. In this paper, the geometrical analysis of milling process was conducted firstly. Then, two-dimensional meso-scale finite element models composed of hard SiC particles and soft aluminum matrix were established for investigating the milling process of the SiCp/Al composite. Both a randomly distributed circular SiC particles model and a polygon SiC particles model were built respectively with high volume fraction. The simulation result indicated that the rotation, pulling out, big cleavage, micro fracture, and cutting through of the SiC were the main defect formation mechanisms. The simulated machined surface morphology was compared with the profile of a milled surface, and a good correlation was obtained.

In this study, the grinding force variation mechanism in ultrasonic assisted grinding (UAG) of SiC ceramic is investigated by simulation method using a single diamond abrasive grain scratching. In simulation, the workpiece is modeled by smoothed particle hydrodynamic (SPH) method while the abrasive grain is modeled by finite element method (FEM). To reliably predict the grinding forces in UAG, an analytical model of average undeformed chip thickness ha is established. Grinding forces under different grinding parameters, i.e., depth of cut, and different ultrasonic vibration amplitudes are calculated by setting average undeformed chip thickness haas scratching depth during SPH simulation process. The simulation results indicate that the normal force in UAG is reduced by about 20%, while the tangential force decreases up to 30% compared with those in conventional grinding (CG). The influences of grinding parameters and ultrasonic vibration on grinding forces will be investigated and the preliminary explanations will be presented.

SiCp/Al composites (aluminum alloys reinforced with SiC particles) are classified as the typical difficult-to-machine materials by serious tool wear, premature tool failure, surface defects, etc. In order to understand the formation mechanism of chip and machined surface, the two-dimensional finite element modeling technology of the cutting process for SiCp/Al composites are investigated by using ABAQUS explicit. The actual microstructure is modeled by a multi-phase modeling approach with a circular SiC reinforcement phase randomly distributed in a 6061aluminum alloy matrix phase. The effect of volume fraction of SiC particles is studied by simulating the orthogonal cutting process of aluminum alloy and three SiCp/Al composites with multiplied increasing volume fraction of SiC reinforcement particles. The cutting forces vs. time due to the interaction between cutting tools and SiC particles in the cutting process and the stress distribution in three deformation zones are analyzed. Finally, surface defects including particles debonding, small pits, raised particles and traces of ploughing are predicted and verified by the experimental surface topography.

The aim of this paper is to compare the predicting ability of the orthogonal cutting models developed by three commonly used finite element softwares, namely commercial explicit dynamic code Abaqus/explicit, Thirdwave AdvantEdge and implicit finite element codes Deform 2D. In all proposed models, the chip formation was simulated through adaptive remeshing and plastic flow of work material around the round edge of the cutting tool. Therefore, there was no need for a chip separation criterion which made the physical process simulation more realistically. Predicted cutting, feed force and shear angle were compared with experimental results. In addition, the effect of friction coefficient on the chip morphology was investigated as well.

In recent years, micro-machining has obtained increasingly attention and been more and more widely used in the field of machining. As a vital important aspect in the design of micro-tool, traditional tool geometry design methods need to be improved. In this paper, the mathematical model of D-type micro end-mill is developed; FEM analysis using ABAQUS 6.12 is employed to optimize the geometry parameters of D-type micro end-mill, which is proved to be a very convenient method. For small diameter tools, strength is the primary factor to be considered in their design, so the target of optimization is to minimize the maximum principal stress and deformation of the micro-tools.

Now there is not engough basic theory to explain the friction mechanism on the shear deformation zone and tool-workpiece deformation zone in the process of metal cutting.But the constant coefficient of friction model is not in accord with the actual cutting tool friction. So Friction law of micro friction process were studied by friction test and simulation, the friction model of micro - cutting are very important which can improve the micro-cutting mechanism, finite element modeling and Simulation of metal cutting process and etc.

As the oil pressure of tank engine’s common-rail system is as high as 180MPa, it could bring a grate challenge to the oil con-rail’s seal quality. Especially in the condition of high oil pressure system, pulse load, metal creep deformation as well as machining error could low the reliability of con-rail’s. In tradition, shrinking the part’s tolerance is the main measure to ensure seal reliability .The measure eventually cause low efficiency, unnecessary waste, and high product cost in mechanical process. In this analysis, ABAQUS is exploited to discuss the influence that caused by various machining error on seal quality .Finally , the least taper angle error (critical point) lead to leakage is found. Besides the efficiency would be improved, the process cost also could be cut down a lot by using this data to constitute optimal technical files.

FEM is a powerful tool for predicting cutting process variables, which are difficult to obtain with experimental methods. In this paper modeling techniques on chip formation by using the commercial FEM code ABAQUS are discussed. Because of the limitations of Lagrangian and Eulerian methods, a modeling method based on ALE (Arbitrary Lagrangian Eulerian) technology is proposed to simulate the chip formation process. It consists of three chip formation analysis steps, i.e. initial chip formation, chip growth and steady-state chip formation. With this modeling method, high speed turning process of stainless steel 2Cr13 is simulated. And the predicted variables are compared with experimental data. It has been found that the results are in good agreement with the experimental ones.

By exploiting the polymer/silica hybrid and the air trench waveguide structures, we demonstrate a new type of low-power consuming and high-speed thermal-optic (TO) switch. Such a design provides an effective means to shorten the switching time of the TO switches, as well as to reduce the power consumption at the same time. This TO switch operated with less than 150 μs of switching time via a polymer/silica hybrid waveguide structure. Meanwhile, the power consumption was reduced to be 3.4 mW by introducing the air trench structure.

Stainless steel is a kind of difficult-to-cut materials because of its low heat conductance, poor machining quality, serious work hardening, built up edge and tool wear. In this paper, the mechanisms and varying law of tool wear vs. cutting parameters in turning stainless steels with carbide tools is first investigated by performing the systematical cutting experiments and examining with SEM instruments, and a mathematical model is derived which shows that the wear rate of the carbide tools is dependent on the cutting process variables at tool/chip and tool/work interface. In the prediction of these cutting process variables, FEM has advantages over experimental and analytical methods. Hence then the modelling techniques of chip formation process simulation by using the commercial FEM code ABAQUS are discussed. At last, a method to estimate the tool wear with the aid of FEM is proposed. With this method tool wear progress in turning operation is estimated. The predicted flank and crater wear are verified by experimental results. (5 pages)