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Simulation models of machine tool feed drive are utilized for process planning and optimization. In order to improve the estimation performance of such models, sophisticated parameter identification methods have been applied to capture the dynamic characteristics of feed drive precisely. However, the identification process, which comprises data gathering, data processing, and parameter estimation, is time-consuming and complex. Therefore, this paper presents a new rapid parameter identification algorithm based on the recursive least squares (RLS) method to identify feed drive mass and sliding friction. The proposed method simplifies the identification process by utilizing the measured data directly without data processing. A two-step identification technique is proposed for addressing the nonlinearity of the feed drive model, thus allowing for the application of the RLS method. The identification accuracy and fast convergence rate of the proposed algorithm were validated via simulations and experiments using a ball screw–driven feed drive testbed. The friction behavior and control characteristics estimated by the feed drive model were compared with experimental results to evaluate the estimation accuracy.

To deal with the compliance error that is structural deflection caused by an applied wrench in robotic applications, several compensation methods have been developed. However, conventional methods have limitations because they do not consider how compensation of one joint affects the compliance errors of the other joints. In this study, it is proposed that a joint compliance error compensation method that calculates the exact amount of compensation of each joint using a body frame. The effectiveness of the proposed method is evaluated using simulations.

The use of industrial robots is widespread in diverse manufacturing fields. Hence, there have been attempts to use robot for machining processes instead of machine tools. However, limited machining accuracy has been a major obstacle hampering the adoption of robotic machining systems. Recently, substantial research has been carried out to address this issue. In this paper, recent progress in robotic machining has been summarized, such as kinematic calibration and compliance error compensation to improve the accuracy of robotic machining. Auxiliary units for improving the performance of robotic machining systems are also discussed.

As product development cycles are getting shorter, faster determination of proper process conditions for the new designs and materials is increasingly important. To respond these requirements, a significant effort for cutting experiments are being replaced by simulation-based approaches called Virtual Machining (VM). Simultaneously, metal parts with thinner and smaller features being frequently used in electronic products has increased demands for precision machining of thin walls, which is vulnerable to post-machining deformation (PMD). In this study, a simulation procedure is discussed to incorporate the prediction of PMD after metal cutting into VM environments. The method uses a combination of the residual stress and thermal analysis of cutting process and the structural analysis of machined part. Machining experiments have been performed to demonstrate the effectiveness of the proposed PMD simulation as a part of VM for initial selection of the machining conditions.

Environmental monitoring has become essential in order to deal with environmental resources efficiently and safely in the realm of green technology. Environmental monitoring sensors are required for detection of environmental changes in industrial facilities under harsh conditions, (e.g. underground or subsea pipelines) in both the temporal and spatial domains. The utilization of optical fiber sensors is a promising scheme for environmental monitoring of this kind, owing to advantages including resistance to electromagnetic interference, durability under extreme temperatures and pressures, high transmission rate, light weight, small size, and flexibility. In this paper, the optical fiber sensors employed in environmental monitoring are summarized for understanding of their sensing principles and fabrication processes. Numerous specific applications in petroleum engineering, civil engineering, and agricultural engineering are explored, followed by discussion on the potentials of OFS in manufacturing.

Polydimethylsiloxane (PDMS) is widely used in the fabrication of fluidic chips. Recently, a direct mechanical micromilling process using cryogenic cooling was considered to cut PDMS in order to reduce development time and prototyping costs. In this paper, the characteristics of cryogenic machining of PDMS were experimentally studied. The machined surface was analyzed with a variety of machining parameters, such as spindle speed and feed per tooth, and their effects on cutting temperature were examined. To improve geometric accuracy, a tool path compensation method that takes into account the shrinkage of PDMS at cryogenic temperatures was developed. Based on the preliminary results, the fabrication of a PDMS fluidic chip demonstrated that fluidic flow can be controlled by differences in the flow friction.

Cast iron is relatively cheap and highly machinable and is thus used for various mechanical parts. However, cast iron (H2 grade) is a high-carbon steel that shows cracks or craters owing to the martensitic transformation during conventional surface heat treatments. In this study, we investigated electron-beam (e-beam)-based direct preheating for preventing the formation of craters and cracks during the heat treatment of cast iron using a plasma diode e-beam. Scanning electron microscopy, X-ray diffraction analysis, energy-dispersive X-ray spectroscopy, and hardness measurements were performed to elucidate the crater and crack formation mechanism. Craters were formed within the graphite phase, owing to the low-melting-point elements and compounds. It was also observed that crack and crater formation was correlated to the distortion of the primary gamma phase, based on a significant decrease in the d-spacings. The direct preheating process resulted in a lower degree of distortion of the gamma phase. As a result, we could achieve a hardness as high as 800 HV without cracks or craters in cast iron, which is a cheap material. Moreover, the results of potentiodynamic polarization tests showed that the corrosion resistance increased after the surface treatment, owing to the removal of the low-melting-point impurities and grain refinement.

This paper presents a real-time tool deflection compensation technique to improve micromilling machining accuracy. Lateral and axial errors of the cutter location (CL) caused by tool deflection were estimated using the cutting force and compensated by applying an additional feed to the workpiece that is equivalent to the estimated CL errors. To evaluate the proposed method, a workpiece holder comprising a three-axis stage and a tool dynamometer was installed on the work table of a machine tool. A proportional derivative (PD) position controller with a model-based tool deflection estimator was designed and implemented on a real-time computer to control the workpiece holder. Lateral and axial machining errors in side milling and radii errors in circular slot milling are discussed to demonstrate the effect of tool deflection compensation.

Magnetorheological (MR) fluid jet polishing is a material removal process for precision products such as optical elements. It is characterized by a jet flow that is stabilized by a magnetic field, and a highly predictable machining spot. The behavior of the particles in an MR fluid slurry near a target wall surface is conceptually described. In experiments with a BK7 glass specimen, various removal spots are created by impingement of MR fluid jets at velocities of 10~30 m/s, using MR fluids of different compositions, and different processing durations. The tangential MR fluid flow along the part surface is assumed to be responsible for material removal, and theoretical models for the prediction of material removal are developed, using the conventional wear model and granular flow theory. The constitutive relation between the shear stress and the shear rate changes as the jet velocity increases, which has a critical effect on the behavior of material removal. CFD analysis is performed to calculate the wall shear rate. The proposed models agree with the experimental results with respect to the distribution of the material removal rate. Additionally, the surface topographies of polished parts are discussed, with regards to the particle behavior.

Glassy carbon (GC) has merits to be used as mold material for glass molding press because of its superior chemical and thermal properties. However, it is difficult to machine GC mechanically because of its brittleness and hardness. Undesired fractures and cracks are frequently generated on the machined surfaces. A novel micromachining process for precision machining of GC that combines mechanical micromachining and electrochemical oxidation has been developed. In the proposed process, an oxide layer is generated on the GC surface and removed mechanically. In the contact area between the tool and workpiece, the generation and removal of the oxide layer are repeated. A number of experimental results are presented to investigate the machining characteristics and to show the feasibility of the proposed process.

Electron beam cathodes have been used in various fields such as microscopy, X-ray tubes, welding, and surface modification. Generally, cathodes use metals with lower work function, higher thermal resistance, lower poisoning effects of gases, etc. LaB6, tungsten, and tantalum have normally been used as cathode materials with special materials coated if required. This study investigated the high-voltage plasma diode cathode for surface modifications of metal products such as polishing, hardening and heat treatment. The most fascinating features of this cathode are the high voltage and current that can be obtained at a low vacuum of a few mTorr. However, it is difficult to control the emission current to attain a steady state and to obtain higher brightness than that achieved using a thermal cathode. We studied the emission characteristics in terms of cathode and anode design parameters such as anode distance and cathode shape. Additionally, changes of emission characteristics are discussed in terms of the type of gas, pressure parameter, etc. using the emission resistance, effective breakdown voltage, and brightness. Finally, by measuring the change in surface roughness using the emitted electron beams, we found that the surface roughness values before the process were Ra=0.8 µm and Rz=5.4 µm, whereas those after the process were Ra=0.25 µm and Rz=2.3 µm. The electron beam polishing technology is eco-friendly and can minimize the emission of many harmful materials that arise when existing mechanical or electrochemical polishing technologies are used.

Microinjection moulding of high-aspect-ratio microstructures is important for the fabrication of various microsystem components. Successful microinjection moulding technologies may depend on accurate understanding of the cavity filling process of a polymer melt and a reasonable prediction of the filling degree in a microchannel. To date, there has been a lack of adequate investigations of the filling process in injection moulding for microcantilever structures. In this study, the microinjection moulding of microcantilevers was performed with dynamic mould temperature control and cavity pressure measurement. The influences of injection flow rate, peak cavity pressure, melt temperature, and mould temperature on the filling length were observed. A simple, one-dimensional analytical model was developed that describes the relationship of the four process parameters with the filling length. The measured cavity pressure profiles were applied to the numerical analyses. The model was validated by comparison with both experimental measurements and simulation results and showed acceptable agreement among the processing parameters. The development of the cavity pressure and the temperature transition of the melt in the microchannels had a critical influence on the filling process. The increase in the mould temperature over the glass transition temperature during a filling stage using the mould temperature control system was the most effective way to maximize the filling length. The combination of the theoretical model and cavity pressure measurements can be used to predict the filling length and design the injection mould for high-aspect-ratio microstructures.

This paper describes a virtual machine tool (VMT) that can be used to estimate the energy consumption of machine tools at the component level. The VMT was designed by focusing on accurately estimating the dynamic behavior and energy consumption of the servo system, which has a major impact on the total energy consumption. Simulation models of the controller and feed drive were constructed. The energy consumption levels of the feed drive components were analyzed theoretically and integrated into the model. An experimental setup of the servo system incorporating a hardware-in-the-loop simulation testbed was constructed to evaluate the proposed model. Simplified models of the spindle, auxiliary units, and cutting dynamics were included in the VMT to estimate the energy consumption of the machine tool components during milling. This simulation technique was used to quantify the effects of machine tool design modification and process control and to simulate the relationship between the specific energy consumption and the material removal rate in order to reduce the overall energy consumption.

Electrical discharge machining (EDM) is a process that can be used effectively to machine conductive metals regardless of their hardness. In the EDM process, material removal occurs because of the thermal energy of the plasma channel between the electrode and the workpiece. During EDM, the electrode as well as the workpiece is abraded by the thermal energy. Tool wear adversely affects the machining accuracy and increases tooling costs. Many previous studies have focused on mitigating the problems of tool wear by investigating various EDM parameters. In this study, the tool wear problem was investigated on the basis of the mobilities of electrons and ions in the plasma channel. The material removal volumes of both the electrode and the workpiece were compared as functions of the gap voltage. The material removal difference according to the capacitance was also investigated. The tool wear ratio was calculated under different EDM condition and an EDM conditions for reducing the tool wear ratio was suggested.

In recent times, simulation techniques have been rapidly accepted by the machine tool industry. However, most existing simulation studies have focused on a particular machine tool and described an entire machine tool feed drive as a single combined system. This paper presents a method to accurately predict motor current (torque) behavior and acquire a more generalized and accurate dynamic simulation model for a machine tool feed drive. To improve the generality, a component-based approach is introduced. In this approach, the feed drive model is composed of subcomponent models, and each component mechanism is then independently modeled. In the developed model structure, the parameters of the subcomponent model can easily be determined by using product datasheets or simple parameter identification based on motor current measurements. To enhance the model accuracy in predicting the motor current, an improved friction model including time-dependent frictional characteristics and rolling contact conditions was introduced to the simulation. The performance of the developed dynamic simulation model is demonstrated through a comparison with real machine tool behavior.

Research on the improvement of efficiency in the manufacturing industry is underdeveloped partly because of the ambiguous objectives of the technical development of efficiencies in terms of energy consumption reduction. Consequently, the technical development of high-efficiency techniques that consider the whole manufacturing system is rarely addressed in industrial research. For this reason, this report aims to find the patterns in, and the definitions of, the technologies that will lead to efficiency improvement in the entire manufacturing industry by thoroughly investigating the literature about energy consumption reduction strategies, energy policies, and the state-of-the-art for energy-saving methods that are being pursued currently in several major countries. Through this study, the necessity and importance of the foregoing three items have been identified, and a way of defining the productivities of an energy-saving manufacturing system distinct from those of conventional manufacturing systems was attempted. It is also shown that the development of energy-saving and energy-harvesting technologies for all industrial sectors has emerged as a herald of economic growth in the near future.

Magnetorheological (MR) fluid is used as the working medium in MR finishing. The viscosity of the MR fluid, which determines the shear acting on the workpiece surface stress, can be controlled by the intensity of the applied external magnetic field, and is thus an important design parameter in the finishing process. Most previous studies have used a shear stress value obtained experimentally under a limited set of conditions. Although a recent theoretical model that predicts the shear stress in an external vertical magnetic field has been developed, it treats the energy variation with respect to the strain and the intensity of the magnetic field only among the adjoining particles in a chain. Because that model assumes no multiparticle interactions, it is not well suited to a case in which the magnetic field is more than one dimension such as in MR finishing. In this study, a new three-dimensional model is proposed by expanding the one-dimensional model and considering multiparticle interactions. The proposed model assumes that each particle is surrounded by the 26 neighboring particles, and the total internal energy is estimated by calculating the magnetic dipole interactions among the particles. Therefore, the proposed model considers not only the particle-to-particle energy variations, but also the chain-to-chain energy variations. The behavior of MR fluid is evaluated using the proposed model in a two-dimensional skewed magnetic field.

A volumetric error compensation method for a ma- chining center that has multiple cutting tools operating simul- taneously has been developed. Due to axis sharing, the geo- metric errors of multi-spindle, concurrent cutting processes are characterized by a significant coupling of error components in each cutting tool. As a result, it is not possible to achieve ex- act volumetric error compensation for all axes. To minimize the overall volumetric error in simultaneous cutting, a method to determine compensation amount using weighted least squares has been proposed. This method also allows tolerance distribu- tion of machining accuracy for different surfaces of a workpiece. A geometric error model has been developed using an arch-type, multi-spindle machine tool, and the error compensation simula- tion results based on this model are presented. The simulation results demonstrated effectiveness of the proposed error compen- sation algorithm for use with multi-spindle simultaneous cutting applications.

There is an ever-growing demand for high precision machining to obtain increased accuracy and surface finish, as they are key factors in product quality and performance. Machining operations, in general, are associated with errors of varying magnitude originating from different sources. As a result, the sizes of the machined features usually deviate from their desired, nominal values. Identification of error sources, techniques of measurements (on/off line), and efficient strategies for their compensation are the steps required to minimize, and, in some cases eliminate process errors. This paper focuses on modeling and compensation of geometric errors in machining operations specific to the line boring process. It is part of an undergoing research project focused on design and development of an agile precision line boring station for machining of long bores. After a brief overview of sources of geometric errors and their components, a methodology for their calculation is introduced. In this regard, error equations reflecting the effects of machine tool geometric errors at the tool tip are derived. It is shown that these equations can be further simplified without significantly affecting computational accuracy of the results. This makes the approach more attractive for real-time applications. A set of experimental data obtained from a prototype of the machine is used to study the effectiveness of the proposed approach and the results are reported. The paper concludes with discussions and presentation of different methods and available tools for real time compensation of these errors.