The manufacturing industry faces two significant challenges: declining added value due to industrial restructuring and an aging workforce stemming from demographic shifts. In the machining sector, leveraging big data from machine tools has become increasingly critical for enhancing productivity and implementing intelligent manufacturing systems. However, varying data formats and communication methods across different equipment hinder efficient integration, posing a major barrier to the digital transformation of manufacturing. This study develops an integrated server system to facilitate the digital transformation of the machining industry by enabling effective collection, storage, processing, and analysis of data from machine tools. The system features a standardized protocol-based interface for consistent data collection and control across heterogeneous CNC machine tools. By leveraging IEC 62541 OPC UA (Open Platform Communication Unified Architecture) and OPC 40501-1 UMATI (Universal Machine Technology Interface), it ensures interoperability with upper-level applications through standardized information models. The proposed approach addresses inefficiencies in vendor-dependent CNC data systems, providing consistent data management for diverse equipment. By enhancing real-time data handling and eliminating integration challenges, the system contributes to the digital transformation of the manufacturing sector and the creation of an efficient production environment.
As the global manufacturing industry moves toward carbon neutrality, improving energy efficiency of machine tools has become essential. Although machine tools contribute significantly to industrial energy consumption, systematic methods for evaluating their energy consumption remain insufficient. To address this issue, this study developed an energy consumption evaluation system based on ISO 14955, the international standard for machine tool energy efficiency. The proposed system enabled a detailed analysis of energy usage patterns in different operating states, identifying key areas for energy reduction. The developed system could measure energy consumption of individual machine tool components in various operating states using power meters and automatically generates reports. This allows users to identify which components and operating states consume the most energy. We tested and validated this system on three different machine tools and analyzed strategies for reducing energy consumption. The developed evaluation system can help machine tool manufacturers integrate it into their equipment, develop energy-efficient technologies, and contribute to sustainable manufacturing.
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Recent Advances in CNC Technology: Toward Autonomous and Sustainable Manufacturing Jong-Min Lim, Wontaek Song, Joon-Soo Lee, Ji-Myeong Park, Hee-Min Shin, In-Wook Oh, Soon-Hong Hwang, Seungmin Jeong, Sangwon Kang, Chan-Young Lee, Byung-Kwon Min International Journal of Precision Engineering and Manufacturing.2025; 26(9): 2311. CrossRef
The importance of cutting forces in machining has been emphasized for monitoring and optimizing cutting conditions, leading to various method to detecting cutting forces researched. Cutting forces can be directly measured using dynamometer or indirectly estimated using AE sensors and accelerometers, etc. However, these external sensors demand high costs and have accuracy limitations due to environment issues. To compensate for these drawbacks, utilizing internal signals of machine tool has been developed. Among these, using internal electrical signals of machine tool is representative. In commercial machine tools, cutting forces are often estimated through current measurements. However, due to the characteristics of the spindle motor, electrical properties such as slip, power factor, and efficiency vary with the load, resulting in relatively lower accuracy. This study introduces current-based method considering characteristics of motor and power-based method for estimating cutting forces and compare accuracy of those methods with the measurements from dynamometer respectively.
In order to monitor the machining status of a machine tool, it is necessary to measure the signal of the machine tool and establish the relationship between the machining status and the signal. One effective approach is to utilize an AIbased analysis model. To improve the accuracy and reliability of AI models, it is crucial to identify the features of the model through signal analysis. However, when dealing with time series data, it has been challenging to identify these features. Therefore, instead of directly applying time series data, a method was used to extract the best features by processing the data using techniques such as RMS and FFT. Recently, there have been numerous reported cases of designing AI models with high accuracy and reliability by directly applying time series data to find the best features, particularly in the case of AI models combining CNN and LSTM. In this paper, time series data obtained through a gap sensor are directly applied to an AI model that combines CNN, LSTM, and MLP (Multi-Layer Perceptron) to determine tool wear. The machine tool and tool status were monitored and evaluated through an AI model trained using time series data from the machining process.
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Development of AI-based Bearing Machining Process Defect Monitoring System Dae-Youn Kim, Dongwoo Go, Seunghoon Lee Journal of Society of Korea Industrial and Systems Engineering.2025; 48(3): 112. CrossRef
A Review of Intelligent Machining Process in CNC Machine Tool Systems Joo Sung Yoon, Il-ha Park, Dong Yoon Lee International Journal of Precision Engineering and Manufacturing.2025; 26(9): 2243. CrossRef
Work coordinate setup is a time-consuming and difficult task in ultraprecision machining. The setup process determines the precision and tolerance of the machined parts. In ultraprecision machining, the table can be moved in the nanometer range, but the accuracy of the measuring device has not reached the nanometer accuracy range. Although several measurement methods have been proposed, the attained precision is still insufficient. Some methods also lose the precision when the sensor is changed with the tool after the work coordinate setup is completed. A work coordinate setup method proposed in this study could improve the precision and the measurement process using electron tunneling. Since the method can use the tool as a sensor probe, the changing process does not degrade the measurement precision. In addition, the proposed method can theoretically detect the distance between the tool and the workpiece in sub-nanometers like a scanning tunneling microscope. The simple system requires a precision current amplifier capable of measuring electron tunneling current in the picoampere to nanoampere range and a power supply. The method, installed on an ultra-precision machine tool, was tested on WC and aluminum material. The accuracy of the method was evaluated for applied voltage.
In general, rotor inertia has an inversely proportional relationship with proportional gain and bandwidth in a turret speed control system of machine tools; thus, this system has a disadvantage, such as weak disturbance caused by a decrease in the damping ratio and an increase in bandwidth due to low rotor inertia. This paper proposes a damping compensator that is resistance to disturbances in order to improve the above problems. The proposed damping compensator reduces the residual vibration induced in the transient state by using a digital high-pass filter. The experimental results showed that the overshoot was reduced by about 5.5% in the speed response and by about 20% in the torque response in the no-load condition. Under the load condition of 4.8 N.m, the torque response showed that the undershoot was reduced by about 26%.
Estimation and compensation of geometric errors for rotary axes are among methods to improve machining accuracy of five-axis machine tools. Studies have been conducted on various methodologies for estimating geometric errors for rotary axes, which are essential for improving machining accuracies of five-axis CNC machine tools. This paper presents a method for estimating geometric errors of a rotating/tilting table using a cross-shaped calibration artifact with a touch trigger probe. The proposed method includes rotary axes error estimation equations for angles of each rotary and tilt axis based on locations of probing points. Computer simulations were performed based on a MATLAB/Simulink and ADAMS cosimulation system using the probing cycle process to verify the proposed method. Computer simulation results confirmed the usefulness of the proposed method in terms of volumetric errors.
A virtual machine tool, a computer simulation model of the machine motion and cutting process with a level of accuracy and consistency that can replace an accurate machine tool, is one of the critical digital transformation technologies in the manufacturing industry. During the machine development phase, cost and time can be reduced by evaluating machining efficiency and quality through virtual prototyping. In the machine application phase, virtual machine tools can be used to accurately assess the condition of equipment and processes by analyzing actual data combined with simulated data. This paper introduces a virtual machine tool system that can analyze the behavior of an accurate machine tool by integrating physical models of structure, numerical controller, and cutting process. The key features of the virtual machine tool, synchronous machining simulation, machining stability detection, machining error estimation, and part program optimization, were evaluated through various machining tests with a vertical 3-axis milling machine.
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A Review of Intelligent Machining Process in CNC Machine Tool Systems Joo Sung Yoon, Il-ha Park, Dong Yoon Lee International Journal of Precision Engineering and Manufacturing.2025; 26(9): 2243. CrossRef
In the existing machine tool field, the focus was on the displacement of the feed system from the viewpoint of the motion of the machine tool. The displacement of the tool or spindle of a machine tool is useful for developing various functions. In this study, using the acceleration data of the spindle, we proposed an algorithm that tracked the displacement of the spindle with respect to the pseudo-step waveform motion. In order to solve the bandwidth problem of the pseudo-step waveform, the displacement data measured by the motor encoder of the feed system was used. In addition, in order to solve the drift problem due to double integration, a new drift removal filter was proposed and a displacement estimation algorithm was implemented. In order to examine the performance and possibility of the proposed spindle displacement estimation algorithm, it was applied to a gantry-type engraver and its excellent performance was confirmed compared to other algorithms.
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A Review of Intelligent Machining Process in CNC Machine Tool Systems Joo Sung Yoon, Il-ha Park, Dong Yoon Lee International Journal of Precision Engineering and Manufacturing.2025; 26(9): 2243. CrossRef
This paper describes the design of a 4-axis SCARA-Type robot in the form of a scalar robot for the loading and unloading of workpieces in machine tools. The 4-axis dedicated robot is a 4-degrees-of-freedom robot consisting of a joint 1, 2, 3 motor and a 180° rotating gripper made up of a horizontal gripper and a vertical gripper. It was designed in a scalar shape that is suitable for machine tools, and the size of each link and elbow was determined through structural analysis. Through additional structural analysis, the deflection of the end center of the workpiece fixed to the horizontal gripper and the vertical gripper was designed to be within 0.1 mm, and based on the design result, a 4-axis SCARA-Type robot was manufactured, and the basic motion characteristics of the manufactured robot were tested. As a result of the characteristic test, the manufactured 4-axis SCARA-Type robot operated smoothly, so it is judged to be adequate for usage in loading and unloading the workpieces in machine tools.
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Design and develop a robot arm to automatically feed workpieces for laser engraving machines Trung Xuan, Duy Anh FME Transactions.2024; 52(4): 671. CrossRef
5-Axis Robot Design for Loading and Unloading Workpieces Han-Sol Kim, Gab-Soon Kim International Journal of Precision Engineering and Manufacturing.2023; 24(12): 2279. CrossRef
ISO 10791-6 specifies test conditions, BK1 and BK2, including circularly interpolated motions by simultaneous control of two linear axes and a rotary/tilting axis, for five-axis machine tools with a tilting-rotary table. Eccentricities of measured motions are used to identify position-independent geometric errors of the rotary/tilting axis. However, time-consuming alignments of measurement devices are required to execute the circular motions due to large geometric errors of the tilting axis. In this paper, a simple method is proposed to align an initial position of a tool-center-point (TCP) relative to the actual tilting axis of five-axis machine tools for application of ISO 10791-6. A ball at the tool nose with an extension fixture, supplied commercially by a double ball-bar manufacturer, is used to measure positional deviations of a ball on workpiece table at 90° command angle of a tilting axis. An alignment error of a TCP is identified simply by using a geometric relationship of the TCP and measured deviations. Then, identified alignment errors are used to calculate initial position of a TCP for fine measurements of position-independent geometric errors specified in ISO 10791-6. The proposed method is applied to a five-axis machine tool and verified experimentally.
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A Study on the Estimation of Geometric Errors for Rotary Axes of a Five-Axis Machine Tool Using a Cross-Shaped Calibration Artifact Jeongmo Kang, Dayoung Kim, Sungchul Jee Journal of the Korean Society for Precision Engineering.2023; 40(1): 87. CrossRef
A TCP Calibration of a 6-Axis Manipulator and Geometric Errors Identification of a Tilting-Rotary Table Kwang-Il Lee, Do-Hun Kim, Hoon-Hee Lee, Seung-Han Yang Journal of the Korean Society for Precision Engineering.2022; 39(4): 253. CrossRef
We propose the measurement method for location errors in a horizontal 4-axis machine tool using a touch trigger probe and a sphere artifact. Location errors (type of geometric errors), are values that do not change with the position of each feed axis because these errors are usually fixed in an assembly procedure. There are seven location errors in a horizontal 4-axis machine tool; three squareness errors in three linear axes and two squareness and two offset errors in a rotary axis. The positions of center point of sphere artifact on a rotary axis are measured by a touch trigger probe mounted on a tool axis. Because measured center points are expressed by seven location errors via the homogeneous transformation matrix, location errors can be separated by analyzing measured data. To validate the proposed method, measurement experiments were performed on a horizontal 4-axis machine tool. Measurement results were verified by comparing before and after compensation.
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Sequential Measurement of Position-independent Geometric Errors in the Rotary and Spindle Axes of a Hybrid Parallel Kinematic Machine Seung-Han Yang, Dong-Mok Lee, Hoon-Hee Lee, Kwang-Il Lee International Journal of Precision Engineering and Manufacturing.2020; 21(12): 2391. CrossRef
Transportation industries, such as aerospace and automotive demand high efficiency using lightweight parts. Carbon Fiber Reinforced Plastics (CFRP) present promising materials for transportation industry parts due to their lightweight and highstrength properties. Forming and machining processes are required to manufacture parts from carbon fiber composite materials. The near-net shaping process forms the parts, and the final accurate shape and hole are accomplished using the machining process. However, high-strength carbon fiber chips and dust from the machining process cause cutting tool wear and low productivity. The hybrid CRD (Cutting, Routing and Drilling)/water-jet machine improves tool life and productivity because its water-jet process, employed before the mechanical machining process cuts roughly without chips and dust. In this study, the hybrid CRD/water-jet machine we developed was introduced and its machining performance was evaluated using a drilling process. The delamination factor and surface roughness of drilled holes were compared with the results from a conventional machine tool.
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Effect of Vacuum Suction on Dust and Exit Burr Removal in FRP Drilling Jong-Hyun Baek, Su-Jin Kim Journal of the Korean Society of Manufacturing Process Engineers.2022; 21(11): 29. CrossRef
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In the manufacture of mechanical components, volumetric errors of a machine tool should be checked and reduced to meet the required tolerance levels. In this paper, we propose a quick and simple method of measurement for checking and compensating geometric errors which include scaling and squareness errors. During the measurement, which usually takes approximately 5 minutes to complete, the machine tool is first commanded into four vertices sequentially on a virtual regular tetrahedron. Subsequently, the six lengths between four vertices are measured using a double ball-bar and geometric errors are calculated from the measured lengths. In order to verify the measurement result, the measured geometric errors are compensated using NC-code and the six lengths are re-measured to confirm the error correction. In conclusion, a double ball-bar circular test on XY-, YZ-, ZX-plane is done, first without compensation and then with the compensation of the measured geometric errors to check the effect of compensation practically.
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Use of a Virtual Polyhedron for Interim Checking of the Volumetric and Geometric Errors of Machine Tools Kwang-Il Lee, Heung-Ki Jeon, Jae-Chang Lee, Seung-Han Yang International Journal of Precision Engineering and Manufacturing.2022; 23(10): 1133. CrossRef
Measurement of Location Errors in a Horizontal 4-axis Machine Tool using a Touch Trigger Probe Ji Hun Jeong, Gyungho Khim, Jeong Seok Oh, Sung-Chong Chung Journal of the Korean Society for Precision Engineering.2019; 36(8): 745. CrossRef
Various types of 5-axis machine tools have been developed. In the case of a machine tool composed from linear motion, the kinematic equation can be obtained easily and intuitively. However, machine tools with more than four axes, including rotating axes, have generally performed kinematic and dynamic performance analyses using mathematical methods. In this paper, the kinematic equations of various types of machine tools are obtained, based on the Homogeneous Transformation Matrix method. The loop stiffness was then calculated as a mathematical model. A mathematical model of loop stiffness was verified by using a method to calculate the loop stiffness of a commercial program. The results of the mathematical model showed less than a 1% error with the commercial program, and this could show the validity of the mathematical model. Then, this model was applied to two types of machine tools. The minimum loop stiffness of both models is compared.
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Research and development of multi-axis CNC abrasive belt-grinding machine postprocessor Hu Qiao, Zhenxing Wei, Ruixiang Deng, Tianhang Xu, Ying Xiang The International Journal of Advanced Manufacturing Technology.2023; 126(7-8): 3109. CrossRef
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