Computer Numerical Control Research Articles

Multi-Objective Cutting Parameter Optimization Method for the Energy Consumption and Machining Quality of Computerized Numerical Control Lathes

In order to achieve minimum energy consumption in computerized numerical control (CNC) lathe processing under the premise of ensuring the imposed roughness of the machined surface, a black hole-continuous ant colony optimization algorithm (BH-ACOR) is proposed to optimize the turning parameters. Taking turning specific energy and surface roughness as the optimization objectives, a turning test was designed. Subsequently, a multi-objective mathematical model of the cutting stage was formulated through the application of the least-squares method to fit the test data. The black hole algorithm was introduced to mitigate the shortcomings of the continuous-domain ant colony algorithm, which easily falls into a local optimum, so as to put forward a kind of BH-ACOR that is applicable to multi-objective optimization. The algorithm was applied to the multi-objective mathematical model in the turning stage to determine the optimal cutting parameters. Through simulation and test verification, the validity and practicability of the proposed method are further proved.

Analysis of Work Readiness Research Instruments for Vocational High School of the Mechanical Engineering Program

Objective: One of the levels of education in Indonesia is Vocational High School (VHS). VHS provides various skills programs, and VHS’s graduates should have greater opportunities to work based on their competencies. However, in East Java, most of the unemployed are VHS graduates. One of the skills programs at VHS is the Mechanical Engineering Skills program. The research purpose was to analyze the instrument research of work readiness vocational high school of the Mechanical Engineering program. Method: This research used a quantitative method. Instrument Work Readiness (WR) with variable problem-solving skills (PSS), Technology Skills (TS), Teamwork Skills (TWS) and Self-management Skills (SMS). Validity test of instrument used software Winstep Rasch analysis and reliability test of instrument used software Stata. The instrument, which has been validated by experts, was tested on 30 respondents. Results: aspect validity about test quality, model of legibility, and instrument sheet. Instrument validity of PSS was advisability 91.3%, CVR 0.92 and reliability 0.797, TS was advisability 93.6%, CVR 0.95 and reliability 0.491, TWS was advisability 90.3%, CVR 0.87 and reliability 0.798, SMS was advisability 92.6%, CVR 0.86 and reliability 0.941, WR advisability 95%, CVR 0.95 and reliability 0.946. Novelty: New model research instrument for measuring problem-solving skills, technology skills, teamwork skills, and self-management skills on the work readiness of students at Machining Engineering Vocational High School in East Java together. Machining engineering specially measured Computer Numerically Controlled (CNC) competence likely design workpiece, CNC programming, programming simulation, and inputting CNC programming.

Stereolithography-manufactured zirconia substrate with bionic-patterned surface microstructure for enhancing bond strength to porcelain veneer

The bond strength between the zirconia substrates and porcelain materials has been extensively investigated, and sandblasting is one of the most effective methods for increasing the bond strength between zirconia and porcelain. However, it also introduces microcracks and pollution, which have a negative impact on the final mechanical properties of zirconia restorations. To increase the mechanical chimaerism of zirconia/veneer structures nondestructively, in this study we developed a novel surface design called a bionic-patterned surface microstructure (BSM) using stereolithography (SLA) technology. Inspired by the dentin–enamel junction model, the microstructure includes a cylinder and pit. Among all the specimens, both computer numerical control (CNC) zirconia with sandblasting and SLA zirconia with BSM showed higher bond strengths than the CNC group (P < 0.001), and the BSM groups showed improved bonding properties (P < 0.001). No significant differences were observed between the cylindrical and pit BSM at the same height/depth (P = 0.493), and for BSM of the same type, the bond strength increased with increasing height/depth (P < 0.001). Zirconia with BSM thus had superior bond strength to porcelain veneers. The height/depth of the BSM had a positive effect on the bonding strength, whereas the type had no effect.

A Laboratory-Based Multidisciplinary Approach for Effective Education and Training in Industrial Collaborative Robotics

The rapid evolution of robotics across various sectors, including healthcare, manufacturing, and domestic applications, has underscored a significant workforce skills gap. The shortage of qualified professionals in the labor market has had adverse effects on production capacities. Therefore, the significance of education and training for cultivating a skilled workforce cannot be overstated. This research work presents the development of a pedagogical approach centered on laboratory infrastructure designed specifically with multidisciplinary technologies and strategic human–machine interaction protocols to enhance learning in industrial robotics courses. Progressive competencies in laboratory protocols are developed, focusing on programming and simulating real-world industrial robotics tasks, to bridge the gap between theoretical education and practical industrial applications for higher education students. The proposed infrastructure includes a user-configurable maze comprising different colored elements, defining starting points, endpoints, obstacles, and varying track sections. These elements foster a dynamic and unpredictable learning environment. The infrastructure is fabricated using Computer Numerical Control (CNC) machining and 3D printing techniques. A collaborative robot, the Universal Robots UR3e, is used to navigate the maze and solve the track with advanced computer vision and human–machine communication. The amalgamation of practical experience and collaborative robotics furnishes students with hands-on experience, equipping them with the requisite skills for effective programming and manipulation of robotic devices. Empowering human–machine interaction and human–robot collaboration assists in addressing the industry’s demand for skilled labor in operating collaborative robotic manipulators.

РАЗРАБОТКА ПРОГРАММНОГО ОБЕСПЕЧЕНИЯ ДЛЯ СИСТЕМ АВТОМАТИЗИРОВАННОГО УПРАВЛЕНИЯ ТЕХНОЛОГИЧЕСКИМ ПРОЦЕССОМ МЕХАНООБРАБОТКИ

The automation of production processes is the main direction in which manufacturing is currently being taken around the world. Currently, production automation is one of the ways to increase the efficiency of an enterprise. The main direction of automation of machining production is based on the widespread introduction of computer numerical control (CNC) systems. In a situation of limited opportunities to purchase new equipment with numerical control, the task of import substitution is set. One of the directions in solving this issue is expanding the functionality of existing CNC equipment at the enterprise by developing new control programs for them. This paper presents the results obtained for the milling section of numerically controlled machines of the HAAS model of the Super Mini Mill series of the industrial enterprise Avia LLC. The fundamental feature of a CNC machine is that it works according to a control program (CP), on which the cycle of operation of the equipment for processing a specific part is recorded. A preliminary analysis of the technical documentation of these machines showed that a number of important operations are missing from the control program, as a result of which some of them are performed manually by operators. The authors have developed new software, taking into account the identified shortcomings, using additional operations that expand the functionality of the considered equipment and eliminate manual control by machine operators. The software in automatic mode provides: setting a correction for the tool radius, which allows you to make the part contour programmed in the NC program independent of the diameter of the tool used; control of turning on/off the cutting fluid (coolant); the function of turning on the optional stop of the machine, in which the next operation starts automatically; recording the time of operations at each section of product processing. The program allows you to automatically control the trajectory of movement of the machine's executive bodies, and automates the process at the stage of setting up the tool for the product processing technology. Thus, automation of a number of operations on a CNC machine is aimed at increasing productivity, quality and accuracy of processing, reducing processing time and reducing the risk of producing defective parts. Author's certificates for state registration of the computer program were received.

Istraživanje proizvodnje malog stepenastog rotorskog točka postupkom graviranja

This study aims to explore the potential of the engraving milling process to manufacture 3D structures and layouts like rotor wheels. An experimental study was carried out to manufacture a stepped rotor wheel from EN8 steel blank using a computer numeric control (CNC) engraving milling machine tool. The impact of variable parameters, namely rotational speed (SR), feed (f), and plunge feed (Pf), on maximum roughness depth (Rt) and material removal rate (MRR) was determined through a total of fourteen tests, each with two replications based on Box-Behnken design (BBD) of the response surface methodology (RSM). The best variable combination was found using desirability functional analysis (DFA) with goals of minimizing Rt and maximizing the MRR. The best values achieved at the optimal combination of variable parameters were 2.95 µm as Rt and 43.45 mm³/min as MRR. Micrographs of the rotor wheel blades and cutting tool supported the findings.

Smoothing interpolation of five-axis tool path with less feedrate fluctuation and higher computation efficiency

Five-axis machine tools are widely used in aerospace, die and mold industries. Most of the time, the tool path is described by connecting a series of short linear segments. The tangency discontinuity of the linear segments leads to the discontinuity of the kinematic profiles, hence generating discontinuous interpolation points, and resulting in fluctuation of machine motion, which reduces the machining efficiency and causes excessive tracking and contouring errors. This paper aims to generate smooth interpolation points at servo sample intervals with the proposed G2 continuous five-axis corner rounding algorithm suitable for reducing feedrate fluctuation along the smoothed toolpath and improving machining efficiency, and the modified jerk-limited feedrate planning algorithm suitable for eliminating feedrate fluctuation within the feedrate planning units and improving interpolation computation efficiency. In this paper, the five-axis linear segments are first smoothed by curvature-optimized cubic Bezier splines, which reduces the number of the feedrate planning units along the smoothed toolpath and improves machining efficiency. Then, the jerk-limited feedrate planning algorithm is modified to ensure that the time interval of each different scheduled feedrate phase is an integer multiple of the axis position control loop closure time (i.e. servo sample interval), which eliminates the feedrate fluctuation within each feedrate planning unit and reduces the interpolation computation load of position command in each interpolation period (i.e. servo sample interval). At last, the effectiveness of the proposed algorithm is demonstrated with simulations and experiments following a five-axis, curved tool path on a CNC (Computer Numerical Control) machine tool.

Global Local (Glocal) Supply Chains for Green Economies: An assessment of Greenhouse Gas Emissions

Flexible manufacturing systems, such as Additive Manufacturing, Robotics and Computer Numerical Control (CNC) machines, can be readily deployed and operated in standard warehouse infrastructure providing the opportunity for the on-demand production of a wide variety of goods closer to their point of consumption. This has the potential to shift long-distance logistics towards raw material transport (which can be packed more tightly) and maximise the potential of zero-emission ‘last mile’ logistics. This paper reports a study to demonstrate the merits of Global Local (Glocal) supply chains in terms of the potential reductions in Greenhouse Gas Emissions (GHG). The study used the United Kingdom (UK) and its seven largest cities as the areas of supply and demand with material entering through Dover. The Monte-Carlo simulation showed that distributed production significantly outperforms single location manufacturing and product importing by up to 2-3x.

Digital Evaluation of the Trueness and Fitting Accuracy of a Three-Unit Fixed Zirconium Bridge Fabricated from Different Types of Zirconia and Different Marginal Cement Space Thickness

Abstract Objective The aim of this study was to measure the internal, marginal fitness, and trueness of a three-unit fixed zirconium bridge fabricated using two types of zirconia and different marginal cement space thicknesses. Methods and Materials Thirty-two aluminum master models, constructed by computer numerical control (CNC) milling machines using aluminum rod, representing two prepared aluminum abutments (the upper first premolar and the first molar) were chosen due to differences in shape and dimensions, which may affect adaptation. It may also be considered one of the most common cases in clinical practice and a missing second premolars were used to fabricate a three-unit fixed partial zirconium bridge. A master model was scanned with an intraoral scanner. Fixed dental prostheses (FDPs) were fabricated with two designs (single-layer high-translucent [HT] Katana and ultra-translucent multilayer (UTML] zirconia Katana) and two marginal cement space thicknesses (0 and 25μm for HT and ML). These specimens are divided according to marginal cement space and type of zirconia into four groups, each containing eight samples. Group A: 25-μm marginal cement space with single-layer HT zirconia. Group B: 25-μm marginal gap with UTML zirconia. Group C: 0 μm marginal gap single-layer HT zirconia. Group D: 0 μm marginal gap with UTML zirconia. Fitness and trueness of the fabricated three-unit FDPs were evaluated by scanning the silicone replica of the cement space and analyzing the thickness of the silicone replica in the three-dimensional inspection software (Geomagic Control X, Morrisville, North Carolina, USA). Results Highest mean value of internal gap was recorded at the molar abutment of group D (95.05, ± 3.42 μm), while the lowest was recorded at the premolar abutment of group A (57.12, ± 2.43μm). For marginal gap, the lowest marginal gap was also recorded at the premolar abutment of group A (36.14, ± 3.94μm), and the highest was at the molar abutment of group D (84.74, ± 2.98 μm).For trueness, group A showed the lowest root mean square (RMS) of mean with both abutments compared with group D, which recorded the highest RMS of mean for trueness. Conclusion The marginal cement space thickness affects the FPD internal, marginal fitness, and trueness; single-layer HT (Katana) zirconia shows better fitness and trueness than UTML (Katana).

Optimizing Mechanical Design for an Additively Manufactured Prosthetic Leg

The study discussed in this paper focuses on additive manufacturing (AM) of intricate geometrically structured components of a prosthetic leg. The objective is to optimize the original design to reduce the need for support structures while maximizing stiffness and reducing weight. Making a prosthetic leg lighter can improve the mobility of a person and reduce the energy required to climb stairs, enhancing their quality of life and independence. Traditional manufacturing methods, such as injection molding and computerized numerical control (CNC) machining, have limitations in terms of design flexibility. The study used Selective Laser Melting (SLM) technology with 316L-A stainless steel powder. The optimization process focused on the knee, upper leg, lower leg, hydraulic, and oil support system. The workflow procedure for additive manufacturing was discussed. Overall, the study successfully reduced the weight of the prosthetic leg by 50% from the original model.

A Condition and Fault Prevention Monitoring System for Industrial Computer Numerical Control Machinery

A Condition and Fault Prevention Monitoring System for Industrial Computer Numerical Control Machinery

Adaptive positioning technology of film cooling holes in hollow turbine blades

Film cooling technology is widely used in hollow turbine blades of aero-engine with a high thrust-to-weight ratio. The positioning accuracy of film cooling holes directly affects the uniformity and adhesion of the cooling film on blade surfaces. Two main factors affect the positioning accuracy of film cooling holes, i.e., the profile deformation of the blades during manufacturing and the blade clamping error in computer numerical control equipment. The positioning technology of film cooling holes has rarely been investigated. In this study, an adaptive positioning method is proposed to provide a reference for innovative research in this field. First, this study proposes a method for measuring and compensating blade clamping error based on the point cloud data of the entire blade surface obtained with optical scanning equipment by combining the rigid-body transformation theory and three-dimensional point cloud matching method. Second, owing to the complex overall deformation of the blade surface, this study innovatively focuses on the deformation of each slice from a local perspective. Furthermore, the deformation of each slice is decomposed into bending, torsion, and uneven shrinkage. The bending and torsion deformations are compensated based on the two-dimensional rigid-body matching method, while the remaining uneven shrinkage deformation is compensated by the position mapping method. The effectiveness and accuracy of the proposed method are qualitatively and quantitatively verified by the adaptive positioning results of film cooling holes in actual and test blades. The maximum spatial position and angle deviations are 0.0561 mm and 0.6946°, respectively.

Terahertz couplers based on branch lines and waveguide resonators

AbstractThis paper presents two waveguide quadrature hybrids in the WR‐3 band, which are designed to be fabricated by computer numerical control milling process with relaxed branch width requirements. An E‐plane four‐branch directional coupler gives an amplitude imbalance less than 0.8 dB and a phase difference between 88° and 94° from 240 to 324 GHz. Another design is an H‐plane bandpass coupler composed of cavity resonators, showing a bandwidth of 2% near 300 GHz.

Capacity Building Needs for Computer Numerical Control Machines Teachers’ Effectiveness in Technical Colleges in Delta State.

Capacity Building Needs for Computer Numerical Control Machines Teachers’ Effectiveness in Technical Colleges in Delta State.

The Basic Concept and Application Status of Laser Induced Forward Transfer

Laser Induced Forward Transfer (LIFT) is a new type of transfer method. It uses high-energy laser as an energy source to irradiate solid or liquid materials, allowing them to be emitted onto the receiving substrate under the force of steam to achieve the transfer of material. Nowadays, although most of the work on LIFT is still in the laboratory stage, compared to the traditional process of LIFT, its nozzle free characteristics, pixel-based transfer method, make it have high production efficiency, universality of materials, and compatibility with Computer numerical control (CNC) machine tools. In this review, the fundamental principle of LIFT is introduced and the great potential of LIFT in many fields is presented and analyzed, including Three-dimensional (3D) bioprinting, industrial manufacturing, energy storage material manufacturing, new-type energy and so on. The conclusion is that if the application of LIFT in the manufacturing field can be achieved, the efficiency and flexibility of modern digital production will be greatly improved. The LIFT method has great development prospects in the manufacturing field.

Lost Wax Casting

The lost wax production process is an intermediate step in converting a design idea that has been 3D printed from Polylactic Acid (PLA) plastic into a functional part via metal casting processes. This work offers an experimental assessment of the benefits accompanied by the lost-wax method, from both energy and economic-related aspects. The methodology of this work is represented by a sequence of steps that involve converting a 3D modeled and printed part (an investment casting tree), into a metal part, which in this case is made out of Aluminum. Aluminum was obtained from recycled products (i.e., beverage cans). The first couple of steps revolve around obtaining a 3D printed part of the desired 3D model, that can be created using a multitude of readily available Computer Aided Design (CAD) software. The 3D printed part is then utilized to create a plaster mold, which is followed by a firing step to get rid of the temporal 3D printed part to leave room for the casting metal. An energy assessment was carried out to compare the lost wax method and conventional machining (i.e., computer numerical control (CNC) machining). It was shown that to obtain the exact same functional part using the lost wax method, 12.124 kWh of energy is required, versus that of 17.297 kWh for CNC machining. Moreover, normalized costs of 0.067$/g and 0.096$/g were attributed to the lost wax and CNC machining, respectively, showing an almost 70% reduction in price when opting for the lost wax method.

Monitoreo de la confiabilidad del sistema hombre-máquina del área de mecanizado mediante la distribución de Weibull

This publication presents the development of a method that seeks to monitor the parameters β (shape) and η (scale) for each component-subsystem combination following the Weibull distribution, necessary for the calculation of the reliability of the man-machine system in the machining area. This system defines the workshops of the metal-mechanic, with high-mix and low-volume batch production where conventional and Computerized Numerical Control (CNC) machines are involved, which share the manufacturing of parts that sometimes are unique, or their manufacturing period is short. The design of the man-machine system is based on the analysis of the failures of non-conforming parts in the machining area and on the failure rates, which the statistical model is developed for its evaluation, considering the 2-parameter Weibull distribution, and a redundant system with series-parallel configuration. The results obtained were based on the theoretical-practical, using mathematical and statistical models, as well as the Study Case. With the use of mathematical and statistical models, it is demonstrated that the probability of failure (risk) of the man-machine system is time-dependent and is generated by mechanical type stresses, which occur in the manufacture of parts.

A Thermal Error Prediction Method of High-Speed Motorized Spindle Based on Pelican Optimization Algorithm and CNN-LSTM

Given motorized spindles’ extensive periods of prolonged high-velocity operation, they are prone to temperature changes, which leads to the problem of thermal error, leading to diminished precision in machining operations. To address the thermal error issue in motorized spindles of computer numerical control (CNC) machine tools, this study proposes a pelican optimization algorithm (POA)-optimized convolutional neural network (CNN)–long short-term memory (LSTM) hybrid neural network model (POA-CNN-LSTMNN). Initially, the identification of temperature-sensitive locations in the spindle system is performed using a combination of hierarchical clustering, the K-medoids algorithm, and Pearson’s coefficient calculation. Subsequently, the temperature data from these identified points, along with real-time collected spindle thermal error data, are employed to construct the model. The Pelican optimization algorithm is used to enhance the model parameters to achieve the best performance. Finally, the proposed model is subjected to a comparative analysis with other thermal error prediction models. Drawing from the experimental findings, it is evident that the POA-CNN-LSTMNN model exhibits superior prediction performance.

Sequential procedure to investigate the optimal ranges of process parameters for the FSW of AA8090

The main purpose of this experiment is to evaluate the optimum range of process parameters for Friction Stir welding of AA8090. In the present research work, an experiment has been made to join AA8090 alloy using friction stir welding (FSW) at different rotational speed, welding speed and tilt angle settings. The FSW was done on the CNC (Computer Numeric Control) Vertical milling machine using fixture and a cylindrical threaded tool. For designing experiments, the steepest ascent technique (Factorial Design) was used considering tilt angle, welding speed and rotational speed as input parameters and ultimate tensile strength (UTS) as an output parameter. The metallurgical and mechanical characteristics were investigated and considered while providing the sequential procedure for the optimal range. The optimum range of values observed at tilt angle (1.1° to 1.9°), welding speed (24.6 to 48.2 mm min−1), and rotational speed (1428 to 1876 r min−1). The maximum value of UTS (365 MPa) is obtained at rotational speed of 1652 r min−1, welding speed of 36.4 mm min−1, and tilt angle of 1.5°. Scanning electron microscopy and optical microscope were used for fractrography and microstructural analyses of the joints. The finer grains are observed in the NZ equated to the HAZ and TMAZ.

Spindle Thermal Error Prediction Based on Back Propagation Neural Network and Hybrid Taguchi Genetic Algorithm for a Computer Numerical Control Machine Tool

Spindle Thermal Error Prediction Based on Back Propagation Neural Network and Hybrid Taguchi Genetic Algorithm for a Computer Numerical Control Machine Tool