CNC Machining Center Research Articles

Development of a computer vision-based system for part referencing in CNC machining centers

Development of a computer vision-based system for part referencing in CNC machining centers

Minimization of Total Variable Cost through Determination of Batch Transfer Size at m Serial CNC-Machining Centers

Background: In a batch production series consisting of several process stages for discrete products, the determination of the transfer batch size greatly affects the batch waiting time. For production using a Computer Numerical Control (CNC)-machining center, several process stages can be carried out on one machine with quick setup. The use of a single machine for all stages of the process certainly does not require transfer to the next machine. Thus, there are no material handling costs. However, the use of a single machine will result in longer batch waiting times as the production batch size increases. An increase in the batch waiting time will result in an increase in work-in-process (WIP) inventory cost. This research was conducted to reduce the total variable cost consisting of WIP inventory cost and material handling cost. Methods: This research was conducted in two steps. The first step is to divide the process stages, I into m serial CNC machining centers, where in this study I=m. The second step is to determine the same size of transfer batch, Qij for a certain number of transfers, J that produces the minimum total variable cost. Results: The results showed that J=5 resulted in a total variable cost of Rp. 146,800.00, while J=10 resulted in a total variable cost of Rp. 178,900.00. Conclusion: In conclusion, the total variable cost decreases if the size of transfer batch is reduced to a certain amount and will increase again along with the reduction in the size of transfer batch.

On the milling strategy in machining curved surfaces based on minimum stress concentration by a 3-axis machining center

Three-axis computer numerical control machining centers are commonly used in machining due to their simple operations. When machining curved surfaces, the 3-axis CNC machining centers use interpolation line segment to fit the curved surfaces. The quality of the machined surface is affected by the length of the interpolation line segment. Sharp corners are formed at the junction of straight segments. The appearance of sharp corners will lead to increased stress concentration. To study the relationship between machined surface quality and interpolation straight line, this paper establishes the mathematical model of surface topography in ball-end milling multi-curved surfaces by a 3-axis milling center with considering the acceleration and deceleration controls. Based on the surface topography model, the stress concentration factor is analyzed in machining curved surfaces with different lengths of interpolation lines. The results show that the stress concentration factor decreases with the increase of the central angle when the length of interpolation lines and the radius of curvature are kept in constant, while decreases with the increase of the radius of curvature when the length of the interpolation lines and the central angle are held on. Moreover, the stress concentration factor increases as the length of the interpolation lines increases when the radius of curvature and the central angle are kept in constant. A method for selecting proper length of interpolation lines based on the stress concentration is proposed. In addition, the quality of the machined surfaces can be improved through the optimization of the tool path.

Drilling parameter analysis of hybrid composites (Al/B4C/graphite) using grey relational and Taguchi techniques

Application of composite materials has been increasing worldwide especially in production industries. In drilling operation, standard of hole is the basic demand in numerous applications. The choice of optimized drilling parameters is extremely vital for good hole quality. Our objective is to optimize the parameters involved in drilling of aluminium /boron carbide/ graphite hybrid composite materials to get good quality holes. A series of drilling experiments are conducted in CNC machining centre on the hybrid composite specimen slabs of size 100 mm × 100 mm × 10 mm, made-up by stir casting technique. Our work is to analyse the consequences of drilling parameters like spindle speed, feed and drill tool diameter on thrust force, torque, surface roughness and roundness error. The experimental results are collected individually on L27 orthogonal array and analysed by Signal – Noise (S/N) quantitative relation and grey rational analysis with an objective to optimize the drilling parameters to reveal the dominant factors that have an effect on the responses mentioned.

Optimization of drilling process parameters for self-lubricants reinforced aluminium metal matrix composites

Aluminium matrix composites (AMCs) find a wide spectrum of application in various fields of engineering and technology. Owing to the below par inherent characteristics of unreinforced AMCs, reinforcements are used to improve the characteristics of AMCs. Reinforcing the self-lubricating graphite (Gr) and molybdenum disulphide (MoS2) in aluminium matrix was found to improve the machinability and surface finish of the composites which in turn enhances the application prospects. In the current investigation, aluminium alloy 2219 (AA2219) was reinforced with Gr and MoS2 and the composites were fabricated by conventional casting technique. Drilling behavior of the composites were investigated by conducting drilling experiments in CNC machining center and surface roughness of the holes were measured. Experiments were designed by full factorial method. Results of the experiments portrayed that the composites with Gr as reinforcement exhibited better drilling behavior when compared with MoS2 reinforced AA2219 composites.

Prediction of energy consumption in the leadwell v-40 it CNC machining center through artificial neural networks

Energy consumption in machining processes has become a problem for today's manufacturing industry. The use of neural networks and optimization algorithms for modeling and prediction of consumption as a function of the cut-off parameters in processes of this type has aroused the interest of research groups. The present work used artificial neural networks (ANN) to predict the energy consumption of a Leadwell V-40iT® five-axis CNC machining center, based on experimental data obtained through a factorial experimental design 53. ANN was programed in Matlab®. From the study was concluded that the depth per pass (Ap) is the variable that has the most influence on the prediction model of energy consumption with a 77% of relative importance, while the feed rate is the least relevant with 9% of importance.

Mirror surface finishing of hardened stainless steel using spherical PCD tool

At present, the surface precision requirements for mold and die parts are extremely high. Especially in the precision mold and die cavity for ELD lenses, several mirror surfaces for automotive lens parts, and general camera lenses that required a few tens or a single nano-level like a mirror-finished surface. This final process is difficult to achieve with the conventional cutting edge of ball-nose end mills. In addition, it is commonly performing a very long time by manual polishing of the skilled worker after machining. To the problem, we purposed to develop a sintered polycrystalline diamond (PCD) tool with a simple spherical cutting part. This PCD tool is a novel method for the final process of the small molds and dies cavities with high precision. A distinctive feature of its cutting can achieve a mirror-finished surface by full automation on a CNC machining center. This study aims to clarify the basic machining characteristics and verify its effectiveness on the hardened stainless steel commercial STAVAX with the hardness of 54 HRC for small mold and die cavities. As a result, we can clarify the chip generation mechanism, finish surface accuracy, internal crystal structure state, and residual stress characteristic of this processing method. It also shows that the manual problems related to mirror finishing of the precision mold and die cavity can be solved under the actual mold manufacturing process by consecutive conditions.

ANÁLISE EXPERIMENTAL DE ESTAMPABILIDADE DA CHAPA DE AÇO ASTM A653 DURANTE O PROCESSO DE ESTAMPAGEM INCREMENTAL POR PONTO ÚNICO E AVALIAÇÃO DA RUGOSIDADE IMPRESSA NA SUPERFÍCIE CONFORMADA

This study aims to evaluate the behavior of ASTM A653 CS-A G90 steel in the process of Incremental Sheet Forming – ISF, based on the following parameters: diameter of the tool (Dt in mm) and the vertical step size between consecutive contours (∆z in mm). The experiments were based on a variation of the ISF process, called Single Point Incremental Forming - SPIF. In this study, seventeen tests were conducted using a punching tool with diameters (Dt ) of 5, 6 and 8 mm and vertical steps (∆z) of 0.4, 0.6 and 0.8 mm, intending to evaluate the true strain to the ISF process and the surface finishing measured by roughness parameter (Rz). Whereas, for the execution of practical testing, the resources used were a CNCmachining center with three axes, tools for incremental forming and a sheet-press device. As a result, greater depths were achieved using an incremental step of 0.4 mm. In additional tests, it came to attention that the diameter of the tool was also an important parameter when it is desired to increase the formability and greater depths are obtained when using small diameters. It can be observed yet, there is a tendency to increase the roughness parameter Rz when using greater vertical steps ∆z

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Analysis of four-edge mill modality and stress deformation based on ANSYS

In mechanical design, we often need to use CNC machining center, in which milling cutters are our indispensable and most common processing tools, milling machines. We often use two-edged milling cutters, three-edged milling cutters, four-edged milling cutters. In order to analyze the milling cutter, we need to draw the 3D modeling of the milling cutter in UG, import the 3D model into the workbench to analyze the tool finite meta, analyze a four-edged mill, analyze whether the natural frequency will resonate with the machine tool. Find 10th-order modes, stress analysis of tools, deformation analysis. Topology optimization is carried out to enhance existing effects, reduce costs and improve efficiency.

A novel approach to CNC machining center processing parameters optimization considering energy-saving and low-cost

NC machining is currently a machining method widely used in mechanical manufacturing systems. Reasonable selection of process parameters can significantly reduce the processing cost and energy consumption. In order to realize the energy-saving and low-cost of CNC machining, the cutting parameters are optimized from the aspects of energy-saving and low-cost, and a process parameter optimization method of CNC machining center that takes into account both energy-saving and low -cost is proposed. The energy flow characteristics of the machining center processing system are analyzed, considering the actual constraints of machine tool performance and tool life in the machining process, a multi-objective optimization model with milling speed, feed per tooth and spindle speed as optimization variables is established, and a weight coefficient is introduced to facilitate the solution to convert it into a single objective optimization model. In order to ensure the accuracy of the model solution, a combinatorial optimization algorithm based on particle swarm optimization and NSGA-II is proposed to solve the model. Finally, take plane milling as an example to verify the feasibility of this method. The experimental results show that the multi-objective optimization model is feasible and effective, and it can effectively help operators to balance the energy consumption and processing cost at the same time, so as to achieve the goal of energy conservation and low-cost. In addition, the combinatorial optimization algorithm is compared with the NSGA-II, the results show that the combinatorial optimization algorithm has better performance in solving speed and optimization accuracy.

FEM based investigation on thrust force and torque during Al7075-T6 drilling

As modern industry advances, the demand for more time and cost effective machining is rising. In order to achieve high levels of standard during machining it is necessary to employ sophisticated techniques for precise prediction of various important parameters that relate to the machining processes. Such technique is the implementation of finite element modelling (FEM) which can become a valuable tool for researchers and industry engineers alike. In this work, the 3D modelling of Al7075-T6 drilling process with solid carbide tooling is being presented. DEFORM3D™ finite element analysis (FEA) software was utilized for simulating the drilling process based on frequently used cutting conditions; cutting speed of 100m/min and feed of 0.15mm/rev, 0.20mm/rev and 0.25mm/rev respectively. In order to approximate the complex phenomena that occur during drilling, the most critical factors were considered in the presented model such as the developed friction, heat transfer and damage interaction between the tool and the workpiece. Additionally, a validation of the generated results for thrust force and torque was performed by comparing the simulated results with experimental data. Three drilling experiments were carried out with the aid of a CNC machining center and a four component dynamometer in order to acquire the experimental values of thrust force and torque. Most of the simulations yielded results in accordance to the experimental ones with the agreement percentage reaching 95% in most cases for both the thrust force and torque, confirming the validity of the models and the accuracy of the simulated results.

Method for Data-Driven NC-Code Optimization based on Dexel Material Removal Simulation and Tool Holder Vibration Measurements

This paper presents a novel approach for data-driven NC-Code optimization, based on the integration of dexel-based material removal simulation and an instrumented tool holder, capable to measure vibrations during milling close to the cutting zone. Considering measured cutting vibrations, machine tool axis and NC-line data, a model has been developed optimizing cutting parameters to generate a NC-Code right after a first machining trial with mitigated vibration effects. Different modules for human-assisting vibration visualization and automated optimization of cutting parameters are presented, using milling use-cases implemented on a CNC machining center.

Study upon the kinematic simulation of the incremental forming carried-on using a serial industrial robot

Incremental forming with contact between tool-sheet metal workpiece in a single point is an unconventional process which allow the user to manufacture parts by combining the vertical movement of the tool along Z-axis and the horizontal movements of sheet metal workpiece, which are performed in XY plane. As technological equipment able to control coordinated movements on three axes, CNC machining centers and industrial serial robots with six degrees of freedom are the most suitable. The paper introduces a study regarding the use of robots as technological equipment for the process, by means of simulation. Supplementary degrees of freedom and singularities avoidance are also considered.

Life Cycle Analysis of Computer Numerical Control (CNC) Machine Components

The nucleus of this concept and system is directly focused on a 'computer numerical control' (CNC) turret lathe and milling machine tool systems. These concepts focus specifically to this category of engineered systems. Quality design review for quality service systems is a unique concept. Standard product service systems are qualitative and subjective in nature. A quantitative system identifies Key Predictive Attributes (KPA’s), which identifies a new concept application technique and applies quantitative methods to these attributes to develop a systemic process of analyzing and monitoring the system. This research is reviewing the specific projection of service outcomes for Machine tool CNC machining centers (Lathes and Milling Machines). The specific key predictive attributes are the elements being utilized in the newly created modular function in this research, to assess the potential impact of discrete elements of these attributes as it affects the occurrence of equipment down time for a system which will work to quantify the service quality of the maintenance process. This project is unique in that currently there is no system which utilizes methods or tools, that proactively gather, analyze, assess, and project outcomes of equipment “Down Time” of the Service Quality process. The innovative position of this analysis is one of actual variable tolerances, versus a more traditional nominal referenced variable reference. What makes this research unique additionally is the system is pre-service and not post service reporting of actual down time of the equipment. This research is much more than pro-forma estimate of service outcomes. Another unique aspect of this method is that it will establish tangible tolerances to assess the performance of the Design Review and Service Quality process and not just rely on subjective nominal values. Mathematical Upper Control Limits (UCL) and Lower Control Limits (LCL) will be programmatically developed based upon the system data. This system tool will develop programming algorithms which will propel this current process from a subjective qualitative process to become a robust quantitative projection tool. The novelty in this research is the development of a quality index through the creation of the new Moriarty/Ranky Transform approach.

Method of Postures Selection for Industrial Robot Joint Stiffness Identification

Industrial robots are being widely applied to machining operations, and are gradually becoming competitive with traditional CNC machining centers. Obtaining accurate stiffness values of robotic joints is the foundation for deflections compensation in case of large cutting forces. A number of factors influence the accuracy of joint stiffness identification, especially robotic posture. This paper proposes a robust and accurate method for selecting suitable postures in the joint stiffness identification. The identification process of the joint stiffness matrix is presented, an index considering both the dexterity and the condition number of the observation matrix is then developed, and the procedure for postures selection based on it is provided. The results of simulations and experiments show that the proposed method is more robust and accurate than classical method.

WITHDRAWN: Optimization and modeling of drilling variables on AMCs using Taguchi technique and regression analysis

This research work explores the optimum variables for the drilling process of AA7075 matrix composite filled with 10 wt% ZrO 2 particles was synthesized via stir casting route. A Taguchi approach was used to determine the optimum variables such as rotational speed (500, 750, 1000 and 1250 rpm), feed rate (0.06, 0.08, 0.10 and 0.12 mm/rev) and depth of cut (1.0, 1.5, 2.0 and 2.5 mm) on the surface roughness (SR) of the composite. The experiments were performed on a CNC machining centre using HSS tool. The signal-to-noise (S/N) ratio and analysis of variance (ANOVA) was applied to find out the optimum parameters and also compute the notable effects of factors on the SR. The result reveals that, the rotational speed of 1250 rpm; feed rate of 0.12 mm/rev and depth of cut of 1.5 mm were achieved the low SR. The ANOVA results understood that the feed rate was the most impactful factor on SR subsequently by rotational speed with a contribution of 60.37% and 32.66% respectively. The interaction effects of variables on SR were also reported. At last, regression equation was formulated to predict the SR and it was compared with experimental SR.

Preliminary Investigation of Delamination Factor for Drilling Wood Plastic Composites (WPC)

This study examines the effect of the delamination factor on wood composite drilling. Drilling is one of the most important machining operations in the manufacturing process, operating in a variety of ways to make life better every day. The preliminary experiment focuses on the implementation of three drilling strategies to determine the most appropriate for drilling composite and to identify the effect of the machining parameters of wood plastic composite (WPC) drilling. The CNC machining centre is used at the factory of the local company to assist them in the provision of certain production inputs. It is observed that the single step drill peck is the best suited strategy for drill WPC with less delamination at the entrance and exit holes compared to the other two methods, 2-peck and 4-peck drills. Hole tends to create a peel-up and to force the delamination down heavily along the hole edge when using the 4-peck process while the least peel-up pattern happens when using a single-step method. The findings also show a large amount of peel-up delamination as the feed rate increases. Therefore, the final results are also useful in understanding the relationship between the drilling parameters and the cutting experiments.

Analysis of the algorithms of the movement of forming during planetary boring and milling on CNC machines

The article discusses methods for processing large-diameter holes in CNC machining centers. The possibility of implementing each method on existing equipment in the form of standard cycles or macro programs is analyzed.

Development of a mobile application for monitoring and controlling a CNC machine using Industry 4.0 concepts

Industry 4.0 comprises a set of technologies that allow the interconnection, monitoring, and controlling of manufacturing processes. Today it represents a key point for the modern industry. The current work presents an Industry 4.0 system developed for monitoring and controlling a 5-axis CNC machine center, in real time, through a mobile device, providing important feedback information for users and manufacturers of the machine. Given that response time is crucial in such applications, we conducted an experimental investigation to examine the system latency with distinct database structures, based on SQL and NoSQL. The results suggest that the non-relational structure (NoSQL) presented lower response times and is, thus, best suited for the application in hand. The system allows monitoring and controlling of any CNC machine remotely—given that a middleware for connecting the machine is provided—in real time, presenting new possibilities from the perspectives of machine tool builders and shop floor management.