Numerical Control Program Research Articles

Development of an expert system for technological support of required roughness when machining hardened steel parts on numerically controlled machines

This work addresses the problem of improving the surface quality of parts of rotation bodies, which are made of hardened steels, in the course of their machining on lathes with numerical program control. The research object was the surface roughness of parts. The methodology involved system analysis and synthesis, artificial neural networks, fuzzy logic, experiment, and processing of experimental results. A decomposition scheme for the expert system structure was developed, which can be used as the basis for formulating requirements to a future expert system for monitoring and prediction of roughness parameters. It was established that the models currently applied to describe the relationship between surface quality and the technological regimes used to ensure the technological level of roughness give a high error of over 20%. The possibility of using models that apply artificial intelligence and contain neural network blocks and decision-making devices based on fuzzy logic is substantiated. It is shown that such a combination makes it possible to customize the system for processing parts of a certain production range, as well as a more correct assessment of the onset of catastrophic wear of cutting tools. The neuro-fuzzy model was confirmed to have an error of less than 10%, which is significantly lower than when using spectral or correlation models. According to the testing results, the proposed expert system for monitoring and prediction of roughness parameters enables a 2.5-fold reduction in the scatter of roughness parameters under an increase in tool wear, compared to without its application. Thus, the proposed system makes it possible to assess the level of cutting tool wear more correctly and determine the onset of its limit state.

Metrological characterisation of tool pre-setting optical systems based on 2D imaging

Accurate tool geometry is vital in modern computer numerical control machine tools for ensuring the accuracy of the manufactured parts in machining processes. The tool pre-setting optical systems play an important role by establishing accurate, efficient, and repeatable tool data for cutting tools varying from macro to micro size tools. The tool data is later utilised by the numerical control programs to accomplish precision machining operations with the required accuracy. However, the traceability of tool pre-setting optical systems is not guaranteed due to the lack of specific international standards, and there is a strong need of establishing a traceable measurement process which requires calibrated reference artefacts. In this work, we have established the metrological characteristics of an image-based tool pre-setting optical system based on ISO 15530 part 3. For this purpose, an artefact with sharp cutting edges was manufactured from a calibrated cylindrical gauge pin, measured on a coordinate measuring machine by two different approaches, and the impact of the edge radius is incorporated in the measurement process. The artefact was later employed in the performance verification of the optical system for on-machine tool characterization analogous to the production workshop environment, and the measured outcome of the optical sensor was evaluated with the developed metrological approaches. Experiments have shown the applicability of the measurement procedures and the relevance of the proposed reference artefact for the characterisation of image-based tool pre-setting optical systems.

Automated Process Planning System for Machining Injection Molding Dies Using CAD Models of Product Shapes in STL Format

In this study, we developed a method for automatically generating computer-aided design (CAD) models of injection molding dies. The method only required 3D CAD models of products in the Standard Triangulated Language (STL) format as the input information. We also developed a system for automatically generating numerical control (NC) programs by automating the system process planning necessary for machining the injection molding dies. The method generated CAD models of the injection molding dies by dividing the STL files of the products into triangular meshes on a specified split plane. For injection molding dies with several free curved surfaces, we acquired the tool positions of a ball end mill (as approximated by a spherical shape) and flat drill (as approximated by a cylindrical shape) from the geometrical relationships of the triangles constituting the CAD model. We generated a CAD model of an injection molding die using the proposed method with respect to the CAD model of a product shape to verify the validity of the developed system. Then, we machined the product based on the NC programs and tool position. In addition, we injection molded a product with a machined die to mold it into its original product shape.

PROSES PRODUKSI STAND GRIPPER MENGGUNAKAN CNC MILLING 3 AXIS TIPE WELLE CV 1060

One of the efforts made in the education sector to increase the need for human resources is to implement a system that can create a workforce that is ready to apply their knowledge in the field of work. To apply the knowledge they have gained while attending lectures, students are given the opportunity to go directly to a company which is usually called an industrial internship. While carrying out industrial internships at Solo Technopark, students are placed in the CNC design and machining section. The stand gripper production process goes through several stages, namely designing product images, creating a numerical control program with Autodesk powermill software, and computer numerical control milling (CNC milling) machining processes. The problem that occurs during the stand gripper production process is that there is very little material gripping due to the size of the initial material which has very little difference with the size of the finished workpiece. The solution to this problem is to ensure strong clamping and the help of parallel blocks so that the material does not move during the execution of the workpiece.

Multi-sensor monitoring of powder melting states via melt pool optical emission signals during laser-based powder bed fusion

The instability of the powder melting states is a common problem in laser-based powder bed fusion of metals (PBF-LB/M). Optical signal monitoring based on melt pool emissions has great potential to solve this problem, but there is a lack of research on the inherent correlations between the optical emissions and powder melting states. In this paper, a synchronous monitoring method of multi-sensor signals based on automatic trigger by numerical control programming was proposed. Then the relationships between the characteristic changes in melt pool signals and the powder melting state variations were carefully examined based on the statistical method. The results showed that the data collection method achieved synchronous monitoring of multi-sensor signals in the target process. The combination of the melt pool light intensity and melt pool area can effectively capture powder melting state variations owing to the changes of powder thickness. Among them, the melt pool light intensity can accurately monitor powder melting state variations caused by the powder thickness of 30 μm to 210 μm. While the melt pool area is susceptible to powder melting state variations caused by the powder thickness of 210 μm to 300 μm. Meanwhile, two emission characteristics (mean intensity and standard deviation) of the optical emissions were closely related to the melting states and stability of the powder.

Utilizing Virtual Laboratory to Improve CNC Distance Learning of Vocational Students at Higher Education

This research develops learning materials for Computer Numerical Control (CNC) programming courses based on virtual reality technology. The impact of the Covid-19 pandemic on social activities, one of which is the educational aspect, has changed the learning pattern to a massive one where the learning process that should be carried out face-to-face, but now must carry out distance learning. Therefore, alternative learning media is needed to support the practicum process from a distance by utilizing virtual reality technology that is simulated using digital devices. The Software engineering models, namely: requirements, design, implementation, verification, and maintenance phases are the five primary stages used in this study, which uses the waterfall development model research method. The feasible of the virtual laboratory obtained the results of material validation, learning media, and small group trials of 12 diploma students of Mechanical Engineering at Universitas Negeri Padang. The findings of the study found that small group trials in CNC virtual laboratory can be successfully utilized in CNC programming courses. This research is expected to have implications for improving learning outcomes in CNC programming courses by using virtual laboratory technology in creating a conducive and quality learning atmosphere, so that the learning material provided can be accepted by students.

Energy consumption optimisation for machining processes based on numerical control programs

Machining processes comprise numerous energy consumption activities. Given the significance of the circular economy and manufacturing sustainability to modern societies, it is paramount to design effective methodologies to accomplish energy-efficient machining processes. With this aim, this research presents a new approach of energy consumption optimisation for machining processes based on numerical control (NC) programs. In the approach, the following innovative characteristics are exhibited: (i) An energy model is systematically established based on a detailed analysis of energy consumption activities in machining processes; (ii) NC programs for specific machining processes are assessed in detail and popularised into the energy model for instantiation; (iii) An optimisation algorithm hybridising the genetic algorithm and the ant colony algorithm is designed to minimise air-cutting toolpaths to optimise the energy model. Two case studies were conducted to validate the presented approach. The case studies revealed that the accuracy of the energy model was 95.3% of the actual energy consumption. The studies also showed that, based on the optimised energy model, the total length of air-cutting toolpaths was reduced by 43.8%, and the total machining time was diminished by 25.8%. It can be concluded that the developed approach can achieve substantial energy savings, and therefore it is highly promising to support machining industries to meet their sustainable targets.

Analysis and Control of Precision Machining Error for Spatial Angle Parts of Remote-Sensing Camera

Aiming at the problem of low machining accuracy of remote-sensing camera parts with spatial angle, this study analyzed the causes from human, machine, material, method, environment, and measurement, and proposed an experimental analysis method based on the spatial rotation of machine tool spindle according to the linkage machining function of the five-axis machining center. The cutting experiment was carried out through the self-built benchmark of the machine tool, and the machining errors of the machine tool spindle with different spatial angles were studied. The precision machining of the parts with spatial angles was realized by taking measures such as machine tool correction and numerical control program compensation. The experiment proved that this method is feasible and effective.

Studies on the Numerical Control Programming for Multi-Axis Machining of Turbomolecular Pump Rotor

Turbomolecular pumps (TMPs), boasting advantageous high pumping rates, stability, and cleanliness, have been widely used in the semiconductor and photoelectric industries. In the aviation industry, the lightweight rotors of turbomolecular pumps can enhance the performance of generators. With technological advancements and increased industrial performance demands, various designs for turbomolecular pump rotors utilizing twisted and curved blade surfaces have been proposed. This increase in complexity runs parallel with machining difficulties. Contact and noncontact reverse engineering equipment was used to reconstruct a computer-aided design (CAD) model of turbomolecular pump rotors. The machining of thin and long blades, cutting tool arrangement, and toolpath was planned. Postprocessing was used to convert the toolpath into numerical control (NC) programming codes, which were combined with solid model cutting simulation software to verify the efficacy of the generated machining NC program for turbomolecular pump rotors. A five-axis horizontal machining center (CK type) with aluminum alloy AL6061-T6 was used to conduct actual machining tests measuring the efficiency of the machining methods. The rapid prototyping (RP) blocks can be creatively used as a jig and stuffed between the blades to suppress the chatter problem during processing, and the roughness of the surface of the blades can be reduced from 4.4 μm to 1.3 μm. The processed rotor can meet the flow test requirements, and the overall research can be used as a reference for the industry.

Immersive Learning Experience Design (ILXD): Augmented Reality Mobile Application for Placing and Interacting with 3D Learning Objects in Engineering Education

The Computer Numerical Control (CNC) machine operates based on a numerical control program generated semi-automatically by a Computer Aided Manufacturing (CAM) system or manually by the operator. Repeated practice is required to operate a CNC machine. For an inexperienced operator (student), the practicum requires extensive use of materials and cutting instruments. In the meantime, the number of laboratory equipment for the CNC programming practicum remains limited, and the 3-axis CNC milling machine training unit is inadequate for the number of students. For this reason, we need a medium that can simulate the machining process to aid students in their early stages of learning. This research aims to create a mobile application for milling machine visualization based on augmented reality. This augmented reality (AR) application, "MM: CTU 3-Axis," or Machine Milling CNC Training Unit 3-Axis, was designed with 3D virtual objects to provide students with knowledge and practical experience. The application development model used Multimedia Development Life Cycle (MDLC). This research yields an Android-based augmented reality (AR) application called "MM: CTU 3-Axis" that does not require markers. The development and verification results demonstrated that this application could aid in learning CNC programming and machining practicum, as well as reduce the cost of using cutting tools and the cost of using materials due to repeated experiments on CNC machines.

Study on Process Design Based on Language Analysis and Image Discrimination Using CNN Deep Learning

At present, machining with numerically controlled (NC) machine tools is mostly performed by NC programs generated by computer-aided design and computer-aided manufacturing (CAD/CAM) systems. However, even if the machining shape to be machined is the same, there are numerous machining processes involving a series of operations such as determining the machining area, machining order, and machining conditions. These are entrusted to the user, and automation is difficult. In addition, these tasks depend on the experience and know-how of skilled engineers, and it is very difficult to convert them into algorithms and reflect them in the creation of NC programs. Therefore, in this study, artificial intelligence (AI) was used for the process design of multi-tasking machine tools, with the goal of determining and automating the process design using shape examples. We propose a shape recognition method that includes image analysis by AI. This image analysis makes it possible to determine the characteristics of the machining shape, and the machining operator can easily judge the machining process based on the CAD model. Furthermore, because there are shapes that cannot be determined from image data alone, shape features are also extracted from the STEP file of the CAD model. A language analysis of the STEP file can find the characteristic components and their numerical information to determine the coordinates of the shape features. By combining image analysis and language analysis, the method can easily judge the process based on the information in the CAD model. Finally, using the generated learning model and analysis program, we conducted a test to determine whether a multitasking machine tool is necessary for machining.

Numerical Control Simulation and Programming Based on SinuTrain Bearing Bracket (Five-axis)

At present, the development of numerical control processing technology has entered a new period and has gradually developed in the direction of artificial intelligence. Along with the development of science and technology in recent years, the present stage of our country has made a significant breakthrough in the application of numerical control processing technology. Hence, learning to master CNC machining technology is necessary. Numerical control simulation software is used to NC machining the bearing bracket (five-axis), and numerical control simulation software SinuTrain is used to NC programming the parts and simulation verification of the machining process. SinuTrain is a CNC training software that functions exactly like the controller itself. The use of this software for bearing bracket (five-axis) numerical control simulation and programming, can make us master the use of this software, and can also help us understand the mechanical processing process and programming technology.

Research on Cutting Parameters Database Based on Spacecraft Product Characteristics

Cutting parameters affect the production and processing efficiency and the quality of products. The characteristics of single-piece and small-batch production of spacecraft products result in a large number of cutting parameters. Due to the lack of centralized management methods, cutting parameters in the production site are not unified, which seriously affects the processing efficiency and quality of products. In response to a large number of cutting parameters and the lack of centralized management, the production resource library is completed by establishing a spacecraft product feature pedigree. Taking the product characteristics as the carrier, the production resources as the optional factors, and the forces in the cutting process as the evaluation criteria, the whole life management mechanism of cutting parameters is established to unify the cutting parameters in the production process and complete the establishment of the cutting parameter database. The interface between the programming platform and the cutting parameters library is developed for a low reuse rate of cutting parameters. With typical features as the carrier, the cutting parameters are packaged and transmitted to the programming platform to provide reliable cutting parameters for feature automatic programming, which improves the reuse rate of cutting parameters and simplifies the numerical control programming operation. The results show that the reuse times of cutting parameters are more than 8000 times, effectively ensuring the machining efficiency and quality consistency of products.

Functionally Graded Additive Manufacturing: Bridging the Gap between Design and Material Extrusion

Nowadays, the use of 3D printing is becoming a key process for on-demand and customized manufacturing. One of the most flexible 3D printing techniques is fused deposition modeling (FDM), where the combination of multiple materials was recently introduced. A quantum leap in part design is possible by integrating local variations between materials that allow for expanded functionality to be built into a single part. Therefore, the process of co-extrusion and material mixing is becoming more and more popular. The process of management and design of the engineered part are still complicated, and there are no commercially available tools that follow the process from design to production of these highly engineered products. This paper proposes a methodology to fill this gap and allow any designer to be able to produce multi-material parts by editing a G-code (computer numerical control programming language) with engineered gradients for FDM technology. More specifically, the proposed approach is based on the modification of the G-code according to a volumetric model describing the local combination of two or more materials. This original aspect allows for a wide extension of the current software capabilities. To explain and test the method, a simple test case was investigated, in which two components of an earphone are consolidated and developed gradually by combining polylactic acid and thermoplastic polyurethane. The results show the effectiveness of the proposed approach within the limits of the material coextrusion additive manufacturing process.

Effect of Optimization Software on Part Shape Accuracy and Production Times during Rough Milling of Aluminum Alloy

Reducing production costs during machining processes can be implemented in several ways, including various methods of cutting parameters optimization. The aim of the described research was to evaluate the effectiveness of software that optimizes the NC (Numerical Control) code generated from a CAM (Computer Aided Manufacturing) system. The experiments were carried out in rough milling. For the experiment, a sample with five pockets was designed and fabricated using the original NC programs from the CAM system and optimized NC programs. Evaluated criteria were the impact on the accuracy of the produced surfaces and degree of production time savings. When using the optimization software, despite more intensive cutting conditions, deviations on the side surfaces of the pockets were reduced from 3 to 23%. On the horizontal surfaces, for two pockets, there was an increase in deviations of a maximum of 7.8%, and for the remaining three pockets, there was a decrease in deviations ranging from 8.3 to 36%. The optimized NC programs achieved time savings ranging from 12.8 to 15.9%. This knowledge is important for manufacturers, as it allows shortening production times and thereby reducing related costs.

Research on intelligent decision method of computer-aided manufacturing numerical control parameters based on model-based definition and back propagation neural networks

Aiming at the low efficiency and intelligence degree in the parameter setting of computer-aided manufacturing (CAM) numerical control (NC) programming caused by manual work, an intelligent decision-making method of CAM NC programming parameters based on model-based definition (MBD) is proposed. The hierarchical process model uses MBD technology to express the process flow and manage the process information. The tightness between process and NC machining is enhanced by sorting out NC machining steps and extracting their process information automatically. Then a back propagation (BP) neural network is used to mine the experience of NC programming in historical cases. Sparrow search algorithm (SSA) and other methods are used to optimize BP neural network’s initial weight and threshold, learning rate, and feedback process. A CAM parameter decision model based on BP neural network is constructed. Taking the connecting rod of a certain type of diesel engine as the experimental object, the method increases programming efficiency by 47%, with an accuracy rate of 80%. It is proved that the intelligent decision-making method proposed in this paper has practicability and feasibility.

Error estimation and cross-coupled control based on a novel tool pose representation method of a five-axis hybrid machine tool

Five-axis hybrid machine tools combine the advantages of series and parallel mechanisms; however, the time-varying, non-linear, and strong coupled characteristics of parallel mechanisms cause contour control difficulties, particularly during high-speed motion. To solve this problem, this study explores the error-transfer laws between the five feed axes, tool centre position (TCP), and tool orientation (TO). It proposes a new tool-pose representation method, called ‘TP’, for five-axis machine tools; and designs a cross-coupled controller taking TP as the control target. Moreover, a kinematic model of the hybrid machine tool is established, and the error transfer law is solved through the first-order differentiation of the kinematic model. Subsequently, two points are taken on the tool axis, the redundancy of coordinates is removed by coordinate transformation, and TP is achieved. Finally, a cross-coupled controller is designed. The input of the controller are the tracking errors obtained according to the five feed-axes commands and encoder feedbacks. In the controller, according to the laws of error transfer, the TP contour error is estimated in real time, and the control variables are assigned to the feed axes. Finally, taking a five-axis hybrid machine tool as an example, the error transfer characteristic analysis as well as error estimation and cross-coupled control (CCC) experiments are performed. The experimental results obtained through the numerical control (NC) program feedback of the computer numerical control (CNC) system verify the correctness of the theory and validity of the method.

Design and manufacturing of graded density components by material extrusion technologies

Innovative design methods and manufacturing technologies, such as lattice structures optimization and additive manufacturing, allow for the production of functional and extremely complex components. Recent literature shows limits in geometric modeling and data exchange, highlighting some improvements in the design of variable density lattice structures mainly for powder bed fusion technologies. Similar improvements are not available for material extrusion (MEX) technologies which show technological and numerical limits related to the computer numerical control programming language (G-code) generated by computer aided manufacturing (CAM) software. This work aims at overcoming the limits in fabricating graded density shell-based lattice structures for MEX technology by using the infill patterns available in the CAM software and editing the G-code based on a density map defined by volumetric models. Combining two usually separated phases, i.e., the geometric modeling and the CAM processing, several advantages are obtained, considering at the same time some of the technological constraints.The proposed approach is tested on a cubic sample and on a bracket fabricated by a fused filament fabrication technology. The results show that the method allows for the reduction of design efforts, amount of data exchanged, and processing time, obtaining an effective G-code and consistent components.

DEVELOPMENT OF ALGORITHMIC SUPPORT FOR PRACTICAL IMPLEMENTATION OF TESTING AND DIAGNOSTIC COMPLEX OF CNC MACHINES

CNC machines, including multi-purpose machines (product processing centers), have been widely used in connection with the creation of flexible production systems and significant progress in developing and improving the reliability of multi-purpose freely programmable, multiprocessor and small numerical program control devices (CNC) , so the development of algorithmic software for the practical implementation of the test and diagnostic complex and the use of diagnostic systems as a means of automation of information technology is one of the general directions of improving the efficiency of machine-building enterprises. However, in order to make decisions about the scope, stages and feasibility of using a particular diagnostic system for the selected object of study at a particular enterprise, it is necessary to assess its expected benefits. The use of diagnostics during operation of the machine imposes its influence on the means and methods of diagnosis, which should be convenient for use in the factory, to ensure the diagnosis process in the shortest time, to have reliable readings, especially with high requirements for product reliability. and in some cases without disrupting the mechanism, to be economically feasible. The design of the machine is adapted to the needs of diagnostics and must: have built-in devices that evaluate its parameters (pressure in the hydraulic system, temperature of energy-intensive units, accuracy of machining, speed); periodically connect to special equipment that will diagnose the basic parameters of the machine and provide data on its condition. The parameters of the technical condition (diagnostic features), which can be judged on the OD and which are diagnosed during operation of the machine, are: machine parameters that directly characterize its efficiency; damage and defects that occur during operation and lead or may lead to failure; side effects that are functionally or stochastically related to the initial parameters.

Solution of logical problem of numerical program control using the software-implemented

The article covers the requirements for software-implemented logic controllers, analyzes the functionality of the controller with construction of the functional model. The given practical example of Soft PLC controller application in frame of the CNC system shows the advantages of considered approach to design of electrics control systems.