Computer Numerical Control Programming Research Articles

Block processing time-based programming for high-speed, high-precision 5-axis machining

For high-speed and high-precision machining with orthogonal 3-axis minute line segment commands, a program should be generated by appropriately reducing the chord error (tolerance) or the block length (line segment length) based on the computer numerical control (CNC) block processing time Tb. The block processing time Tb is the duration from when the CNC decodes one block command in a program until when it controls the motors, depending on the processing power of the CNC. Accordingly, even in simultaneous 5-axis machining, it is necessary to research whether programs generated based on Tb can achieve high-speed and high-precision machining. Therefore, this study aims to realize simultaneous 5-axis machining at higher speed and precision using CNC programs with minute line segment commands based on Tb. In addition, we propose a more general identification method compared with that used in previous studies to identify Tb. Simultaneous 5-axis programs include two cases of control, namely, tool center point (TCP) control and Non-TCP control, and Tb was identified for both controls. For the machining method, using the block length based on Tb, we generated programs to machine the upper flat surface of a workpiece using simultaneous 5-axis machining while rotating the two rotary axes using a ball-end mill. We machined the workpiece and evaluated the machining speed and precision of the machined surface. We showed that simultaneous 5-axis machining with higher speed and precision can be achieved using programs based on Tb. In addition, we analyzed and considered the reasons for the higher-speed and higher-precision machining.

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.

A framework for practically effective creation of postprocessors for 5-axis CNC machines with all possible configurations and working mechanisms

The 5-axis CNC (Computer Numerical Control) machining plays an important role in manufacturing, especially in making parts of complex shapes such as turbine or propeller blades. However, there are always challenges of generating 5-axis CNC machining programs when working with different 5-axis CNC machines of various structures; and 5-axis CNC programs must be automatically generated by CNC postprocessors which calculate the inverse kinematics and convert the Cutter Location data to the CNC programs that are used for operating 5-axis CNC machines. Since the family of 5-axis CNC machines has a wide spectrum of machine configurations, with hundreds of mechanisms of 5 degrees of freedom, it is therefore practically challenging for engineers and CNC machine operators to create CNC postprocessors for specific 5-axis CNC machines. It is more challenging to create CNC postprocessors if engineers or CNC operators do not have strong backgrounds and professional skills in mathematical modeling and kinematics of machines. This paper presents a universal and intuitive framework and practical guidance to create CNC postprocessors for all 5-axis CNC machines, with the focus on a novel mathematical formulation of inverse kinematics of three main groups of 5-axis CNC machines. The case studies of creating CNC postprocessors with the commercially available 5-axis CNC machines were successfully demonstrated, in which the simulation scenarios and experiments were implemented to verify the created CNC postprocessors. The proposed frameworks and guides for generating CNC postprocessors can be conveniently and effectively applied in industrial practices, without the required strong backgrounds and skills for engineers or CNC operators in mathematical modeling and kinematics of machines, especially mathematical modeling of multibody systems.

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.

Project-Based Teaching of a Manufacturing Class During the COVID-19 Pandemic

Abstract The plastics engineering program at the University of Massachusetts Lowell has taught mold design and engineering to undergraduate students for over 60 years. In 2020, the unexpected arrival of the COVID-19 pandemic in March forced the instructors to revisit the class program and objectives. Similar to other academic courses, the class became virtual. This meant redesigning an intensive hands-on manufacturing class into one that could be taught and taken from our home offices while maintaining academic rigor and continuing to meet critical student learning objectives. The timing of the pandemic meant that students, who were completing tooling split designs and starting computer numerical control programming, could not move forward with machining, assembly, and molding. Instead, their projects became virtual learning experiences. This paper provides the analysis and discussion of how new ideas in teaching were implemented to virtually introduce engineering students to the world of plastic manufacturing. The students' work was carried out on plastic part designs of their choice, some of which included thin walls (<2 mm) and microscale features (∼800 μm) typical of a micro-injection molding process.

Development of instructional materials based on mobile learning media (MLM) and its benefits

This study aims to develop a learning model based on Mobile Learning Media (MLM), test its effectiveness, and describe its benefits. MLM was developed for Computer Numerical Control (CNC) programming courses in vocational high schools. The effectiveness is tested by indicators of students’ higher-order thinking skills (HOTS). Advantages are explored based on their performance in learning. Recently, CNC programming lesson is known as a difficult subject because it requires critical and creative thinking skills. The research design was experimental with a pretest-posttest random control group pattern. Research respondents totaled 120 students with 60 students in the experimental class and 60 students in the control class. The research data includes data on the effectiveness of the model and student learning outcomes. Analysis of research data used descriptive statistical techniques and independent sample T-test with the help of SPSS 2.0 software. The results showed that the use of MLM was effective to improve teacher performance in teaching. MLM can facilitate students to develop HOTS. This is proved by the increase in student learning outcomes after the application of MLM. Based on the analysis of answers accompanied by reasons, students are able to show significant improvement in all critical and creative thinking processes.

CNC PROGRAM AND PROGRAMMING OF CNC MACHINE

A programming to make parts are CNC Programming (Computer Numerical Control Programming) for machines. An NC program consists of a sequence of instructions that control the motion and automatic sequences of an NC Machine to perform a particular processing task. In a general sense, the term NC programming refers to the creation of control data for machining workpieces on NC and CNC machines. NC programming has a decisive influence on the cost-effectiveness and profitability of NC manufacturing. The selection of a programming system is mostly guided by the need for software that is suitable for the application at hand, readily available, and as universally applicable as possible.

Improvement of CNC Lathe Performances by Tungsten-Carbide Tool Using Desirability Function Analysis for Fabrication of Miniature Component

Computer numerical control (CNC) machine has greater utility in the modern advanced industrial field. This paper deals with the parametric effects such as spindle speed (1500-2100 rpm) (N) (X1), depth of cut (DOC) (0.15-0.55 mm) (X2) and feed rate (f) (30-50 mm/min) (X3) on machining characteristics like tool wear rate (TWR) and surface roughness (Ra) during fabrication of IS-617 Aluminum miniature component by advanced CNC lathe using Tungsten-carbide tool. The article analyzes the second-order mathematical model development with co-relation of co-efficient of regression (COR) and analysis of variances (ANOVA) using desirability function analysis during the production of the miniature segment. The paper also consists of multi-criteria optimization for achieving the optimal parametric combination for minimum surface roughness and tool wear rate for this manufacturing operation. The paper also shows the fabricated micro-product of Aluminum at the optimal parametric conditions using CNC programming. It is found that spindle speed has a greater effect on the tool wear rate and depth of cut has dominating effects on surface roughness of job specimen. Desirability parametric combination for minimized surface roughness as well as tool wear rate has been found 1523 rpm/0.15mm/30mmmin-1.

On the new Algorithm for Solving Continuous Cutting Problem

The problem of tool path optimization for CNC (Computer Numerical Control) thermal cutting machines as well as its classification are considered. A new approach to solving Continuous Cutting Problem is proposed based on local optimization using Fermat principle and Variable Neighborhood Search approach, which automatically takes Precedence Constraint into account, that is crucial for generating correct CNC programs due to technological features of modern CNC cutting equipment.

A General G-Code Algorithm for Deep Hole Drilling

AbstractHole drilling is the most common machining operation performed on computer numerical control (CNC) machine tools or machining workshops. Drilling appears to be a relatively simple process however; when it involves drilling deep holes, it becomes one of the most complicated metal cutting processes. Although modern machine tool controllers are equipped with special drilling canned cycles, these cycles have significant constraints mainly due to their limited framework of application. The present work proposes a general G-code algorithm intended to accommodate effective deep hole drilling. The algorithm is characterized by flexibility in the pecking strategy and adaptability to the needs of each individual drilling case. The development of the proposed algorithm is based on parametric programming which is a powerful CNC programming technique.

A generic and theoretical approach to programming and post-processing for hypoid gear machining on multi-axis CNC face-milling machines

Hypoid gears are machined on multi-axis computer numerical control (CNC) face-milling machines, and parameters of a cutter system and machine settings are calculated for a specific gear design. The existing hypoid gear machining methods use a simplified blade model of cutting systems, resulting in large errors in the machined gears. Moreover, special CAD/CAM software programs are used to design and calculate the machine settings of hypoid gears. These software programs are developed by the OEMs for particular machine tools, and it cannot be used for hypoid gear machine tools of different sizes and configurations. To solve these problems, this research proposes a generic approach to CNC programming and post-processing for gear face milling, considering the accurate blade model in the cutter system. The main contributions of this part include (1) a new mathematical model to calculate the cutter system location and orientation and (2) a generic post-processing method to establish the machine kinematics chain and to compute the coordinates of the machine axes for the face-milling process. This approach provides a general and accurate methodology for the face milling of hypoid gears on machine tools of varying configurations and can be directly applied to the hypoid gear manufacturing for better quality.

Intelligent manufacturing system of impeller for computer numerical control (CNC) programming based on KBE

To solve the problem of advanced digital manufacturing technology in the practical application, a knowledge engineering technology was introduced into the computer numerical control (CNC) programming. The knowledge acquisition, knowledge representation and reasoning used in CNC programming were researched. The CNC programming system functional architecture of impeller parts based on knowledge based engineering (KBE) was constructed. The structural model of the general knowledge-based system (KBS) was also constructed. The KBS of CNC programming system was established through synthesizing database technology and knowledge base theory. And in the context of corporate needs, based on the knowledge-driven manufacturing platform (i.e. UG CAD/CAM), VC++6.0 and UG/Open, the KBS and UG CAD/CAM were integrated seamlessly and the intelligent CNC programming KBE system for the impeller parts was developed by integrating KBE and UG CAD/CAM system. A method to establish standard process templates was proposed, so as to develop the intelligent CNC programming system in which CNC machining process and process parameters were standardized by using this KBE system. For the impeller parts processing, the method applied in the development of the prototype system is proven to be viable, feasible and practical.

Simulation and verification of parametric numerical control programs using a virtual machine tool

A parametric computer numerical control (CNC) program was developed to make a test complex surface on a vertical milling machine equipped with an external fourth rotational axis. Parametric programming was used in order to get higher flexibility of the manufacturing process. The ball-end milling process was simulated and verified in a virtual model of the machine tool developed with the module integrated simulation and verification of the product lifecycle management software of Siemens NX7®. After that, the real process was carried out on the shop floor to machine the test surface. This demonstrates that the virtual machine tools are an effective resource to simulate and verify the performance of machining processes controlled by CNC parametric programs. The possibility of accurately simulating the parametric CNC program reduces the risk of its implementation and enables a more frequent use of this efficient feature of contemporary CNC machine tools.

Numerical control machining simulation: a comprehensive survey

Since the first numerical control (NC) machine tool was created at Massachusetts Institute of Technology in the 1950s, productivity and quality of machined parts have been increased through using NC and later computer numerical control (CNC) machine tools. Like other computer programs, errors may occur in a CNC program, which may lead to scraps or even accidents. Therefore, NC programs need to be verified before actual machining commences. Computer-based NC machining simulation is an economic and safe verification method. So far, much research effort concerning NC machining simulation has been made. This paper aims to provide a comprehensive review of such research work and a clear understanding of the direction in the field. First, the definition, common errors, programming approaches and verification methods of NC programs are introduced. Then, the definitions of geometric and physical NC machining simulation are presented. Four categories of NC machining simulation methods are discussed. They are solid-based, object space-based, image space-based and Web-based NC machining simulations. Finally, future trends and concluding remarks are presented.

An Integrated Methodology for the Teaching of Computer Aided Tools for Automated Machining

To date a wide variety of computer aided tools are available for computer numerical controlled (CNC) automated machine-tools. Solid modelling software and 3D computer-aided design (CAD) are know firmly established in the early design stage whereas computer aided machining (CAM) and computer numerical control (CNC) simulator software is employed during the manufacturing stage. Training in the use of these systems is often undertaken in separate technical disciplines and training courses (e.g., graphic representation, mechanical design, computer numerical control programming, computer-aided machining, manufacturing technology, etc.), but students often lack a sound global understanding of these tools and fail to comprehend the full potential of integrating these applications. Thus, the aim is to propose a global methodology for the teaching of computer aided automated machining systems by integrating an array of computer aided tools (3D solid modelling, CAD/CAM software, CNC simulators, DNC communication, etc.) in order to enhance knowledge and develop skills of the entire manufacturing process i.e., to provide practical hands-on tasks from the early design stages to the final stages of the computer aided automated machining of a product.

Development and evaluation of web service-based interactive and simulated learning environment for computer numerical control

Multimedia technology and Internet applications are important tools for teaching and learning in engineering education. Nowadays online simulative environments are indispensable tools for teaching computer numerical control (CNC) course in mechanical engineering. Nevertheless, past studies seldom designed CNC code or program error handling mechanisms, and failed to use new emergent technologies and applications. This study proposed a design for a WSISLE-CNC (web service-based interactive and simulated learning environment for CNC) based on Web service technology. A questionnaire survey from vocational school instructors and students revealed a high degree of enthusiasm for this proposed approach. In summary, the main contributions of this study to engineering education are: (1) development of several types of CNC code or program error handling mechanisms and applications, and (2) use of Web service concepts and technology to develop various kinds of CNC simulation services. © 2009 Wiley Periodicals, Inc. Comput Appl Eng Educ 18: 407–422, 2010; View this article online at wileyonlinelibrary.com; DOI 10.1002/cae.20147

Improving free form surface machining performance by ball end milling model

In CNC (computer numerical control) programs, cutting tool needs to move along a path described by a sequence of curves starting from the predefined Cutter Location (CL) points. In this article, cycle time is minimised and cutting forces are limited by a threshold for toolpath generation. In order to determine the cutting forces in each direction for all CL points a force map which overlapping with a uniform Cartesian mesh is constructed showing all possible cutting forces from each CL point to its neighbours. This map is obtained by pre-computation of force simulations in each direction. Force simulation of the newly developed paths and its experimental validation are obtained and compared. Moreover, forced-based feedrate scheduling strategy is utilised for the same free form surface to decrease cycle time. Feedrate is adjusted along toolpath to keep cutting forces at preset force value.

Intelligent process‐planning system or optimal CNC programming – a step towards complete automation of CNC programming

One of the bottle‐necks of computer numerical control (CNC) machining is the CNC programming. It relies on the experience and skills of the CNC programmer for the generation of the CNC program. The intelligent process‐planning system described in this paper generates a process plan automatically for CNC programming. It utilizes artificial intelligent technologies such as knowledge base, blackboard system and machine learning to extract machineable features, and proposes and selects optimal tools for the machining of the given part. Its flexibility and simplicity provide a convenient way to include new techniques and knowledge. The incorporation of this system with other CAD/CAM tools could effectively automate the CNC programming process.

A computerised minimum distance algorithm for machining of sculptured surfaces

This paper presents a unique minimum distance algorithm for machining of sculptured surfaces on computer numerical control (CNC) machines. The algorithm has been used to develop a system that graphically simulates the cutter path of the defined surfaces and generates the required CNC programs. The paper presents the experimental results of the surface roughness, tool size, and computed numerical control (NC) points for various tolerance values used on several sculptured surfaces designed by the system and actually machined on a CNC machining centre using the generated NC program from the system.

Simulation of CNC controller features in graphics-based programming

The arrival of microcomputers has led to the rapid development of the approach to Computer Numerical Control (CNC) programming. CNC programs can be generated by employing graphics instead of time consuming, lengthy programming statements. A graphics-based programming system has been developed. It enables the use of graphics for the CNC programming and improves CNC capability by permitting simulation. This paper shows that the capabilities of a basic controller can be enhanced by simulation of advanced controlling features in a microcomputer. The approach developed in this paper represents the current trend of increasing emphasis on microcomputer-based software systems for machining.