scholarly journals Selecting the Safest CNC Machining Workshop Using AHP and TOPSIS Approaches

Safety ◽  
2021 ◽  
Vol 7 (2) ◽  
pp. 27
Author(s):  
Lucian-Ionel Cioca ◽  
Radu-Eugen Breaz ◽  
Sever-Gabriel Racz
Keyword(s):  
Machine Tools ◽  
Evaluation Criteria ◽  
Cnc Machining ◽  
Cnc Machine Tools ◽  
Cnc Machine ◽  
Analytic Hierarchy ◽  
Safety Issues ◽  
Computer Numerically Controlled ◽  
Machining Operations ◽  
Hierarchy Process

Machining operations on computer numerically controlled (CNC) machine tools are essential for the machining industry. Most of these operations take place in machining workshops. Safety issues in machining workshops shops can affect not only the health of the operators, which is extremely important, but also the productivity of the process and the accuracy of the parts. The research presented in this article addresses the issue of evaluating the safety of a CNC machining workshop, using a combined approach based on the analytic hierarchy process (AHP) and technique for order performance by similarity to ideal solution (TOPSIS) methods. A set of four evaluation criteria was proposed and the methods of processing the information for each criterion were used to extract the significant data needed for the evaluation. The proposed method was used to select the safest CNC machining workshop out of a total of three considered for assessment.

scholarly journals Evaluating Safety Systems for Machine Tools with Computer Numerical Control using Analytic Hierarchy Process

Safety ◽  
2019 ◽  
Vol 5 (1) ◽  
pp. 14 ◽  
Author(s):  
Sever-Gabriel Racz ◽  
Radu-Eugen Breaz ◽  
Lucian-Ionel Cioca
Keyword(s):  
Analytic Hierarchy Process ◽  
Machine Tools ◽  
Computer Numerical Control ◽  
Numerical Control ◽  
Machining Process ◽  
Cnc Machine Tools ◽  
Cnc Machine ◽  
Analytic Hierarchy ◽  
Safety Systems ◽  
Hierarchy Process

Computer numerical control (CNC) machine tools are complex production systems with fully automatic machine parts. Nowadays, high feed rates and machining speeds are used during the machining process. Human operators are still needed to set-up the machine, load/unload workpieces and parts, load the machining code, and supervise the machining process. The operators work in an environment where automated high-speed motions occur, and consequently, CNC machine tools have to be equipped with safety systems. The approach presented in this paper was to evaluate the main safety systems of CNC machine tools based upon the analytic hierarchy process (AHP). The analyzed systems were divided into six main categories and compared pairwise using five criteria proposed by the authors. The approach and the obtained results significantly relied upon the situation found at the industrial company used as a benchmark for the research. The analysis reveals that, among considered safety devices, manually operated controls are the most efficient ones. Finally, a sensitivity analysis was conducted to test the stability of the AHP solution.

scholarly journals Deflection Error Prediction and Minimization in 5-Axis Milling Operations of Thin-Walled Impeller Blades

2020 ◽  
Author(s):  
Mohsen Soori ◽  
Mohammed Asmael
Keyword(s):  
Machine Tools ◽  
Turbine Blades ◽  
Cnc Machining ◽  
Cnc Machine Tools ◽  
Machining Parameters ◽  
Cnc Machine ◽  
Virtual Machining ◽  
Machining System ◽  
Thin Walled ◽  
Machining Operations

Abstract To enhance accuracy as well as efficiency in process of machining operations, the virtual machining systems are developed. Free from surfaces of sophisticated parts such as turbine blades, airfoils, impellers, and aircraft components are produced by using the 5-axis CNC machine tools which can be analyzed and developed by using virtual machining systems. The machining operations of thin walled structures such as impeller blades are with deflection errors due to cutting forces and cutting temperatures. The flexibility of thin walled impeller blades can cause machining defects such as overcut or undercut. So, the desired accuracy in the machined impeller blades can be achieved by decreasing the deflection error in the machining operations. To minimize the deflection of machined impeller blades, optimized machining parameters can be obtained. An application of virtual machining system in predicting and minimizing the deflection errors of 5-Axis CNC machining operations of impeller blades is presented in the study to increase accuracy and efficiency in process of part production. The finite element analysis is applied to obtain the deflection error in machined impeller blades. In order to minimize the deflection error of impeller blades in the machining operations, the optimization methodology based on the Genetic algorithm is applied. The impeller is machined by using the 5-axis CNC machine tool in order to validate the developed virtual machining system in the study. Then, the machined impeller is measured by using the CMM machines to obtain the deflection error. As a result, the deflection error of in machining operations of impeller by using 5-Axis CNC machine tools can be decreased in order to enhance accuracy and efficiency of part manufacturing.

scholarly journals HYBRID ADDITIVE AND SUBTRACTIVE MANUFACTURING PROCESSES AND SYSTEMS: A REVIEW

2018 ◽  
Vol 18 (4) ◽  
pp. 5-24 ◽  
Author(s):  
Wit GRZESIK
Keyword(s):  
Machine Tools ◽  
Review Paper ◽  
Cnc Machining ◽  
Cnc Machine Tools ◽  
Manufacturing Processes ◽  
Laser Metal Deposition ◽  
Cnc Machine ◽  
Subtractive Manufacturing ◽  
Hybrid Platform ◽  
Machining Operations

This review paper highlights the hybrid manufacturing processes which integrate the additive and subtractive processes performing on one hybrid platform consisting of the LMD (laser metal deposition) unit and CNC machine tools. In particular, some important rules and advantages as well as technological potentials of the integration of different AM technique and finishing CNC machining operations are discussed and overviewed. Some representative examples such as formation of difficult features around the part periphery, deposition of functional layers and coatings and repair of high-value parts in aerospace industry are provided. Some conclusions and future trends in the implementation of hybrid processes are outlined.

CNC Machine Tools

2009 ◽  
pp. 165-187 ◽  
Author(s):  
Xun Xu
Keyword(s):  
Machine Tool ◽  
Machine Tools ◽  
Manufacturing Industry ◽  
Human Action ◽  
Cnc Machining ◽  
Cnc Machine Tools ◽  
Cnc Machine Tool ◽  
Cnc Machine ◽  
Cnc Machines ◽  
Time Required

The introduction of CNC machines has radically changed the manufacturing industry. Curves are as easy to cut as straight lines, complex 3-D structures are relatively easy to produce, and the number of machining steps that required human action has dramatically reduced. With the increased automation of manufacturing processes with CNC machining, considerable improvements in consistency and quality can be achieved. CNC automation reduced the frequency of errors and provided CNC operators with time to perform additional tasks. CNC automation also allows for more flexibility in the way parts are held in the manufacturing process and the time required to change the machine to produce different components. In a production environment, a series of CNC machines may be combined into one station, commonly called a “cell”, to progressively machine a part requiring several operations. CNC controller is the “brain” of a CNC machine, whereas the physical configuration of the machine tool is the “skeleton”. A thorough understanding of the physical configuration of a machine tool is always a priority for a CNC programmer as well as the CNC machine tool manufacturers. This chapter starts with a historical perspective of CNC machine tools. Two typical types of CNC machine tools (i.e. vertical and horizontal machining centres) are first discussed. Tooling systems for a CNC machine tool are integral part of a CNC system and are therefore elaborated. Also discussed are the four principal elements of a CNC machine tool. They are machine base, machine spindle, spindle drive, and slide drive. What letter should be assigned to a linear or rotary axis and what if a machine tool has two sets of linear axes? These questions are answered later in the chapter. In order for readers to better comprehend the axis and motion designations, a number of machine tool schematics are given.

Volumetric Positioning Errors of CNC Machining Tools and Laser Sequential Step Diagonal Measurement

2006 ◽  
Vol 315-316 ◽  
pp. 98-102 ◽  
Author(s):  
J.H. Shen ◽  
H.T. Zhang ◽  
Hong Tao Cao ◽  
Jian Guo Yang ◽  
C. Wang
Keyword(s):  
Machine Tools ◽  
Measurement Method ◽  
Measurement Data ◽  
Cnc Machining ◽  
Cnc Machine Tools ◽  
Cnc Machine ◽  
Transformation Matrices ◽  
Positioning Errors ◽  
Analysis Measurement ◽  
Key Factor

The volumetric positioning precision of CNC machine tools is the key factor to get high machining precision, so the analysis, measurement and compensation of the volumetric error is becoming more and more important. In this paper, the modeling results of 3-axes CNC machine tools with four different configurations are given based on rigid body theory and homogeneous coordination transformation matrices. An improved sequential step diagonal measurement method is proposed and analyzed because the current laser measurement methods are complex and time cost. At the final section of the paper, the measurement data was applied into the error compensation and the sequential step diagonal measurement method was validated efficient and convenient.

A unified manufacturing resource model for representation of computerized numerically controlled machine tools

2009 ◽  
Vol 223 (5) ◽  
pp. 463-483 ◽  
Author(s):  
P Vichare ◽  
A Nassehi ◽  
S Newman
Keyword(s):  
Machine Tool ◽  
Machine Tools ◽  
Manufacturing System ◽  
Cutting Tools ◽  
Cnc Machining ◽  
Cnc Machine Tools ◽  
Cnc Machine ◽  
Resource Model ◽  
Machining System ◽  
Manufacturing Resource

The capability of any manufacturing system primarily depends on its available machine tools. Thus machine tool representation is a vital part of modelling any manufacturing system. With the rapid advances in computerized numerically controlled (CNC) machines, machine tool representation has become a more challenging task than ever before. Today's CNC machine tools are more than just automated manufacturing machines, as they can be considered multi-purpose, multi-tasking, and hybrid machining centres. This paper presents a versatile methodology for representing such state-of-the-art CNC machining system resources. A machine tool model is a conceptual representation of the real machine tool and provides a logical framework for representing its functionality in the manufacturing system. There are several commercial modelling tools available in the market for modelling machine tools. However, there is no common methodology among them to represent the wide diversity of machine tool configurations. These modelling tools are either machine vendor specific or limited in their scope to represent machine tool capability. In addition, the current information models of STEP-NC, namely ISO 14649, can only describe machining operations, technologies, cutting tools, and product geometries. However, they do not support the representation of machine tools. The proposed unified manufacturing resource model (UMRM) has a data model which can fill this gap by providing machine specific data in the form of an EXPRESS schema and act as a complementary part to the STEP-NC standard to represent various machine tools in a standardized form. UMRM is flexible enough to represent any type of CNC machining centre. This machine tool representation can be utilized to represent machine tool functionality and consequential process capabilities for allocating resources for process planning and machining.

An Application of Shape Grammars to Planning for CNC Machining

2009 ◽  
Author(s):  
Christoph Ertelt ◽  
Kristina Shea
Keyword(s):  
Machine Tools ◽  
Spatial Relations ◽  
Cnc Machining ◽  
Numerical Control ◽  
Cnc Machine Tools ◽  
Basic Rule ◽  
Shape Grammars ◽  
Line Planning ◽  
Part Geometry ◽  
Machining Operations

Planning for Computerized Numerical Control (CNC) fabrication requires generation of process plans for the fabrication of parts that can be executed on CNC enabled machine tools. To create such plans, a large amount of domain specific knowledge is required to map the desired geometry of a part to a manufacturing process, thus decomposing design information into a set of feasible machining operations. Approaches to automate this planning process still rely heavily on human capabilities, such as planning and reasoning about geometry in relation to machining capabilities. In this paper, the authors present a new, shape grammar-based approach for automatically creating fabrication plans for CNC machining from a given part geometry. To avoid the use of static feature sets and their pre-defined mappings to machining operations, the method encodes knowledge of fundamental machine capabilities. A method for generating a vocabulary of removal volume shapes based on the available tool set and machine tool motions is defined in combination with a basic rule set for shape removal covering tool motion, removal volume calculation and CNC code generation. The use of shape grammars as a formalism enables systematic formulation of hard and soft constraints on spatial relations between the volume to be removed and the removal volume shape for a machining operation. The method is validated using an example of machining a simple part on a milling machine. Overall, the approach and method presented is an enabler for the creation of an autonomous fabrication system and CNC machine tools that are able to reason about part geometry in relation to available capabilities and carry out on-line planning for CNC fabrication.

Research on Machining Method of Complex Surface Face Gears

2012 ◽  
Vol 163 ◽  
pp. 233-237
Author(s):  
Yan Zhong Wang ◽  
Liang Wei Hou ◽  
Yan Qiang Liu ◽  
Rong Shen ◽  
Can Hui Wu ◽  
...  
Keyword(s):  
Machine Tools ◽  
Surface Characteristics ◽  
Complex Surface ◽  
Transformation Process ◽  
Cnc Machining ◽  
Cnc Machine Tools ◽  
Cnc Machine ◽  
Face Gear ◽  
Five Axes ◽  
Complex Parts

This paper describes the machining method of complex surface face gear used CNC machine tools and hob cutter, Based on surface characteristics and gear hob principle. A coordinate transformation process is explained in detail in the five axes CNC machining of complex parts. A CNC hob method is proposed about surface orthogonal gear. An experiment is done for validating the method.

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