Applied Mechanics and Materials Vols. 220-223 (2012) pp 360-363 © (2012) Trans Tech Publications, Switzerland doi:10.4028/www.scientific.net/AMM.220-223.360
A framework for implementing RFID-based cutting tools management system in a machining workshop Peilu Sun1,a and Pingyu Jiang 1,b 1
State Key Laboratory for Manufacturing Systems Engineering, Xi’an Jiaotong University, Xi’an Shaanxi 710049, China a
[email protected],
[email protected]
Keywords: RFID (radio frequency Identification), cutting tools, tool management, framework
Abstract. As one kind of indispensable consuming resources, efficient cutting tools management plays an important role in increasing production capacity of machining workshop and ensuring the products quality. In this paper, a RFID-based cutting tools management system (CTMS) is proposed and its implementation framework is established. Furthermore, four key enabling technologies are addressed to investigate the real-time monitoring, dynamic scheduling, inventory alert and life prediction of cutting tools. Finally, a simple example is given to demonstrate the operation procedure of the established CTMS. Introduction With the development of modern machine-tool manufacturing industry, the functions and performances of machine tools have been greatly improved. Especially, the uses of new cutting tools have also enhanced the processing capacity of advanced machine tools. However, as one kind of indispensable consuming resources, the increasing demands of cutting tools in modern machining workshop lead to more complex management. Under this situation, the traditional cutting-tool management approach should be improved so as to meet the real-time and dynamic requirement of cutting tools. RFID technology has made tremendous achievements in the past few years, which has been widely applied in manufacturing field [1, 2], such as supply logistics and production logistics. Since cutting tools play a significant role in production process of machining workshop, applying RFID technology into cutting tools management has drawn much attention from scholars and practitioners. Cheng, etc. [3] discussed the application of RFID in cutting tool supply chain management, and Laure Vogel, etc. [4] developed and tested a RFID-based tracking application of cutting tools. Nevertheless, how do we effectively utilize RFID technology to collect the cutting tools information? Which factors and methods should be considered in the cutting tools management? How do we improve the efficiency of the cutting tool management in a machining workshop? All these above problems are still very difficult and there is no systemic research idea to address these problems in related literature. The goals of this paper are to establish a RFID-based cutting tools management system (CTMS) in a machining workshop and its implementation framework is proposed. The hardware configuration, data collecting and processing, the key enabling technologies and its application are also discussed. It is expected that the established CTMS could be used in the current and future advanced CNC machine tools in modern machining workshops so as to effectively improve the efficiency of cutting tools scheduling and reduce the machine downtime losses due to the unreasonable usage and scheduling of cutting tools. An implementation framework for RFID-based CTMS The basic idea of establishing a RFID-based CTMS is described here. Through adopting the RFID technology and network technology, the real-time status information of various cutting tools could be collected, which provides a basis for the comprehensive tracking management. Though taking full
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account of the interactive mechanism between the tool magazine of machine tools and the tool library of machining workshop, a smart matching and dynamic scheduling of cutting tools could be fulfilled so as to ultimately achieve the purpose of efficient management for cutting tools in machining workshop. From a systemic perspective, RFID-based CTMS should be divided into four levels as shown in Fig.1. Hardware supporting layer In order to effectively apply RFID in CTMS, the related supporting hardware should be configured. The electrical tags are attached to cutting tools or pallets; the RFID readers and antennas are installed around the tool magazine of machine tools and the tool library of machining workshop. In addition, computers and network equipment used to ensure the communication and monitoring between the various types of hardware are included. Data layer This layer explores the underlying database of the RFID-based CTMS. It mainly includes the static and dynamic information of cutting tools. The static data refers to the machining types, suppliers and tool life, etc. The dynamic data refers to the real-time status, and accumulated working time, etc. System modules layer This layer explores the different modules of the RFID-based CTMS. Specifically, the EPC encoding, RFID configuration, real-time monitoring, static and dynamic scheduling, inventory, tool life prediction and evaluation, the machining time measurements are considered. In addition, the relationships among different modules are also demonstrated. Application layer This layer explores the applications of the RFID-based CTMS by means of enabling the modules layer, which is the top level of the overall structure of the RFID-based CTMS. It provides an interactive interface between users and various devices. The state monitoring, dynamic scheduling, inventory management and life prediction of cutting tools are included.
Fig.1 The layer relationship of the established RFID-based CTMS Key Enabling Technology In order to implement the above framework, four key enabling technologies are proposed in this paper. The key enabling technologies of the RFID-based CTMS are shown in Fig.2.
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The location and state monitoring of cutting tools. It can effectively monitor the running status and operational location of cutting tools, and can avoid the tool misuse as much as possible. Tool inventory management. It can always ensure that the tool can meet the demands of the current processing, and be able to minimize the tool storage costs. The prediction and management of tool life. It can both maximize the usage of cutting tools, and also avoid the potential tool broken and the out-of-tolerance of parts caused by using the cutting tools beyond their normal life. The dynamic scheduling of cutting tools. It can effectively improve the efficiency of the tool scheduling, reduce scheduling time, respond effectively to the occurrence of a variety of emergency situations and improve the overall processing efficiency of the machine tool.
Fig.2 The key enabling technologies of the RFID-based CTMS A simple description example In order to further clarify the running mechanism of established RFID-based CTMS, a simple example is shown in Fig.3. It mainly includes 5 steps. Step 1 Analysis of process information Tool intelligently matching
The information repository of tool life
Tool magazine of machine tool
Step 2 Static scheduling of cutters
Analyzing the remaining life of cutters
Workshop cutter library
Step 3 Machining on machine tool
Real-time monitoring & misusing checking of tool
The information repository of tool life
Step 4 Dynamic scheduling of cutters
Tool exception
Counting the usage of tools Assessing remaining life of tools
Step 5 The end of processing
Example Part
Fig.3 The flow chart of a simple example
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Step1: Analyzing the process information and matching the cutting tools intelligently. Through analyzing the process information of the given part, the process route and tool requirements are inputted into the established CTMS. Through adopting the intelligent matching algorithm, the appropriate cutting tools are selected. Step2: Static scheduling of cutting tools. Based on the above matched result of the cutting tools, the tool magazine information of machine tool and the tool life information are taken into account in the static scheduling so as to determine the cutting tools movement in the tool magazine and ensure the life of cutting tools. Step3: Machining and monitoring. According to the static scheduling result, the RFID devices are configured around the different nodes so as to identify the cutting tools states. And then, tool misuse situation is checked and this information is real-timely displayed on the electronic kanbans of the machine tools and machining workshop. Step4: Dynamic scheduling of cutting tools. When the exceptions of cutting tools are detected by RFID-based CTMS, a dynamic scheduling module is triggered and executed in order to reduce machine downtime losses caused by these exceptions. It is noted that this step would be skipped if there is no exception for cutting tools. Step5: Estimating the remaining life of cutting tools. After completing the machining tasks, its working time is calculated and remaining life is estimated. This information is pushed into the database and the tool life information is updated, which provides a basis for implementing the step1 and 2. Conclusion In this paper, a RFID-based CTMS is proposed, and its framework and enabling technologies are investigated. The following conclusions can be drawn. We can quickly set up a general idea of implementing the RFID-based CTMS, by which the main contents and the basic relationship of the various modules in the RFID-based CTMS can be organized easily. The framework is suitable for the cutting tool management of the CNC machining workshop that has both tool magazine of machine tool and tool library of workshop. Therefore the framework of RFID-based CTMS has better applicability. The applications of RFID in CTMS have greatly enhanced the scalability of the entire system. Through detailed designing, the RFID-based CTMS can tremendously improve the traditional tool management mode in machining workshop. Acknowledgements This work is supported by both National Key Projects for NC Equipments (2012ZX04010071) and National S&T Support Program in the 12th Five-Year Plan (2012BAH08F06). References [1] G.Q. Huang, Y.F. Zhang and P.Y. Jiang, Robotics and Computer-Integrated Manufacturing, Vol. 23 (2007), p. 469-477. [2] J. Brusey and D.C. McFarlane, International Journal of Computer Integrated Manufacturing, Vol. 22 (2009), p. 638-647. [3] C.Y. Cheng, D. Bartonb and V. Prabhua, International Journal of Production Research, Vol. 48 (2010), p. 1-19. [4] L.Vogel, B.S Prabhu, R. Gadh, Development and Testing of an RFID-based Cutting Tools Tracking Application. 2nd Hewlett Packard RFID Symposium (2007).
