Platform for Discrete Industry
Q.Y. Dai1, R.Y. Zhong2, K. Zhou1, and Z.Y. Jiang1
Faculty of Information Engineering, Guangdong University of Technology
daiqy@gdut.edu.cn, danilke@163.com, jiangzhenyong@yahoo.com.cn
2
Industry and Manufacturing System Engineering Department, HKU
zhongry@hku.hk
1
Abstract. Discrete industry (DI) concentrates on a class of business where the production process is basically no material change except the shape and compositions. In such DI workshop, productivity is greatly obstructed by tedious information transferring and management by paper work. This paper proposes a RFID-enabled real-time paperless hardware platform for DI. First, wireless manufacturing devices such as RFID readers are deployed in DI workshop. Then, a wireless communication network is set up. Finally, real-time manufacturing could be achieved according to the reorganization of production. A case study is also introduced in this paper to illustrate how real-time manufacturing works through this platform in DI workshop. Limitations such as channel seeking and universal work flows configuration should be improved if this platform of great merits to extend to other industry.
Keywords: RFID, Real-time Manufacturing, Hardware Platform, Discrete Industry.
1 Introduction
Discrete industry (DI) refers to produce products which are assembled from a variety of components (Florent 2001). With the necessary components and products identified by ratios, these materials could not be less or more. Great many manufacturing fields are belonged to DI, such as machinery manufacturing, automobile manufacturing, household electrical appliance manufacturing, etc. DI dose not follow the traditional personality, but also takes on the dynamic characteristics: planning → complex scheduling → processing → design changes → dynamic scheduling → feedback (Zhong et al 2008).
As one of the primary industry in China, DI follows such personalized features:
• DI productions are so complex that one component contains several assemblies with the fixed relations and structures according to different orders;
• DI enterprises produce series of products which are determined by source materials;
• DI processes contain several sub-process or parallel processes which are consist of complicated procedures that are most probably ambivalent or momentary
G. Huang et al. (Eds.): DET2009 Proceedings, AISC 66, pp. 1743–1750. springerlink.com © Springer-Verlag Berlin Heidelberg 2010
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changeable factors. In other words, it is more difficult to control the processes and quality tracking than in process manufacturing;
• The production capacity is not decided by the capacity of machines, but by several other vital aspects such as the material bulk, preparation time, logistics path, etc. One of the most dominant aspects is rationality and configurations about manufacture elements;
From the beginning of DI development in China, there are large quantities of crisis hidden in the flourish especially with the purchase of economic profits after more then 50 years. DI in China is confronted with acute challenge and disadvantages such as lag of real-time data collecting which causes the delaying of response to the market. What is more, information gaps and fire fighting are frequently occurred in the DI enterprises’ workshops in China.
This research involves a real-time manufacturing hardware platform which is mainly for the management of workshop in DI. The research question is “how we can design a hardware platform for the DI to capture real-time manufacturing and paperless factory?” And this paper takes a case study as an example to illustrate how to design and realize it in DI shop floors.
2 Literature Review
The key researches of DI recently are how to design a system or propose a methodology which could meet the complex environments in DI workshop (Kletti et al 2007). Some available methods are introduced by many a researchers. RFID technology is applied for efficient process control (Kim et al 2006, Modrak et al 2006). RFID becomes the hottest field which is paid much focus on as its brilliant performance in tracking. RFID-based Risk Management System (RRMS) with risk management concept to help monitor shop floor operations is also proposed by Poon (2007).
Then another research art is how to achieve real-time manufacturing which could help manufacturers to share information, streamline, optimize, and improve day-to-day plant operations (Katzel 2008). RFID is justified to be a good methodology to do that, especially in real-time manufacturing (Lu et al 2006, Huang et al 2008). Such implementation approach for the monitoring and analysis of a DI manufacturing environment using the RFID technology were presented in many fields. (Katariina et al 2006, Budak et al 2007, Ji et al 2008, Zhong et al 2008). And coordination mechanism of multi workshop manufacturing architecture of real-time manufacturing was applied to a particular industry (Huang 2008).
Although, some new methods have been proposed to set up the hardware platform and software structure using RFID, Bar Code, networks (Keskilammi et al 2003, LIU et al. 2007, Dai et al 2008), which would not propose efficient way to face some key and urgent points in DI, such as how to intercommunicate in DI shop floors, how to response as fast as possible when some emergencies occurred.
3 Real-Time Manufacturing DI Workshop
This real-time manufacturing DI shop floor is organized by Production Department, Quality Department, Machinery Department, Technology Department and Assistant
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Department. Production Department mainly manages order receiving and distributing, especially those emergency orders. Quality Department mainly deals with quality checking and quality issues such as raw-material quality issues, WIP quality problems such like those. Machinery Department focuses on the machine maintenances and repair. Technology Department concentrates on the engineering design and new product design, especially gets ride of the redone work design. Assistant Department main deals with some special processes such as those can not be completed in the shop floor/enterprise. Figure 1 illustrates the manufacturing infrastructure in the DI enterprise.
Despite the enterprise has set up SAP ERP, PDM, CAPP, etc enterprise information systems. These systems are incapable of controlling shop floor production. Inconstancy of plans and executions is one of the bottlenecks in the shop floor. As a result, paper work dominated each department and shop floor. Information gaps between each shop floor, paper missing, and manufacture delaying are frequently occurred in the enterprise. So, a real-time manufacturing platform is necessary for this enterprise.
4 Hardware Platform Design
4.1 RFID
RFID (Radio Frequency Identification) uses electromagnetic induction, and spreads signal between tags and readers. RFID is very qualified in real-time manufacturing platform because of its environmental adaptability, the ability of read and write, and its excellent advantages:
(1) small, non-contact, reusable; (2) security, anti-cloning;
(3) anti-pollution, flexible identification; (4) rewritten;
(5) multi-tag identification at the same time.
Using the features of RFID, which is the best available methodology improved the present management in the workshop, manufacturing fields have used this technology to tracking production and processes. Notwithstanding RFID has been used in large quantity of fields, real-time manufacturing workshop in DI has not been awaked as some intricate reasons such as magnetic interference, cost, oil pollution, etc.
And the other question should be solved next is “How to transfer information between RFID devices”. 433MHz wireless communication is introduced and very qualified for this platform, as its cost and simple user-defined protocol which is easy-going for the DI enterprise to implement. 4.2 433MHz Wireless Communication
433MHZ frequency belongs to international ISM frequency channel and suits for developing near-range wireless communication products. It is a very effective method to reduce/eliminate error-prone and tedious manual data processing activities and
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Fig. 1. DI workshop manufacturing infrastructure
discover bottleneck, diagnose process errors, adjust schedules for unexpected disturbances by 433MHz wireless network technology. In the proof-of-the-concept study, 433MHZ is applied in the hardware platform according to some basic reasons. Firstly, the cost should be acceptable by the enterprises. Second, transfer speed could be competent for the workshop data flows which are full of texts and figures. Finally it is the function range should cover all workshops or even cross them while BER could be controlled in a certain range.
Most of DM enterprises want to know how many people are working, when the tasks for each worker could be finished, whose duty is when quality issues occurred. According to those requirements, a hardware platform based on RFID and 433MHz is set up to deploy in workshops. The following table 1 provides the testing results obtained by using this wireless communication technology in one workshop. 4.3 Overview of Real-Time Manufacturing Hardware Platform
The real-time manufacturing hardware platform contains IDT (Intelligent Data Terminal), BS (Base Station), cable, PCI cards, WS (Work Station), UTP and server (Figure 2). There are three types of network could be used according to the workshop environment and wiring way, including RS485, TCP/IP and 433MHZ wireless communication. And two types of IDT have been developed, one is fixed one and the other is hand-held one, however they have the same function but the hand-held type is much more convenient especially for the warehouse holders and quality checkers.
A RFID-Enabled Real-Time Manufacturing Hardware Platform for Discrete Industry
Table 1. 433MHz wireless communication test results
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ITEMS RESULTS Furthest Range Number of Terminals Picture Download Time BER Resend Rate Packet Loss Rate
Keyboard Average Response Time
500m 60sets <5s <0.001 <0.01 <0.0001 <1s
Fig. 2. Real-time manufacturing hardware platform
The communication speed could reach 2400bps to 115200bps as the networks and the workshop environments after some basic configurations. The following figure shows the hardware platform which is set up in DI enterprise including workshops, office, and IT centres, where are deployed IDTs, WS and servers. After testing with the connection of each component such as computer and cable, cable and BS, PCI-1612 card of four or eight COMs is used for each WS depended on the channel deployed in the workshop.
4.3.1 Intelligent Data Terminal (IDT)
The mainly function of IDT is to input/output data and display some basic information which is deployed in the workshops. There are seven main components of IDT, which are showed in figure 3.
IDT had integrated primary components which RFID is one of the most vital one that could read tags and display information which is auxiliary for the production. Workers in DI workshop usually operate machines, which IDTs are located on or near as convenient as possible.
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Fig. 3. IDT components
Fig. 4. BS Components
4.3.2 Base Station
BS (Base Station), a bridge between WS and IDTs is the other hardware for communication between IDTs and computers, which is the mainly distributing and transferring device. It contains five main parts: network control, data process, memory, MCU, send/receive unit. The following figures shows the components of BS.
IDTs do communicate with BS through wireless communication method. Each IDT is controlled by WS located in the workshop office centrally, which connects with BS by PCI-1612 card and masked-cable. The BS occupies one frequency with the aim of interference with 50 KHz as bandwidth.
5 Case Study
This case study comes from one of our sponsors which locate in PRD (Pearl River Delta) in south of China. After all the IDTs and BSs are deployed in the shop floors, processes and logistics are totally controlled by the hardware platform. IDTs play crucial roles in those workshops such as display job instructions, machinery check, quality data handing, etc. With all the production and logistic information, material traceability, information visibility and real-time manufacturing and paperless factory can be achieved to form a closed-loop production control cycle.
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Fig. 5. Real-time manufacturing in DI workshops
The following figure shows how the real-time manufacturing platform in the DI shop floors works from start of orders to the end of products.
6 Conclusion and Remarks
This paper mainly discusses how to set a real-time manufacturing hardware platform for discrete industry (DI). After practical application, this hardware platform is competent for products tracking, quality monitoring, real-time data collecting, plan reasonable arranging, and equipment monitoring. This paper also illustrates the possibility of integration of RFID, 433MHz wireless communicating to solve DI workshop problems. This platform has been extended in the large-machinery assemble enterprises, glass manufacturing and mould fields, and even the engineering training centre with web version in high school, in where it accomplished excellent performance to the acquirements.
Two limitations should be improved since this hardware platform has great merits to promote. First, the IDTs can only be controlled by a particular BS with solid channel frequency. They can not seek the nearest BS for better communication. Second, universal configurations in this hardware platform are obstructed by complexity in DI workshop. The installation of this hardware platform should be supervised by professional guidance.
Acknowledgment
The authors thank to the nation R & D which gave partial finance support. Thanks to all members of project team, Faculty of Information Engineering the Guangdong
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University of Technology (China), Department of Industry & Manufacturing System Engineering the University of Hong Kong (China), especially the constructive guidance from great many experts and engineers. Finally thank you very much to Hitachi Elevator (China) Co.,Ltd., HUALJI AUTO-ACCESSORIES MFG CO.,LTD, KEDA INDUSTRIAL CO., LTD , Guangdong Greatoo Mould CO., LTD and Fuyao Group.
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