ADVANTAGES OF RFID FOR WARRANTY MANAGEMENT AND/OR MAINTENANCE

Transcription

1 ADVANTAGES OF RFID FOR WARRANTY MANAGEMENT AND/OR MAINTENANCE J.-D. Chatelain RFID RLS CONTRINEX AG Industrial Electronics Route André Piller 5 CH-762 Givisiez Switzerland Tel: Fax Internet: Contrinex 23 - JDC TUT_XF_Advantages of RFID 38

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3 ADVANTAGES OF RFID FOR WARRANTY MANAGEMENT AND/OR MAINTENANCE Overview Transponder Unlike to the barcodes, the information in the transponder can be modify. The transponders can be read or written, even if they are not visible. The transponder is resistant with respect to the environment. The transponders are protected against copy. The transponders will withstand time. RFID systems RFID system allows to avoid human error during introduction of data RFID system works like a distributed database (each transponder containing information) and can be part of a computer network. The data, in a RFID system, are secure. Description of the production plant Introduction In order to show the advantages of RFID, let us imagine schematically a company which produces reducing gears. Layout of the plant Stock Machining Packing Shipping Drying Surface treatment Reception Control Assembly Test Page

4 Course of the manufacturing process Operations in the stock area After reception, the raw material is stored in the stock. A RFID transponder (tag) is affixed to it. A lot of data can be entered in this transponder like: the supplier the date of reception the results of incoming inspection the dimensions and the weight of the raw material The raw material will be debited in slices as needed. Each time it is done, the new values of the parameters concerning the raw material will be written into the tag so that one have, at each moment, the status of the stock. Transponders (tags) Raw material The slices will be put into a carrier. On each carrier is affixed a transponder. As the carriers follow the pieces during the whole manufacturing process, a lot of information will be stored in the transponder. First of all, there are information like: data concerning the customer production order number information about the raw material (for traceability) Transponders (tags) Carriers Operations in the machining area In this area, the slices will be transformed to achieve their final shape. As an example, figure below shows schematically the different steps of machining for the central gear of the reducing gears. Slice Milling Drilling Gear cutting A specific machine with a specific program is required for each operation. If, moreover, flexibility is required (there are different types of reducing gears) it can become difficult to manage the Page 2

5 RLS-3 - RLS-3 - RLS-3 - RLS-3 - production line. When a RFID system is used, it becomes very easy to insure flexibility. Instead having a person who programs the machine, with the possibility of being wrong, the type of program required can be written into the transponder. Milling machine Drilling machine Gear cutting machine RWM RWM2 RWM3 RWM4 Conveying belt Read/Write Module RWM writes into the transponder the instructions to program the different working stations. The figure below shows the memory of the transponder after having been written. Memory of the tag Instructions concerning the surface treatment machines Instructions concerning the gear cutting machine Instructions concerning the drilling machine Address Instructions concerning the milling machine Customer, production order number, etc. This is a very clever application of the RFID because it allows to automatize the production line and it gives it a great flexibility: the machines are programed by the content of the transponder s memory. Surface treatment area and drying area As in the case of the machining area, it is possible to give instructions to the machines that make the treatments (cleaning, electroplating, painting, anodic oxydation, etc) via the transponder. Considerations about the choice of the RFID system In order to have indications on the types of RWMs and tags that can be used for each location, their environment has to be defined: Metallic environment Temperature range Chemical constraints Mechanical constraints Electromagnetic interferences Embeddability Others. Page 3

6 Subsidiary question are: What is the number of pieces which need identification tags? What is the number of tags that will be permanently attached to the device (which means that they will be lost and can be considered as consumer goods) What is the number of tags that will be reused (tray carrier)? The answers to all this considerations allow to define the types of RFID components which can be used. Control area The pieces which are coming in the control area are ready to be mounted. Various operations are made at this location. The carriers must be returned at the beginning of the line where they will be cleaned before being reused. In order not to loose the data stored in the transponder, they will be transmitted to the central data base. Those data contain the whole history of manufacturing the pieces. The pieces are controlled and placed in a new container on which is also affixed a transponder. Data stored in the transponder at that location are the following: data concerning the customer production order number designation of the pieces placed in the container assembling instructions test program to use data relevant for traceability Assembly area The device is assembled following the instructions stored in the transponder, that means that the transponder will be read when the container comes into the assembling area. At the end of the process, the new part number of the device is written into the tag as well as, for example, the number of the employee responsible of the assembling. The date and time at which the device can leave the assembling area can be stored also into the tag. Test area The test parameters are read from the transponder and transferred to the test machine. After having performed the tests, one writes the results into the transponder as well as the serie number of the device. There also, it is possible to add other information like, for example, the employee number of the person who has supervised the tests. Packing area In the packing area, a transponder will be embedded and screwed in the back of the finished device. Data like the serie number of the device, the final test results, the production order number and all the data which are specific to the device will be copied from the tag on the container and transferred to the tag embedded in the device. This tag becomes the identity card of the device which will be useful to insure its maintenance. Page 4

7 Back side of the reducing gear Tag embedded in the device RT P After this operation, the device is packed and sent to the shipping area. Operations in the shipping area All the data contained in the transponder affixed to the container are read and transmitted to the central data base to be archived. The container can be sent back to the control. The papers relative to shipping (delivery note, customs documents, address of the customer, etc) can be printed and attached to the shipment. Contribution of RFID during production Layout of the RFID system in the production plant The figure below shows the implementation of the RFID system in the production line. Industrial fieldbus X x 456 x DIAG RS-422 HF Interface RS-232 X3 RWM4 RWM5 HF RLS-3- RLS-3-2 RLS-3- RWM3 RS-485 RWM2 X2 Interface #2 ADR COM Interface # MMC APL SYS 2345 Packing 2345 RLS-8 Shipping RLSS 2 RWM RLS-3- RWM5 RLS-8 Machining Stock RWM4 HF Drying Surface treatment RLS-8 RWM3 HF 2 RLSS RWM RLS-33-2 RWM HF Test 6789 Assembly 6789 Control 2345 RLS Reception RWM2 HF Page ContriNet

8 : / GHI PQRS 5 8 ABC JKL TUV.,?! 6 9 DEF MNO WXYZ # There are two different RFID networks: one, in blue, is a low frequency () network and the other, in red, is a high frequency (HF) network. Low Frequency network Low frequency RFID is used because it allows to work (Read and Write) through metal and in metallic environment. This means that it is possible to have metallic Read/Write Modules (RWM) as well as metallic transponders. These components are sealed and are able to work in harsh environments like a machining area (with oil and metal chips) or a surface treatment area (with various chemical products). The disadvantage of low frequency RFID is that the operations are relatively slow. So it is, for example, not possible to read from or to write into a large zone of memory on a tag which is moving. In order to connect the low frequency network to an industrial fieldbus (RS485, PROFIBUS-DP, DeviceNet, Ethernet/IP, etc), interfaces are used. It is so possible to control the whole low frequency RFID network through a central industrial computer (PLC for example). Contrinex offers interfaces with the possibility of connecting up to four Read/Write Modules. High Frequency network High frequency RFID is very fast (about ten times higher than the low frequency). If one have a lot of data to store into the transponder, like test results for example, it is appropriate to use high frequency RFID. It is also possible to connect the HF RFID network to an industrial fieldbus through an HF interface. Contrinex offers an innovative solution with its ContriNet. ContriNet is a network which allows to connect in serie up to 32 Read/Write Modules. The advantage is then evident because the number of HF interfaces can be drastically reduced. The disadvantage of the high frequency RFID is that it is not able, without some specific tricks, to work in a metallic environment. That means that it is not possible to make metallic tags and metallic Read/Write Modules. The components are so not appropriate to work in an harsh environment. Contribution of RFID for warranty management/maintenance It was shown that the RFID allowed to insure the traceability of a device during its manufacturing. It was also shown that the tags can contain information able to command a machine. This point is very important because RFID is a vector of automation and flexibility of a production line due to the information attached to the device to be machined. The whole history of a device, at the end of the production line, is stored in the central data base. In case of claim, it is always possible to know what happened at each step of the production process. The tag affixed to the device will be usefull for maintenance. The type of maintenance as well as the date of intervention will be stored in this tag. Updating the content of the transponder during the maintenance on the customer site is done through a handheld read/write module. RTP Updating the data in a transponder with a handheld Read/Write Module Page 6

9 It is to be noticed that it is also possible, in that way, to follow the maintenance of the machines of the production line. Economic considerations Preamble Generally, the RFID system will replace an obsolete identification system. In order to have a relevant comparison between the current system and a future RFID system, it is necessary to analyze the costs linked to the current system and the investments and costs linked to the acquisition of an RFID system. The target of the points that follow is to quantify, even approximately, the various costs involved in identification, to analyze the investments to do and to draw, from these two approaches, relevant arguments to demonstrate finally the merits of the acquisition of an RFID system. Costs linked to the system without RFID (Current system) Initial investments There was probably an initial investment for the current system which represents a fixed cost. As the current system was certainly more manual than the RFID system, it can be assumed that the initial investment was relatively low in comparison with the investment to do to aquire an RFID system. Consumption and replacement of identification material It can be labels or barcodes; certain papers, like clean room papers, are quiet expensive. It can also be some kinds of containers. This category represents a part of the variable costs. Personnel costs It is certainly the most important source of variable costs. There are two reasons to spend time in the area of identification. The first one is to trace the objects and the second one is to correct the human errors like transcription errors or omissions. Representation The various components of the costs are reported in the figure below. Costs without RFID Total costs without RFID Initial investments for identification system Consumption and replacement of identification material Personnel costs Page 7

10 Costs linked to the system with RFID RFID components The costs for interfaces, Read/Write Modules and transponders in closed loop represent the initial investment or fixed costs for the RFID system. The costs for the transponders considered as consumer goods represent the variable costs for the RFID system. Representation The costs listed in the above paragraph are reported in the figure below. Costs with RFID Total costs with RFID time Interfaces Read/Write Modules Transponders in closed loop Transponders considered as consumer goods Synthesis Breakeven Superposing the curves of total costs without RFID and total costs with RFID, it will be possible to calculate the time T when breakeven is achieved. The breakeven is the instant when RFID system becomes more profitable than current system. Total costs Total costs without RFID Total costs with RFID time T RFID profitable Page 8