5.22 - Automatic Identification
Automatic Identification of items in manufacturing is integral with efficient, cost effective and high quality production or material storage. It can be introduced into virtually any environment if a holistic approach to system specification is used and the appropriate choice of identification technology is made. The need for automatic identification comes from the need to have rapid and current information about the items within a system. An item can be any of the following things:-
- Raw Material
- Part or Component
- Kit of parts
- Sub-assembly
- Assembly module
- End product
- Tools
- Consumable Items
- Carrier or Container
- Packaging
General Background
Particular identification systems are associated with each identification technology whereas there is often a choice of marking techniques dependent on the specific conditions of the application. It is vital to the success of the identification system that the marking and reading techniques are compatible. Decisions about each of the following aspects must be made before any one technology can be specified for a given application:-
- Form or required information (numeric or alpha-numeric)
- Range of information
- Frequency of use of information
- Desirable method of control of information
- Location of information (on components or containers)
- Acceptable quality levels of information
Stages in the identification process
- Item recognition
- Allocation of required information
- Marking or labelling
- Reading the information reliably
Stage 3 is critical. The efficient operation of the whole manufacturing system depends on the correct choice of marking or labelling in association with reading techniques. Coding systems that allow small accumulative errors can be inadequate when large volumes of throughput of high variety products are being monitored. In this case the devices must be foolproof.
Automatic Identification Technologies
Automatic identification technologies include the following:-
- Barcodes
- Optical character recognition (OCR)
- Magnetic Ink Character Recognition (MICR)
- Smart cards
- Radio Frequency Identification (RFID) Tags
- Magnetic Strip (or Stripes)
- Vision Systems
- Mechanical Proximity Sensors
- Optical Proximity Sensors
- Mechanical pins and holes in binary code with simple mechanical interference checks (similar to the Jacquard system)
Each technology has its own ideal applications.
A General Summary of Marking Systems and Their Applications
| Item to be marked | Labels |
Type of identification |
Parts |
Pallets |
Plastics |
Metals |
Flat |
Round |
Contours |
Papers |
Poly |
Foil |
Metal |
Thermo impression |
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Hot foil marking |
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Stamping |
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Pressing |
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Engraving |
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Etching - Electro-chemical |
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Etching - Vibro Etch |
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Stylus Marking |
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Roll Marking |
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Laser Marking - YAG |
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Laser marking - CO2 |
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Tampo Printing |
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Ink Pad |
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Marking pens / chalk |
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Paint |
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Transfers |
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Ink Jet |
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Silk Screening |
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Thermo Printing |
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Dot Matrix Printing |
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Labels |
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Micro chips |
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Magnetic strips |
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Permanent magnets |
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Example - A Pallet Identification System
A code and reader system using permanent magnets is ideal for JIT cellular manufacture where a dedicated number can be allocated via a local database to specific contents.
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Card Code
- Simple format - standard sizes for Kanban card holders
- Low cost
- Durable - withstands high temperature and hostile environments. Has fixed cost value, can withstand multiple reads
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Conveyor Application |
Code Reader
- Extremely reliable - over 100,000 test reads without error
- Low cost: equivalent to a bar code wand reader
- Compact and comfortable for manual use
- Provides human readable display for operator involvement
- Non-contact sensing with physical location fore ease of operation
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Portable (Hand Held) Reader |
The identification system is based on the use of dedicated pallet codes associated with specific contents using a computer database. From the time the contents are loaded into the container until the unload authorisation is recorded, the same contents are assumed by the system every time the pallet code is read. After unloading has been logged the same pallet can be allocated for other items. |
Permanent magnets are used to produce a binary code in a durable form which read by magnetic field sensors. Various other methods could be used, from optical mechanical pins in binary code.
Some readers interface directly with computers and give a direct digital readout and do not require a decoder as complex as those for bar codes.