Beyond track-and-trace: Using RFID on the factory floor

RFID has moved beyond logistics to become a link between the plant floor and the enterprise.

02/13/2013


Industrial manufacturing continues to evolve, constantly adapting to meet the ever-increasing productivity and efficiency demands on the factory floor. RFID technology has been providing manufacturers with high-quality, reliable product track-and-trace functionality throughout the supply chain, but this intelligent monitoring system technology is also a valuable asset within the production environment. By using RFID as a manufacturing tool, companies are redefining production standards with improved execution, efficiency, and product quality. 

Figure 1: Industries can use RFID systems for automated processes to control and monitor operations and refine schedules, directly impacting their efficiency gains and improving production. Courtesy: Turck USABefore RFID systems that could withstand extreme environmental conditions were developed, manufacturers were not able to achieve the unique visibility and control this technology offers. Now that RFID can perform in high temperatures, high pressures, hazardous locations, and wet environments, manufacturers can use these systems for automated processes to control and monitor operations and refine schedules, directly impacting their efficiency gains and improving production (see Figure 1). 

RFID offers major advantages compared to optical identification methods such as barcodes. The use of this technology spans a diverse range of industries including oil and gas, chemical, pharmaceutical, automotive, and other industrial manufacturing processes. By incorporating RFID tags and readers into the manufacturing environment, users can increase production visibility and control with continual real-time status updates. Providing immediate access to tool locations, equipment tracking, and process data, RFID delivers an essential element for achieving previously unmatched production streamlining. 

How it works

When selecting and implementing the appropriate RFID solution for each application, manufacturers should know the speed and proximity required for products to successfully pass the read/write heads. Variables such as data size and distance also impact the viability of the solution. Therefore, supplying only general information such as recommended read/write intervals or transfer rate is typically insufficient when identifying the appropriate system for the application. 

Unlike conventional auto identification methods, such as barcodes or the data matrix code, RFID transmits information using electromagnetic radio waves, which eliminates line-of-sight requirements. While printed labels attached externally to a product or component become unusable by the time they are exposed to high temperatures or moisture, special RFID tags and mobile reading devices make it possible to use RFID systems even under harsh industrial conditions. 

An RFID system contains three parts: tag, transceiver, and interface. Tags can be active (requiring a battery) or passive, reflecting the signal back to the transceiver, which is often called a reader or antenna. The interface transfers the data from the tag to a data collection device such as a computer or a PLC. 

The transceiver reads the RFID tag. An I/O device communicates with the enterprise or higher-level control system to provide tag information. RFID tags contain internal circuits that respond to an RF field emitted by the transceiver. During operation, when an RFID tag passes through the transceiver’s field, the tag detects the signal from the antenna. This signal activates the RFID tag, enabling it to transmit or receive information on its microchip.

Originally, this technology was developed as a method to remotely gather data through tags or transceivers. However, because of their data storage capacity, manufacturers have been attaching or embedding these tags into objects during production and programming them with information about the product, equipment, or tool. By gathering more data through tags, RFID allows users to read and write meaningful data—process information—to the tag. 

Some RFID systems feature state-of-the-art nonvolatile ferroelectric random access memory (FRAM) storage technology, which allows 106 write operations and an unlimited number of read operations on a single data carrier. With this type of read/write capacity and the ability to be used in applications that require repeated write operations, manufacturers can reduce or eliminate replacement data carriers. Plus, RFID systems now exist that allow read and write operations to be easily programmed to the data carriers at any location with a handheld unit and enable data to be displayed on an illuminated touchscreen in decimal, binary, hexadecimal, and ASCII code formats. From this point, manufacturers can easily and conveniently manipulate data, editing and writing it to the appropriate data carrier as required. 

To accommodate versatile and challenging application requirements, data carriers are available in a variety of shapes and feature diverse read/write intervals, with high-frequency technology allowing read/write operations at distances from 5 to 500 mm, and UHF technology allowing read/write operations at up to several meters. 

Systems have also been designed to withstand a wide temperature range, including data carriers that can operate in extremely high temperatures and those that require no cool-down time for read or write operations. These enhanced thermal characteristics can significantly increase productivity rates on the plant floor. Additionally, to satisfy fast-paced manufacturing environments, innovative RFID systems have been engineered to read or write data simultaneously at 0.5 msec per byte, and some are even capable of on-the-fly production speeds of 10 msec at distances up to 500 mm. 

Along with meeting speed and distance requirements, RFID must also be adaptable enough to adapt to industry changes. For inherent scalability, modular RFID systems with built-in I/O capabilities enable this technology to keep pace with growing manufacturing demands. Users can add discrete, analog, and/or eight-channel RFID modules to the system to expand single network nodes. RFID can be integrated into existing platforms and supports common protocols including Profibus-DP, DeviceNet, Modbus TCP, Profinet, and EtherNet/IP, which allows flexible connectivity, communication, and production visibility. 

RFID on the plant floor

Figure 2: Through RFID tags, manufacturers can access data on the contents, location, and usability of equipment and materials, enabling them to decipher current production status, identify potential problem areas, and optimize planning strategies. CourteWhile tracking products through the supply chain can promote product quality and customer satisfaction, RFID can also be used internally to improve process efficiency and decrease costs. For example, manufacturers can use RFID technology to monitor equipment within the facility by tagging machines, conveyors, trucks, or forklifts. Through these tags, users can access data on the contents, location, usability, and maintenance requirements of each piece of equipment. This knowledge enables users to decipher production status information, identify potential problem areas, and help develop planning strategies for production performance optimization and effective labor/asset allocation (see Figure 2).

Inventory management

Accurate inventory information is important to the efficiency of every plant. RFID technology can help improve inventory management. By tracking products and equipment, RFID helps regulate the inventory of a manufacturing unit, allowing users to better forecast their needs with real-time data on raw material, equipment, or supply demands. Also, by maintaining equipment and tool location inventories, RFID can improve production scheduling or eliminate the need to reorder materials that are thought to be lost. 

When RFID is implemented for inventory management, users can effectively reduce costs and waste by applying the technology to increase product visibility and enhance stocking/reordering processes. RFID can locate tagged materials and supplies. Using RFID technology to manage equipment and tool locations allows users to improve production scheduling by identifying which objects are in use or can be allocated to a specific project. Further, the ability to pinpoint the amount of remaining supplies and their exact locations can improve production line movement, decreasing downtime and shrinkage. 

Because plant floors are often busy, chaotic environments, shrinkage is common. Inventory shrinkage refers to a number of unrelated causes that render products unaccounted for under inventories. This could include materials that are no longer usable or items that are lost or damaged. Shrinkage can also occur when employees purposely keep assets/tools accessible in convenient places. This makes it appear as though these items are missing from inventory, leading to unnecessary replacement purchases. With RFID tracking in place, locating these assets is easier, which saves search time and replacement costs. 

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