Application of RFID technology in the manufacturing process

The use of RFID technology in the manufacturing process can bring many benefits and potential cost savings. RFID technology has been more rapidly accepted in the manufacturing process because the RFID technology can be a reusable product when the RFID tags are embedded into fixtures used in the manufacturing process. Many manufactures use some type of fixture, tray or tote to carry the parts needed to build their product.

Typical production starts with an order being sent from the company server to the factory floor and then printed out in paper form for the operator to know what parts go into the tote with each order. When using RFID tags embedded in the fixture, such as a tray or tote, the need to print a paper order can be eliminated. The order information can be sent directly to the tag and the fixture can be automatically routed to the first part pick location in an automated conveyor or delivery system. This then makes the process paperless or “green,” saving manufacturing costs and reducing impact on the environment.

Once the order information is written to the RFID tag, the data can be used to move the product throughout the manufacturing process. The location and status of the order can be tracked at any point in the process by reading the RFID tag with an antenna reader located at that point. After the product has been completely assembled and shipped to the customer, the fixture is taken back to the beginning of the manufacturing process where the old data is deleted and new data can now be written to the tag. The RFID tag can be re-written with new information thousands of times as long as the tag is not physically damaged during the manufacturing process.

Now let’s take a closer look at what specific hardware might be used in the process described above. RFID readers are used in a factory that uses totes for collecting parts and materials to build its product. There is room for about 500 totes to be used in the production process, moving the totes to assembly areas via automated conveyor. Each of the totes is fitted with a passive RFID tag that is glued to the inside bottom of the tote and then covered with a foam mat to keep parts and materials from damaging the tag.

Passive RFID tags don’t require batteries or other external power sources to hold information. They are energized by the RFID antenna when they are within its range. Active RFID tags contain a battery or some other active power source that must be maintained in order for the tags to be used. There are many applications were this is necessary such as tags used to track products being shipped in trucks.

In the typical manufacturing environment, a passive tag will work just fine because the application allows the presentation of the tag to the antenna to be controlled in terms of distance from the antenna, and the types of materials around the tag. Passive tags are also much more economical to purchase than active tags.

Totes are injected at the beginning of a conveyor line where a reader/writer is installed. Information is written to the tag from the central computer via connection to a PLC. The reader/writer can be connected to the PLC via serial RS-232 or Ethernet. Newer antennas are now available with both Ethernet and RS-232 capabilities.

Once the order information is written to the RFID tag in the tote, the tote is sent down the conveyor line along a Pick To Light – a series of part pick locations. At each location another reader/writer antenna is installed to read the tag and parts needed from that pick location were displayed on a monitor above the conveyor line with a corresponding indicator light illuminated on the flow rack physically holding the parts for the operator.

After all parts are picked into the tote, the tote is sent to an assembly area. At the beginning of the assembly area, the tote is read by another antenna to determine which assembly station is equipped with the correct tools and skill set to build the end product. Based on the available destinations, the totes are delivered to the correct assembly location and the location given to the company server for inventory update.

After assembly is complete, the finished product is placed back in the tote and sent to an automated final packaging area. The totes are read by another antenna at the entrance to the final packaging area and the correct packaging material is sent to the packaging machine. Once the finished product is packaged and sent on the way to the customer, the empty tote is returned to the beginning of the process to be re-written for the next order.

The use of RFID technology in the manufacturing process offers many benefits to a manufacturing process. RFID can reduce the amount of paper needed to create the product, it allows for better tracking of inventory, more accurate status of WIP, fewer manufacturing errors and a higher quality product. Capturing the benefits of RFID technology in this arena is relatively easy compared to some other applications because the RFID tags can be of the passive type and can be reused. It makes the value proposition very attractive for that reason alone.