Fanuc CNC America, a manufacturer of computer numerical controlled (CNC) controllers for machine tools, has teamed with sensor maker Balluff Sensors Worldwide to offer miLink Tool ID, a device enabling an interface between Balluff’s RFID-based sensor system and Fanuc’s controllers for tracking tool use in manufacturing systems. Fanuc has a 51 percent share of its market, selling machine-tool controls to such machine-tool builders as MAG Cincinnati, Hardinge, Romi and Mori Seiki. The company currently has 300,000 units in use in the United States.
CNC controllers operate machine tools used to manufacture products. The devices run a variety of tools, including drills, cutters and grinding wheels. The type of machine tool is dictated by the specific application the manufacturer is undertaking. Historically, machine tool operators have needed to manually input data regarding each tool as it is placed in a machine’s “tool changer,” which is similar to a carousel. In addition, because a tool can be used only for a specific amount of time or a particular number of tasks, the operator has needed to keep track of how the tool has been used, or examine it to determine if it is getting worn out. There is always the possibility of human error, causing a system to shut down because a tool either broke during the manufacturing process, was not operating properly due to being worn out, or was not installed in the correct location and was thus being used inappropriately.
Balluff and Fanuc believe RFID can be employed to reduce the chance of human error. MiLink Tool ID—a small, box-shaped device containing an interface module, RFID middleware and a processor unit—receives RFID data from a reader in the controller, via a cabled connection. The interrogator reads tags on tool holders inserted into the machine tool, and directs that information to the appropriate location in the CNC controller (which utilizes data regarding which tools are located where, in order to adjust the machine’s operations, or to send an alert if the wrong tools have been installed). The miLink box became commercially available in January of this year.
The tool holders’ RFID tags are encoded by a reader installed at a presetter (a device that determines the type of tool in use, as well as its specifications). Presetters, which are designed to help manufacturers track the type and size of tool being utilized, measure the tool automatically, using cameras to take an image of it. A presetter uses that image to calculate the tool’s size and type, and then stores that data, which a worker prints on a paper label and later inputs into the CDC controller to guide the machine tool’s operation.
Balluff’s RFID sensor system consists of an interrogator and an RFID RS232 processor that provides software to exchange information between the presetter and the reader. Prior to the release of the miLink Tool ID, end users (such as automotive, aeronautics or health-care device manufacturers) had no simple means for automating their presetter data. If they installed Balluff’s RFID sensors to link information from the reader to the machine tool controller—to date, approximately 1,000 customers worldwide have done so—they would have had to hire an experienced integrator, who would typically spend several days or weeks of integration work to allow the controller to understand and respond to data from the RFID reads, explains Mark Sippel, Balluff’s product marketing manager.
For that reason, Sippel says, many end users have opted against using RFID. Balluff and Fanuc teamed up to solve the problem, and Fanuc developed the resulting miLink solution. Both companies now sell the miLink Tool ID device with their own products.With or without miLink, Balluff’s RFID system automates the movement of data from the tool presetter to the CNC controller. The company’s system works with small, dual-frequency passive RFID tags (usually 10 millimeters in diameter) embedded in the holders in which tools are stored. Once the presetter automatically measures a tool (reducing man hours previously spent when employees had to manually measure tools), the data related to those measurements is transmitted to a Balluff RFID reader-encoder plugged into the presetter.
The encoder uses a 70 kHz signal to write the details onto the Balluff RFID tag embedded in the tool’s holder. “The lower the frequency,” Sippel explains, “the more power you can reliably induce when the tag is embedded in metal.” Data includes the type of tool, its measured dimensions, the date and whether that tool is new or used. Typically, he adds, 511 bytes are required to store such information, though the tag can hold as much as 2,000 bytes.
An operator takes the tool, in its holder, and places it in one of many pockets located on the machine tool carousel. A Balluff RFID reader in the machine tool reads the tag at 455 MHz, using a proprietary air-interface protocol. The higher frequency is used in the reading of tags, Sippel says, because less power is required for reading than for writing. “We have developed a version with similar tag/antenna technology for new installs that complies to ISO 15693, though, if desired,” he states.
The new miLink Tool device receives data from the reader via an RS232 cabled connection, translates that information, determines where that data needs to be stored in the controller, and sends those instructions to the controller via an Ethernet cable. The controller then takes that information and adjusts its own settings to operate according to the specifications of the particular tool inserted. The controller can also trigger an alert based on RFID data that would indicate a tool has been attached to the wrong location on the machine—such as a drill being affixed where a cutter should be.
Information from the miLink box also allows the controller to track the number of times a tool has been used, and the controller can then issue an alert, such as lighting up an indicator on the controller panel, or shutting down the machine, if a tool has reached its lifetime, or needs to be sharpened, and no one has removed it. “This system can eliminate human error,” Sippel says, which can have a high cost for manufacturers since sophisticated machinery can be expensive to repair. In addition, a misused tool or a system shutdown can cost a manufacturer many hours in productivity.
What’s more, says Gary Highley, Fanuc CNC America’s engineering manufacturer, the miLink box can send instructions to the CNC machine to write data onto a tag, such as updating the hours it has been in use, so that if a tool is moved to another machine, its usage data goes with it.
“The miLink box is intended to save people the engineering time in integration,” Highley says. If a manufacturer wanted to retrofit its existing system with RFID capabilities, he notes, it could simply purchase the RFID hardware from Balluff, and the miLink device from Fanuc. “If you have to pay an integrator, that adds up in a hurry,” he states. “We wanted to relieve end users of having to do that.”