In sports, when the competition turns up the heat, a good coach turns to a clutch player who can withstand the pressure.

At Visteon Corporation's Nashville glass plant, making a windshield is a high-pressure, high-temperature business. Inside the autoclaver, where vinyl is bonded to windshields for the Ford Motor Co., the temperature can reach 300 degrees Fahrenheit. During the forming process, the glass is shaped under 250 pounds of pressure. To track those windshields, Visteon chose a radio frequency identification (RFID) solution (Escort Memory Systems, 831-438-7000, www.ems-rfid.com ) for its ability to withstand those conditions and ease of accurately tracking windshields.

"On this line, it's imperative that we have the right part at the right place at the right time because the finishing operations are designed for specific windshields," explains Lin Taylor, an engineer with the advanced engineering group that developed the RFID project. "If we misidentify a part, an operator has to manually manipulate the system to remove the part. That has immediate ramifications to throughput and can back the system up."

Despite the hazardous environment, Taylor says, the RFID system has been up to the task. Like a clutch player, the system has consistently provided accurate and reliable information that keeps the line humming.

Visteon is the world's second largest automotive supplier. With $19.4 billion in annual sales and 84 production facilities, the company produces components and systems such as climate control, chassis, and commercial glass for 18 of the 20 largest vehicle manufacturers. Visteon parts typically represent over 40% of the total materials value of the average vehicle.

When the parts supplier designed a new production line for the Nashville glass plant, Visteon knew it needed a more reliable and accurate tracking process for the windshield finishing line. The previous method of tracking windshields – a magnetic coding system – had reliability problems. More importantly, the process had become obsolete.

A number of alternatives were investigated, says Taylor. A bar code system, for instance, could have been designed to withstand the heat and pressure. However, labels would have required frequent replacement because the racks that carry the windshields are filled several times during a shift and may carry a different windshield type on every trip.

"We also considered using a queue in the programming of our programmable logic controller," Taylor adds. "That, however, would have required some very complex programming that would have unnecessarily increased the size of the PLC."

Visteon even considered using an employee to manually identify the windshields, but that was too costly.

Visteon's system relies on passive read/write tags capable of withstanding high temperatures and high pressure, reader/writers, and an interface module to communicate to the PLC. Information can be erased and rewritten to the tags for every trip.

"In the end," says Taylor, "RFID was the most flexible, reliable, and cost-effective solution. The tag is permanent. Regardless of where the racks go, we can identify the correct part on that rack."

The Nashville plant produces windshields for a wide variety of car and truck models.

At any given time, two different windshields are being produced on two separate manufacturing lines. The lines produce nearly 320 windshields per hour.

The lines merge at the autoclaver. Inside that vessel, the windshields are heated under pressure to nearly 300 degrees for maximum adhesion of the vinyl layer to the glass.

Prior to going into the autoclaver, the windshields are loaded by robot onto a rack that holds 53 windshields.

An RFID read/write tag is mounted directly onto each rack. Passive reader/writers are attached to the conveyors that transport the glass racks. Once the windshields are loaded, the glass type information for that rack is written on the tag by reader/writers prior to autoclaving.

The racks are then conveyed by a trolley system to a loading conveyor at the autoclaver. Eight racks fill the vessel for each 90 minute cycle. After vessel loading, the conveyors feeding the autoclaver are retracted, and the cycle begins.

Once autoclaving is finished and the racks removed from the vessel, the windshields are ready for transportation to work cells.

"The autoclaver can hold various combinations of parts from both of our production lines," explains Taylor. "But the finishing lines are set up for a particular part shape. That's why we need to be able to distinguish the windshields on one rack from another."

At a decision point in the system, the RFID tag is read to determine if the part required at a work cell is the same as that on the rack. If there is not a match, the rack is sent to a queue station to await its turn. That continues until a rack with the correct part appears at the decision point.

Once that happens, the rack is loaded onto an automated carrier that transports it to a work cell on the finishing line. There, a robot unloads the rack. The robot then requests a new rack. When the next carrier arrives, the newly arrived full rack is swapped for the just emptied rack, which is then transported back to the loading station at the beginning of the loop. There, the tag is erased as it enters a pool of empty racks awaiting a load for the autoclaver. The empty racks continue on a loop where they wait in a queue to be loaded for the next trip to the autoclaver.

After rack reloading, information about the new windshields is written to the tags and the autoclaving cycle begins anew.

"The system is simple to use," says Taylor. " We write the glass type info to the tags, and no matter what happens during the process, the info is still there. The tags have easily handled the temperatures of the autoclaving process."

In fact, Taylor adds, the RFID system has more capabilities than Visteon is currently using. "Right now, we're only differentiating between the two lines of information, but we could easily expand the system if we needed to add more production lines."