Current technology involves stationary sensor tunnels measuring the same models repeatedly at high throughput. However, flexibility is limited because each measuring point requires a sensor on a fixed support. Furthermore, measuring-point modi-fications or model changes result in additional sensors or long adjustment periods ranging from several hours to several days.

The BMW plant in Spartanburg, SC, in its search for a more flexible gauging system, chose a Flexible Robotic Absolute Measuring System (FRAMS) from St¿li (Duncan, SC), which can be used in-line and off-line. FRAMS can reduce costs compared with fixed sensor solutions in instances where flexibility is a priority over throughput. Easy model changes or short measuring point modifications can be accommodated within minutes. The system also has high accuracy and repeatability and needs only one sensor.

The manufacturing facility now uses Z3 frame gauging on 300 car bodies per day. This flexible in-line system integrates four RX130 L robots. Each are equipped with 3D Perceptron laser triangulation sensors. The system measures 10 different model types. To verify tolerances, four RX robots measure 137 points in 92 seconds on Z3 bodies with ±0.15-millimeter repeatability without temperature compensation. The focal point of this automation is improved quality. In a second off-line application, a RX130 L robot on a linear track inspects car body parts using an optical coordinate measuring machine. Assemblers communicate with the system through a graphical off-line user interface.

The RX robot's high repeatability yields increased quality measurements. Its high speed allows faster sensor repositioning, resulting in more measurements. The FRAMS temperature compensation and the calibration for absolute measurements and measurement point definition directly on the computer-aided design guarantee the necessary measuring system repeatability and accuracy.

For more information on the Flexible Robotic Absolute Measuring System, call St¿li at 864-433-1980, visit www.staubli.com or Reply 5.