Laser Trackers Bring Speed, CMM Accuracy to Part Measurement
The large machined casting and fabrication manufacturing sector, which encompasses ship building, heavy machinery, wind energy and numerous others, must precisely measure 3D part features and their geometrical relationship to other critical features, integral in large physical parts. Over the past decade, the Laser Tracker has increasingly become the ‘go-to’ product for measuring and validating large scale manufactured parts. The Laser Tracker measures 3D coordinates by tracking the laser beam returned from an SMR target held in contact with the part feature under measurement.
In the past the domain of the inspection of large fabricated and precision machined parts belonged to the ‘monster’ gantry style Coordinate Measuring Machines (CMM). Apart from being very expensive, these CMMs required specialized machine foundations and had to be housed in large temperature controller enclosures. The machines also required problematic part transportation to the CMM room and climatization before measurement. Also, unless these large parts were manufactured in quantities, CMM measurement was slow as part inspection had to be performed under CMM joystick control since the writing of the necessary complex inspection part-programs to measure parts automatically was deemed too time consuming and uneconomic.
Today, Laser Trackers cost a fraction of the cost of a monster CMM and are portable so measurements can be performed on the manufacturing floor, regardless of the environmental hostility, typical of large fabrication and machining shops, and can provide measured results almost instantaneously. In addition, measurements can be performed with ease after each manufacturing operation rather than waiting to measure only the finished part as is often the case with large CMM inspections. Laser Trackers can measure part features up to 80 meters away or as close as 2 meters. The API RADIAN PRO Laser Tracker offers single point accuracy, in the 2-5 meter tracker measuring range, of just 2.5 microns, making it more than a match for the most accurate of CMM measurements.
To compliment the Laser Tracker measurement capabilities API has developed its vProbe which is a hand-held measurement accessory with integral SMR. The wireless vProbe allows internal part features to be measured using CMM style ruby styli that allows emulates 3D CMM part inspection techniques.
Laser Trackers have become the most versatile of 3D coordinate measuring devices available to large volume manufacturing companies, and most popular metrology software’s now recognize the growing role of the Laser Tracker and offer a seamless interface and integration. Many have also developed tracker specific functionality, further improving tracker measurement productivity. Another role of the Laser Tracker in large volume machine shops is in the calibration of the large machine-tool used to machine the large fabrications and castings. Using a self-orientating motorized 360O rotation SMR, that locks onto the Laser Tracker, machines errors can be measured allowing machine geometry to be compensated or adjusted accordingly.