COMPTON, CA—A new instrument for volumetric calibration and compensation of CNC machine tools has been introduced by Optodyne, Inc. of Compton, California.  Volumetric calibration of CNC machines with Optodyne’s Laser Doppler Displacement Meter (LDDM) based system, provides a check of the machine tools volumetric accuracy, by compensating for the errors measured by the system, including linear, squareness, and straightness, the overall machine tools performance is improved. 

In less than four hours, an operator can calibrate a CNC machine tool with a working volume of less than one-cubic meter with four easy setups.  The system automatically generates up to 18 compensation files, which include six bi-directional linear errors and 12 bi-directional straightness errors.  Compensation file formats are available for Giddings & Lewis, Milltronics, Siemens 840, Fanuc 15 and Fanuc 16 controls, with many others in development.  The system can be used to calibrate CMMs (coordinate measuring machines), precision measuring machines and XY stages.

            By measuring volumetric errors, Optodyne’s software can generate a compensation table, which can be downloaded to the control.  The table compensates for the machine tool’s whole volume, which improves overall accuracy of the machine tool.  For example, most machine tool calibration systems check for linear displacement errors (linear error parallel to the axis of movement).  Therefore, vertical straightness error (perpendicular to the axis of movement), as well as the horizontal straightness error (perpendicular to the axis of movement and the vertical straightness direction) is not measured.  The result is a vector error, which consists of displacement error, vertical straightness error and horizontal straightness error.

Compensation tables are automatically generated by Optodyne’s Windows-based software, which measures volumetric performance, as recommended by the B5.54 standard (ASME).  The software runs from most notebook or desktop PCs and does not require add-on cards.  Data is displayed on the computer screen or printed in tabular and graphic format.

Optodyne’s LDDM technology utilizes a modulated laser to reflect a beam off of a movable target.  The beam is detected and processed for displacement information used by the control to determine position.  The laser head features a stability check of better than 0.1 PPM, accuracy of 1.0 PPM and resolution up to 1 microinch.  The system comes standard with sensors to automatically compensate for environmental factors, such as barometric pressure, air temperature and material temperature to compensate for thermal expansion.  The system is calibrated and traceable to NIST and software analysis supports NMTBA, VDI, ISO and ASME B5.54 standards.

Optodyne, a California corporation, develops, manufactures and markets laser-based precision measurement equipment for machine tool calibration, metrology, OEM, and other industrial applications that require precision measurement.  The company's products are based on the patented Laser Doppler Displacement Meter (LDDM) technology developed by Dr. Charles Wang, Optodyne's president.