Combining a highly accurate CERTO length gauge with an ND 287 digital readout (DRO) equipped with Statistical Process Control (SPC) enables Heidenhain Corporation (Schaumburg, IL) to offer a powerful new inspection system. Since the new universal Heidenhain ND 287 also has a card for gauge hookup as well as other sensors, it was certain to tie-in with CERTO, an established gauge capable of a large measuring range, including high accuracy nanometer-level measurement. Common applications for this system are inspection of parts with tight tolerances and gauge block calibration.
The length gauges of the Heidenhain-CERTO program measure ranges of 0-25 mm at ± 0.1 µm accuracy / ± 0.03 µm after error compensation, and 0-60 mm at ± 0.01 µm accuracy/ ± 0.05 µm after error compensation. Error compensation is handled and stored by the ND287 in conjunction with manual input of values from the accuracy chart included with each CERTO length gauge. The CERTO is comprised of an ultra low thermal growth material, ZERODUR, for the glass scale and an invar shaft in order to significantly decrease thermal effects. Since a graduation and reference mark are imprinted onto the glass scale, drifting, as seen in LVDT technology, is nearly nonexistent and difficult to measure.
When combining Heidenhain-CERTO with the new ND 287 single-axis position display with its many features designed to more fully integrate in a machine data transfer network, the new Heidenhain system becomes an especially powerful tool. The ND 287 itself allows up to four inputs with varying interfaces and allows toggling between multiple gauges, sensors and encoders to be done easily. The SPC function gives users the ability to write up to 10,000 measured values to an internal memory and evaluate them statistically. The stored data are output via USB or RS 232 interfaces.
And with the inclusion of Heidenhain's CS-200 gauge stand with its highly polished granite surface, tight tolerances are ensured due to the well maintained shaft perpendicularity. A vacuum chuck option, consisting of a ceramic suction plate and a diaphragm pump, is available for this system to further increase accuracy by eliminating air gaps during the metrology process.
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