Inspection System Combines Length Gage, DRO

Heidenhain’s inspection system combines a Certo length gage, which is capable of a large measuring range including high-accuracy, nonometer-level measurement, with an ND 287 digital readout (DRO) equipped with Statistical Process Control (SPC). Common applications for this system are inspection of parts with tight tolerances and gage block calibration.

The length gages measures from 0 to 25 mm at ±0.1-µm accuracy/±0.03 µm after error compensation, and 0 to 60 mm at ±0.01-µm accuracy/ ±0.05 µm after error compensation. Error compensation is handled and stored by the DRO in conjunction with manual input of values from the accuracy chart included with each length gage. The gage is composed of a low thermal growth material, Zerodur, for the glass scale and an invar shaft in order to decrease thermal effects. Also, a graduation and reference mark are imprinted onto the glass scale, so drifting, as seen in LVDT technology, is nearly nonexistent, the company says.

The DRO can accommodate as four inputs with varying interfaces, and it allows toggling between multiple gauges, sensors and encoders. The SPC function gives users the ability to write as many as 10,000 measured values to an internal memory and evaluate them statistically. The stored data are output via USB or RS 232 interfaces.