Technical datasheet

Description of Multi Head Scanning Possible sources of errors

On a detailed view of possible sources of error on a rotary axis one encounters the following errors: A. Systematically, repeatable errors per revolution• Eccentricity from measuring flange with respect to the axis of rotation ? Grating errors of the measuring scale as deviation from an ideal grating ? Run out errors from the bearing B. Coincidental errors ? Backlash of the bearing ? Load-sensitive deformation Since the systematically errors specified above are in practice not completely avoidable, we present an economic compensation possibility:

Multi Head Scanning- with MHS-21x

The AMO rotary encoder MHS-11x is designed for high accuracy applications, where precision bearings are used which are backlash free (pre-tensioned in mounting). Therefore, most of the measuring errors are systematic and repeatable, and the non-repeatable errors for the majority of applications can be neglected. The measuring system consists of a measuring flange, 2 reading heads and an evaluation electronics box and as shown on page 5. During a rotary movement of the measuring flange the MHS-21x reads position data from both heads continuously and evaluates a corrected position signal on the system output. Consequence: The eccentricity error is completely eliminated and the influences of systematic errors is reduced by a factor of 2 The great advantage of the MHS-11x is that also changing eccentricity during the machining process (i.e rotary tables, milling heads which gets different radial loads) is compensated.
2 von 12 Technical data are subject to change without notice DB_MHS-2xx_EN_20080220.doc