Magnetic Modular Encoders

The robust ERM magnetic modular encoders are especially suited for use in production machines. Their large possible inside diameters as well as the small dimensions and compact design of the scanning head predestine them for:

  • Magnetic Moduler encoder from HeidenhainThe C axis of lathes
  • Spindle orientation on milling machines
  • Auxiliary axes
  • Integration in gear stages

The signal period of approx. 400 µm and the special MAGNODUR procedure for applying the grating achieve the accuracies and shaft speeds required by these applications.


C axes on lathes are typically used for the machining of bar-stock material. Here the graduation of the ERM modular encoder is usually on a diameter that is twice as large as the workpiece to be machined. The accuracy and reproducibility of the ERM also achieve sufficient workpiece accuracies for milling operations with lathes (classical C-axis machining).

Measuring Standard

HEIDENHAIN encoders incorporate measuring standards of periodic structures known as graduations. Magnetic encoders use a graduation carrier of magnetizable steel alloy. A write head applies strong local magnetic fields in different directions, so that a graduation consisting of north poles and south poles is formed with a grating period of 400 µm (MAGNODUR process). Due to the short distance of effect of electromagnetic interaction, and the very narrow scanning gaps required, finer magnetic graduations are not practical.

Heidenhain Magnetic Modular Encoders