New sealed linear encoders with steel measuring standard
HEIDENHAIN has revised its product range of high-accuracy sealed linear encoders of the LF series in slim-line and full-size versions with significant improvements with regard to accuracy and reliability. In addition to applications on linear motors, these new models are especially well suited for position encoding on grinding machines, jig boring machines and other precision machine tools.
To ensure both high accuracy and dynamic performance of machine tools with direct drives, the position encoders must feature sufficiently high resolution and repeatability in order to ensure exact velocity control even at slow traversing speeds. Linear encoders that generate a high-quality position signal with only small interpolation error are therefore indispensable for this task. Here the HEIDENHAIN encoders of the LF series based on a photoelectric interferential scanning principle are particularly attractive. From a grating period of 8 µm, the encoders generate scanning signals with a signal period of 4 µm. These scanning signals are largely free of harmonics and can be highly interpolated. On the revised LF 185 and LF 485, the position error within one signal period is typically smaller than ± 0.04 µm. This is equivalent to less than 1% of the signal period.
The measuring standard, which is produced with the SUPRADUR method, is applied to a steel substrate. This provides the encoder a defined thermal behavior that is equivalent in its coefficient of linear expansion αtherm ~10x10-6K-1 to most of the materials used in machine tool manufacture. The large scanning surface of the proven single-field scanning principle makes the encoders largely insensitive to local contamination.
The linear encoders LF 185 and LF 485 are also characterized by their high rigidity in the measuring direction. This is a very important prerequisite for its high-quality path accuracy on a machine tool. In addition, the low mass of moving components contributes to their excellent dynamic behavior.
For years now, HEIDENHAIN sealed linear and angle encoders have been the product of choice for precision machine tools wherever stringent requirements for accuracy, reliability and productivity must be met.