Renishaw's Signum encoders, with RESM ring, non-contact format, large through-hole, high accuracy and rugged IP64 sealed readhead, are said to be highly suitable for use within machine tool rotary axes. Furthermore, the latest models feature the new Si-FN interface that adds Fanuc serial communications.
Designed for use in gear-driven and direct-drive rotary axes, the Si-FN interface provides Fanuc serial communications direct from the encoder for higher performance and easier connectivity. Three resolution options are offered: Normal has 20-bit resolution (0.0003 degree) and speeds up to 4500 rev/min; High Type A has 23-bit resolution (0.000043 degree); and High Type B interfaces provide up to 26-bit resolution (0.0000054 degree) for the highest precision, while still being capable of 600 rev/min.
In common with the rest of the Signum range, the Si-FN interface features advanced signal processing electronics that apply automatic gain control, balance control and offset control, to output signals of high reliability and fidelity. The result is claimed to be the best sub-divisional error (SDE) in its class: the SDE of the diameter 209mm Si-FN system is only +/-0.08 arc-seconds, which is said to be five times better than competitive optical encoders and more than ten times better than competitive magnetic or inductive encoders.
As well as providing finer resolutions, High Type A and High Type B Si-FN variants also feature filtering electronics for even greater signal purity, resulting in a factor-of-two improvement in velocity ripple. Positional stability (jitter) is also improved.
Si-FN interfaces with Fanuc serial communications can be used with standard Signum read heads and standard RESM rings of 52, 104, 209 or 417mm diameters. This allows the machine or rotary axis builder to easily select Si-FN as a modular upgrade option.
All position processing occurs in the Si-FN interface, so high-resolution and high-speed combinations are possible without requiring unfeasibly high-frequency signals as would be necessary with traditional A-quad-B digital quadrature. Serial communications also provide exceptional reliability in noisy environments, especially when combined with Signum's double-shielded UL-approved cable.
All Renishaw encoders can connect via USB to a PC, where software can be used for set-up and real-time system diagnostics, even when in full servo loop control. Moreover, the Si-FN adds a fully-functional DRO (digital readout) for further diagnostics.
For more information, visit www.renishaw.com
"