Measure spindle extension on high speed machine tools.
With milling and grinding machines, loss of accuracy can be
a real problem, especially if high accuracy is required for
machining of very precise components. Unwanted thermal
expansion of the spindle can occur if the CNC system does
not actively compensate for these temperature increases. If
the spindle expands by even a small amount, the machine
tool head can cut too deep.
By working closely with machine builders and spindle manufacturers,
Micro-Epsilon has developed a special sensor system, the SGS
(Spindle Growth System), for solving this issue, which also enables
machine tool operators to change the spindle without having to
re-calibrate the sensor and electronics.
The sensor, Micro-Epsilon's eddy current eddyNCDT sensor, is
accurately measures any Z-axis expansion of the spindle. The system
enables the active compensation of the axial spindle extension via a
CNC machine tool. The result is a much more accurate milling or
The SGS sensor system was originally developed for Steptec, a
Swiss manufacturer of machine tool spindles. The sensor is based
on Micro-Epsilon's standard eddyNCDT sensor but has a special
aluminium, more compact housing and is rectangular in shape
rather than cylindrical.
The SGS measuring system uses the eddy current measurement
principle. The sensor is controlled by electronics with a digital signal
processor (DSP). All sensor-specific data is stored on the sensor
itself, using an embedded EEPROM chip. After changing the spindle,
the system is ready to run
The sensor has very high temperature stability of ±0.01% FSO/°C.
Resolution is less than 0.5µm and the sensor controller measures
just 175mm x 110mm x 45mm. The controller housing is made from
a heavy duty cast aluminium, which gives it excellent protection
against electromagnetic noise and dirty environments (IP67).
Micro-Epsilon normally supplies its SGS system to spindle
manufacturers, for integration, but can also supply direct to the
machine builder if required.