Ultra-Precise Aerostatic Tool Spindle with Auto Collet Tool Clamping

Description and function

Our ultra-precision tool spindle model ASD-Cx (x = tool shank diameter) combines Ultra-Precision, speed, robustness, and CNC functionality to machine optical and high-precision parts at high-speed on CNC machine tools. All this includes an auto collet tooling system, a high-resolution rotary encoder, a high-efficient thin-film liquid cooling, and a standard-size steel housing.

As a result, and for the first time, the user of CNC machine tools now gets the opportunity to mill and grind optical and high-precision parts to a quality only known from Ultra-Precision machine tools without scarifying CNC functionality and productivity. On the other hand, the user of Ultra-Precision machine tools can now add high material removal rates, automated tool change, and a significant increase in automation to Ultra-Precision machining.

… according to our slogan, “Ultra-Precision meets Industrial Grade”

Like our ASD-H25/A, our ASD-Cx is available with high-pressure aerostatic technology, also known as UASD-Cx. Running on 20-30 bar bearing supply pressure, the high-pressure aerostatic version UASD-Cx provides three times the load capacity in the axial and radial direction for a significantly increased robustness.


Body Diamater:

Nominal Speed:

Tool Interfacee:

Available clamping diameters:

Motor options:

Rotary Encoder:

Tool change system:

Spindle cooling:

Bearing system:


Accuracy, dynamics:


Spindle connectors:

100 mm (custom flange option on request)

60,000; 80,000 or 100,000 rpm (other spindle speeds on request; max. 100,000 rpm)

automatic direct tool shank clamping (precision collet)

1/4″, 1/8″, 6 mm, 4 mm, 3 mm

permanent magnet synchron, 2 poles, 3 phases

80 lines 1 VSS SinCos with zero-flag

pneumatic, taper cleaning air

thin-film liquid cooling

aerostatic, 6 – 10 bar (ASD-Cx)

high-pressure aerostatic, 20 – 30 bar (UASD-Cx)

dynamic tool run-out < 0,5 µm)

Error-motion (Error-Motion) < 30 nm

radially oriented

*) all values taken at 20 bar bearing air supply pressure

*) field weakened operation

  • Bespoke Flange Options

Custom spindle flanges with a shrink fit to the spindle body allow a reliable and straightforward integration of our spindle products into your machine design. Let us know your spindle stock design, and we will take care of the design work and manufacture the right spindle flange.

Contact us about your spindle connections.

  • Interchangable Collet

Our in-house designed and manufactured collet systems offer a unique tool run-out of under 0.5 micron. The collet is adjusted to the spindle to get such low run-out values.
On request, the spindle can come with interchangeable collets of different sizes:

  • 6 mm
  • 4 mm
  • 3 mm
  • 1/4″
  • 1/8″
  • ASD-H25/A and ASD-Cx – At a Glance
  • Spindle Operation below Spindle Resonances from Standstill to Top Speed

Our patented bearing technology allows bearing stiffnesses no other aerostatic technology can meet with. The increase in stiffness with speed due to centricugal load and temperature was picked up for the optimization of the rotor dynamics of our spindle products and guarantees a resonance-free operation of all of our spindle products from standstill to top speed. Here the analytically optimized shaft-bearing design makes sure that the spindle speed (= rotation frequency) always stays far below any shaft bending or rigid mode spindle critical frequencies. If not the operation of a spindle at this speed would result in tremendously high vibrations and tool run-out.

The graph to the right was taken with a high-resolution capacitive gauge measuring against the spinning tool. The gauge not only measures the run-out, but also the vibration of the tool. An FFT analysis can be done for any spindle speed resulting in a resonance spectrum with spindle speed and the residual shaft imbalance as exciting force. This spectrum now includes the exciting frequency (=spinning frequency) as well as any system natural frequency. Doing this at every spindle speed leads to a 3D waterfall-chart with spindle speed as additional dimension. As the amplitude is of no interest at this point it is easire to look top-down where the light aereas now represent peaks (=resonances).

As can be seen on a measurement with our ASD080H25 with a max. speed of 80.000 rpm the exciting frequency (= spinning frequency) never get close to any resonance frequency. For the user this means that at what speed ever he uses our ASD080H25 or any other model spindle speed never is close to a system natural frequency where it is usual for any other spindle on the market. This makes sure that, at what ever speed it is used, vibrations and tool run-out is low.

  • Dynamic Tool Run-Out and Vibrations with Spindle Speed

The bearing-shaft design of our spindles are strictly optimized for best shaft dynamics. Means, a light and stiff shaft design combined with high bearing stiffnesses for a resonance-free operation from standstill to top speed.

In combination with our highly specialized production technology spindle taper a run-out of less than 50 nm can be guaranteed.

As a result the user not only gets a robust high-speed spindle with a load capacitiy better than with any other aerostatic high-speed spindle, he also gets a dynamically neutral spindle operation over the entire speed range with a dynamic tool run-out of better 0.8 micron.

  • Error Motion

Definition: The value of the so called Error-Motion includes any synchronous and asynchronous spindle error from the theoretical perfect axis of rotation, but without the fundamental (fundamental = run-out)

To perform such a Spindle Error Analysis (SEA) a precisely ground ball is attached to the shaft and one or more gauges measure the radial/axial motion of it. As the roundness of such a SEA-ball (artefact) is much worse than the spindle error itself it becomes clear that an error-separation of spindle and artefact has to take place. This can either be done with a reversal FFT Method where the artefact and the probe has to be rotated by 180° for a second measurement or a multi-probe complex FFT analysis.

Levicron has developped mathematical methods and test benches for the multi-probe measurement of Spindle Motion Errors. As rotation speeds for Levicron products exceed the technical capability of any commercially available solution Levicron developped tailor made hard- and software to verify their products Error-Motion specifications. Our tool spindle models ASD-H25, ASD-H25A and ASD-Cx are specified and verified with a Spindle Motion Error of less than 30 nm.

  • Axial Shaft Growth and Spindle Soak Time

As it can be seen from the graph to the right the thin-film liquid cooling and the cartridge deisgn of our tool spindles ASD080H25, ASD080H25A and ASD080Cx result in a spindle soak time from cold and standstill to top speed and warmed through of less than 3 minutes. For the user this means that after 3 minutes the spindle doesn’t change its properties, doesn’t matter for how long I use it at top speed. Not only that this period is 5-20 times faster than with any other spindle solution, the user also can use the spindle at 80.000 rpm for an unlimited period of time.

The optimized design also compensates for axial growth. Where the centrifugal load on the shaft causes a reduction on length, the increase in temperatur causes an increase. That’s why a total axial shaft growth of less than 5 micron from cold and standstill to 80.000 rpm and warmed through could be achieved. With our ASD060H25 and ASD060Cx and 60.000 rpm even a value of under 3 micron can be specified.