ASD-H25 / ASD-H25A

Ultra-Precise Aerostatic Tool Spindle with automated HSK-E25 tool interface

Our ultra-precision tool spindles ASD-H25 (with radial spindle connectors) and ASD-H25A (with axial spindle connectors) combine Ultra-Precision, speed, robustness and CNC functionality to machine optical and high-precision parts at high-speed on CNC machine tools. This includes a spring-less automated HSK-E25 tool interface, a high-resolution rotary encoder, a high-efficient  thin-film liquid cooling, tool clamp status monitoring and a standard size steel housing.

As a result and for the first time ever the user of CNC machine tools now get the opportunity to mill and grind optical and high-precision parts to a quality only known from Ultra-Precision machine tools without scrifying CNC functionality and productivity. On the other hand the user of Ultra-Precision machine tools now can 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”


Body Diamater:

Spindle Speed:

Tool Interface:


Constant Motor Torque, High-Torque Option (CNC):

Constant Motor Torque, Ultra-Precision Option (UP):

Rotary Encoder:

Tool Clamp Monitoring:



100 mm (Flange option on request)

60.000, 80.000 oder 90.000 Rpm (other speeds on request)

HSK-E25, spring-less, pneumatic

Permanent Magnet Synchron, 2 Poles, 3 Phases

0.66 Nm

0.35 Nm

80 Cycles (Lines), 1VSS, incl. Zero-Flag

3 x digital

400 mm (ASD-H25A), 435 mm (ASD-H25)

16 kg

ASD060H25/A ASD080H25/A ASD090H25/A
General Body Diamaeter [mm] 100 100 100
Length [mm] 435/400 435/400 435/400
Weight [kg] 16 16 16
Speed [krpm] 60 80 90
Motor "High-Torque", max. 400 V Type [-] 3 Phases, Synchron 3 Phases, Synchron 3 Phases, Synchron
Constant Torque [Nm] 0,66 0,66 0,66
Poles [-] 2 2 2
Max. Phase Voltage [V] 320 380 400
Nominal Current [A] 10 10 10
Peak Current [A] 20 20 20
Shaft Power [kVA] 4,1 5,5 6,2
Motor "High-Torque", max. 208 V Type [-] 3 Phases, Synchron 3 Phases, Synchron 3 Phases, Synchron
Constant Torque S1 [Nm] 0,66 0,66 0,66
Poles [-] 2 2 2
Max. Phase Voltage [V] 320 380 400
Nomial Current [A] 10 10 10
Peak Current [A] 20 20 20
Shaft Power [kVA] 4,1 5,5 6,2
Motor "Ultra-Precision", max. 400 V Type [-] 3 Phases, Synchron 3 Phases, Synchron 3 Phases, Synchron
Contant Torque S1 [Nm] 0,35 0,35 0,35
Poles [-] 2 2 2
Max. Phase Voltage [V] 300 340 360
Nominal Current [A] 5 5 5
Peak Current [A] 11 11 11
Shaft Power [kVA] 2,2 2,9 3,3
Motor "Ultra-Precision", max. 208 V Type [-] 3 Phases, Synchron 3 Phases, Synchron 3 Phases, Synchron
Constant Torque S1 [Nm] 0,33 0,33 0,33
Poles [-] 2 2 2
Max. Phase Voltage [V] 300 340 360
Nominal Current [A] 5 5 5
Peak Current [A] 11 11 11
Shaft Power [kVA] 2,2 2,9 3,3
Rotary Encoder Type [-] incremental incremental incremental
Cycles (Lines) p.r. [-] 80 80 80
Signal A/B [-] SinCos, 1 VSS SinCos, 1 VSS SinCos, 1 VSS
Zero Flag [-] yes (an./dig.) yes (an./dig.) yes (an./dig.)
Bearing System Supply Pressure [bar] 6 - 10 6 - 10 6 - 10
Air Purity, ISO [-]
Radial conc. Stiffness at Spindle Nose, static [N/µm] > 40 > 30 > 20
Radial Load Capacity at Spindle Nose, static [N] > 330 > 300 > 280
Axial conc. Stiffness [N/µm] > 60 > 40 > 30
Axial Load Capacity [N] > 600 > 550 > 500
Stability and Precision Shaft Taper Run-Out [nm] < 50 < 50 < 50
Error-Motion [nm] < 30 < 30 < 30
Dyn. Run-Out at Tool *) [µm] < 0,5 < 1 < 1,2
Thermal Soak Time [min] < 3 < 3 < 3
Axial Shaft Growth [µm] < 3 < 5 < 6

* – if used with tool Holder type Levicron UTS-25

  • Radial Spindle Connectors (Standard)

Together with the modular spindle design our ASD-H25 with radial spindle connectors offer a serviceability better than any other tool spindle and thus guarantees flexibility at low costs.

  • Axial Spindle Connectors (ASD-H25A)

With 100 mm in diamater over its entire length our ASD-H25A with axial spindle connectors allows its use in closed z-stocks that only allow an installation from the bottom up. If the spindle is planned to be used in an open spindle stock or in one that is assessible from both sides we recommend the option with radial connectors (ASD-H25)

  • Bespoke Flange Options

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

  • Download Product Catalogue

Download and save the PDF catalogue of our ASD-H25 and ASD-H25A for detailled product information.

  • 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.

  • Tool Clamp – and Tool Clamp Repeatability

With our highly specialized production a spindle taper run-out of better 50 nm is guaranteed. With the same manufacturing technology our HSK tool holders UTS-x are machined for which we guarantee a tool run-out of less than 0.8 micron and a balancing quality of G0.3 mm/s at 60.000 rpm.

The upper right picture shows a tool run-out measurement of our ASD-H25 at a customer site and at 185 mm in front of the spindle nose. A value of below 0.5 micron confirms the quality and combination of our HSK tool interface and spindle taper.

As a standard test the tool change repeatability of every spindle is tested by our 4 x 90° reversal balancing test at top speed (lower picture). For this the residual imbalance of one of our UTS-x HSK tool holders is measured at 0°. Then the resdidual imbalance is measured after the holder was rotated by 90° against the shaft. This done three times. The distance from the midpoint of the resulting square to one of its corner represents the tool clamp repeatabilty where the imbalance is defined as an eccentricity of the tool holder mass. With this method we can guarantee a tool clamp repeatability of less than 0.2 micron.

  • 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.