Active Machining System (AMS)

AMS System controls cabinet connected to a standard lathe.

Active Machining System (AMS) is the most responsive and accurate fast tool servo system on the market specifically designed to turn the non-round skirts of pistons. AMS is synchronized to the rotation of machine tool spindles. The solid-state position of the tool is controlled by the elongation of an extremely rigid bar of TdVib Terfenol-D. The dynamic mass of the system has purposefully been kept low in order to minimize the accelerations seen in the machine tooling plate. This combination of rigidity, speed, and mass makes the AMS system the ideal choice for manufacturers of large volumes of pistons.

The AMS’ unique combination of attributes make it ideal for rapidly position a cutting insert for turning elliptical pistons. The basic AMS system is capable of machining ovals at speeds up to 6000 RPM. AMS was originally designed for the small piston manufacturing industry. However, it is also suitable for other industrial pistons such as automotive, off-road, agriculture, and marine diesel pistons. Other potential areas of application include cam machining, butterfly valve disks, diamond-turning contact lenses and other glass lenses, and non-round boring (for example, wrist pin holes in pistons or connection rod bearings). Please contact us to determine if your application is suitable for AMS technology.

Key Benefits of AMS

Long Life – only solid-state moving parts means nothing to wear out – more up time

Repeatability – solid state motion prevents backlash – produces more accurate parts

Flexibility – ovality and profile can be varied along the length of the part; software tables provide maximum flexibility to incorporate the latest part design – no master cam to grind in

Rigidity – tool position is extremely rigid due to the solid state driver meaning AMS is able to handle interrupted cuts without vibrating—thereby increasing the quality of surface finish.

Speed–Terfenol-D has been used to actuate devices at over 20,000 cycles per second. In comparison, machining pistons requires relatively slow operation at 200 cycles per second. The fast response of the Terfenol-D provides sufficient bandwidth to reject disturbances from interrupted cuts arising from voids in the castings and wrist pin axis “windows” designed into the piston, thereby giving excellent surface finish at production spindle rates.

Reliability– The mechanism that generates the changes in shape of the material is “cast in” to the alloy at the time of manufacture and does not degrade or wear out as other technologies. Billions of operation cycles have demonstrated reliability of Terfenol-D and the AMS system.

Basic Model Features

  • Magnetostrictive Actuator/Tool holder with feedback (air cooled at 15 psi)
  • Tool centerline from mounting surface 55mm
  • Left hand holder for Kennemetal TPGM-21 or equivalent insert (insert not included)
  • Single spindle speed
  • Single ovality with variable magnitude (linear interpolation)
  • Profile with variable magnitude (linear interpolation)
  • Z-axis inferred from position and feed rate
  • Spindle encoder synchronization with angle adjustment
  • Temperature Compensation
  • Nema Class 12 electronics and enclosure
  • Operator interface software”



Accuracy:± 1.1 um + 2% of stroke
Repeatability:1.1 um + 2% of stroke
Spindle speed:Selectable between 1500 RPM and 6000 RPM, +/- 200 RPM
Maximum total stroke:640 um
Maximum dynamic stroke:350 um
Maximum thrust:2670 N
Tool Axial Stiffness:14.9 MN/m

Mechanical (Tooling Insert)

IC:0.250 inch
Thickness:0.094 inch
Hole Diameter:0.110 inch
Relief Angle:11 degree minimum (Insert holder generates 10 degrees of rake)
Suggested insert:Kennemetal TPGM-21

Mechanical (Actuator)

Mass:20 kg
Dimensions:See drawing


Control Cabinet:208 Volt, 20 ampere, 3 phase, 50-60 Hz
Spindle Encoder:RS422 Protocol4096 pulses per revolution using quadrature Index pulse
Communication Channel:M-code programmable SPDT relay or optoisolator


AMS Options

The AMS system can be customized to fit specific needs of different customers. Some available options include:

  • E-Stop Interface
  • Multi-channel I/O – provides system status to host: Ready, Busy or Fault
  • Discrete spindle speed selection other than 3000 RPM
  • Variable speed to 6000 RPM (stroke reduced linearly from 3000 to 6000) – 50 ft. cable
  • Multiple ovality
  • Z-axis encoder positioning (may require lathe modification)
  • NURBS interpolation instead of linear interpolation for profile and ovality magnitudes
  • Custom mounting configuration or other specialized interface engineering
  • Larger or smaller actuators for increased or decreased stroke requirements
  • Remote network connections for diagnostics and upgrades
  • Multi-spindle system
  • Single spindle, dual actuators for rough and final machining on same pass

Additional options may be available upon request.

Support & Warranty

Installation and setup will be completed by a factory representative. After installation, one additional full day is required to complete operator training on hardware and software. Additional training is available both on site and at the factory. Special engineering on site can be completed for equipment retrofit.

Each AMS System comes with a one year parts and labor warranty, assuring a unit free from manufacturing defects.

An extended service and maintenance agreement is also available.

 AMS Service and Maintenance Agreement 

Have questions or want a quotation?

Contact TdVib for a quotation on the quantity and configuration needed. Or work with us to optimize performance and cost for your application


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