Torque and Spindle Motors

Servo Motors

The TK series of frameless brushless motors provide the highest torque density available today for direct drive, high performance applications.

TK Torque Motors are three phase, rare earth (Iron Neodymium Boron) permanent magnet units and reach the highest continuous and peak torque density available today.

Unlike traditional torque motors, TK units have both high torque and high speed capability and thus operate seamlessly both as spindle and rotary table motors.

The rotors use special Phase manufactured magnets with minimized loss factor allowing high speed operation with a thin isotropic rotor.

TK motors are three phase, rare earth (Iron Neodymium Boron) permanent magnet units and reach the highest continuous and peak torque density available today, together with high speed and flux control ability over a constant power range up to 10:1.

TK Torque Motors consist of stator and rotor units supplied separately suitable for direct mounting inside the machine structure.

All rotors are rigid units with mechanical, glue free magnet retention, preloaded carbon fiber sleeve for safe operation even at very high speed.

Rotor are often semi custom units to allow direct coupling to bearings, encoders, brakes.

Customized frames with integral cooling or even partial machine subassemblies with bearings and encoders are manufactured on request based on the standard frameless magnetic designs available.

Torque Motors - Made in Italy - Servo Motor
Torque Motor TK - Spindle Motor - Phase Motion Control
Torque Motors - Made in Italy - Servo Motor
Torque Motor TK - Spindle Motor - Phase Motion Control

All TK Torque Motors are designed for fluid (water) cooling on the outside of the stator for maximum performance. Conduction/convection cooling is also possible.Constant power operation (flux control) always requires water cooling.

Torque Motor code Stack [mm] L tot.[mm] Øout [mm] Øin [mm] Torque (Water Cooled) [Nm] Torque (Air Cooled)[Nm] Peak Torque
[Nm]
Nominal Speed (rpm) Max Speed (rpm)
TK.085 50 110 96 44 7,30 3,70 24,10 5000 18000
100 160 96 44 16,20 8,10 48,20
150 210 96 44 25,40 12,70 72,30
200 260 96 44 34,70 17,40 96,40
TK.110 50 125 121 43 12,50 6,30 33,20 5000 20000
100 175 121 43 26,90 13,50 66,30
150 225 121 43 41,60 20,80 99,50
200 275 121 43 56,30 28,20 132,70
TK.120 50 125 134 54 21,90 11,00 47,50 5000 15000
100 175 134 54 48,20 24,10 95,10
150 225 134 54 75,10 37,60 142,60
200 275 134 54 102,40 51,20 190,00
TK.164 50 125 173 76 48,30 24,10 93,50 4000 10000
100 175 173 76 104,70 52,30 187,00
150 225 173 76 162,10 81,10 280,40
200 275 173 76 219,90 110,00 374,00
300 375 173 76 336,00 168,00 560,90
TK.188 50 140 202 80 34,80 17,40 119,50 6000 28000
100 90 202 80 79,10 39,50 238,90
150 240 202 80 125,80 62,90 358,40
200 290 202 80 173,60 86,80 477,80
300 390 202 80 270,50 135,20 716,80
TK.195 50 160 207 76 49,50 24,80 93,50 2000 15000
100 210 207 76 108,69 54,30 187,00
150 260 207 76 169,20 84,60 280,40
200 310 207 76 230,20 115,00 374,00
300 410 207 76 352,70 176,40 560,90
TK.220 50 170 240 110 75,60 37,80 159,00 3000 14000
100 220 240 110 172,40 86,20 318,10
150 270 240 110 274,40 137,20 477,10
200 320 240 110 378,70 189,30 636,20
300 420 240 110 590,10 295,10 954,30
TK.240 50 135 249 142 111,20 55,60 216,50 3000 8000
100 185 249 142 240,00 120,00 433,00
150 235 249 142 371,30 185,60 649,40
200 285 249 142 465,90 251,60 865,90
TK.270 50 140 282 160 112,30 56,20 282,70 3000 8000
100 190 282 160 253,00 126,50 565,50
150 240 282 160 399,30 199,60 848,20
200 290 282 160 547,70 273,90 1.131,00
TK.310 50 120 310 198 215,60 107,80 373,90 500 3000
100 170 310 198 475,90 238,00 748,00
150 220 310 198 743,30 371,70 1.121,80
200 270 310 198 1.013,00 506,60 1.495,70
TK.340 50 145 358 190 242,00 121,00 407,20 2000 6000
100 195 358 190 547,20 273,60 814,30
150 245 358 190 864,70 432,40 1.221,50
200 295 358 190 1.186,90 593,50 1.628,60
300 395 358 190 1.837,00 918,50 2.442,90
TK.370 50 140 380 268 271,70 135,90 636,20 1000 4000
100 190 380 268 604,50 302,20 1.272,30
150 240 380 268 947,40 473,70 1.908,50
200 290 380 268 1.294,00 647,00 2.544,70
300 390 380 268 1.991,40 995,70 3.817,00
TK.450 50 170 465 320 468,20 234,10 916,10 1000 3000
100 220 465 320 1.033,70 516,90 1.832,20
150 270 465 320 1.613,00 806,50 2.748,30
200 320 465 320 2.196,90 1.098,40 3.664,40
TK.485 50 145 485 345 544,00 213,00 1.068,00 1000 2000
100 195 485 345 1.197,00 500,00 2.136,00
150 245 485 345 1.858,00 802,00 3.204,00
200 295 485 345 2.521,00 1.110,00 4.272,00
TK.540 50 145 548 400 712,80 356,40 1.431,40 400 1500
100 195 548 400 1.547,50 773,80 2.862,80
150 245 548 400 2.397,40 1.198,70 4.294,20
200 295 548 400 3.252,00 1.626,00 5.725,60
TK.570 50 115 578 450 745,40 372,70 1.767,10 400 1500
100 165 578 450 1.673,00 836,50 3.534,30
150 215 578 450 2.632,50 1.316,20 5.301,40
200 265 578 450 3.603,60 1.801,80 7.068,60
TK.795 50 160 815 640 1.631,10 815,50 3.365,40 200 800
100 210 815 640 3.781,20 1.890,60 6.730,70
150 260 815 640 6.063,60 3.031,80 10.096,10
200 310 815 640 8.402,10 4.201,10 13.461,40
TK.1150 50 190 1210 908 3.495,00 1.785,00 6.789,00 100 400
100 240 1210 908 7.996,00 4.281,00 13.577,00
150 290 1210 908 12.696,00 6.952,00 20.366,00
200 340 1210 908 17.457,00 9.695,00 27.155,00
TK.1340 50 190 1420 1100 4.542,80 2.271,40 9.842,30 100 400
100 240 1420 1100 10.639,40 5.319,70 19.684,60
150 290 1420 1100 17.147,10 8.573,50 29.526,90
200 340 1420 1100 23.831,50 11.915,70 39.369,20
TK.1700 50 190 1770 1420 8.113,80 4.056,90 15.946,80 100 300
100 240 1770 1420 18.951,20 9.475,60 31.893,50
150 290 1770 1420 30.480,20 15.240,10 47.840,30
200 340 1770 1420 42.301,80 21.150,90 63.787,00
TK.2000 50 260 2085 1700 8.587,40 4.293,70 23.004,10 100 300
100 310 2085 1700 20.713,90 10.356,90 46.008,20
150 360 2085 1700 34.103,80 17.051,90 69.012,30
200 410 2085 1700 48.132,40 24.066,20 92.016,40
TK.3080 50 260 3170 2760 24.318,60 12.159,30 51.035,20 100 250
100 310 3170 2760 57.331,50 28.665,80 102.070,30
150 360 3170 2760 92.790,20 46.395,10 153.105,50
200 410 3170 2760 129.340,00 64.670,00 204.140,70

Motor morphology and application guidelines

TK motors consist of:
A three phase stator, wound and impregnated (3 dips, preferred solution for high thermal cycling), or vacuum encapsulated in super high thermal conductivity compound (for low surface temperature operation), which is either built into a thin steel microframe, cylindrical, or into a metallic frame carrying the cooling chambers and coupling O-Rings on the outside and a set of tapped holes on one side (Squid type).

The microframe units are ground to h7 tolerance on the outside diameter and are machined parallel on the two stack sides. This construction is intended for interference fit or axial pressure locking.

The microframe technology maximizes the usage of space in the assembly and requires the machine body to carry the cooling cavities on the inside. It requires some care in the design of the application but results in the highest space and power density today possible.

Alternately, the SQUID frame is much simpler to use and only requires a cylindrical cavity, while motor assembly and fastening s just through a set of screws. The achieved torque density is slightly inferior to the microframe due to the radial size of the frame.

The insulation system of the motors is rated Class H (magnet wire: Class C) with reinforced insulation specifically designed for the high DV/dt typical of 600 Vdc servo drive application; the windings are equipped with three PTC sensors for protection and a KTY 84 linear temperature probe for process monitoring.

The star point of the winding is also generally available for filtering purposes. All windings are factory tested for insulation 4.5 kVdc to ground and 3.5 kVdc phase to phase, far in excess of regulation requirements.

A Permanent Magnet Rotor, with tubular, isotropic base shape, which carries the magnets on the outside periphery, protected by a preloaded carbon fiber (up to 150 m/sec) ring.

The magnets are generally high temperature, high energy FeNdB sintered magnets, Phase Motion Control manufactured with a special patented technology. They are designed for the maximum class temperature and are virtually impossible to demagnetise except in case of drive failure or improper operation. If continuous exposure to oil is forecast, special oil resistant magnets can be specified.

The rotor may be fastened on the shaft either by interference fit or by an array of axial bolts. The latter construction is preferred for high torque, low speed applications such as rotary tables. In general, the rotor inside profile is customised to fit with the needs of the machine provided the required profile is compatible with the maximum hole required by the magnetic field, and specified in the accompanying technical sheets.
For proper operation, the motors need a position sensor on the shaft (not supplied) both for field orientation and for position/speed control.
The rotor is permanent magnet type and has no primary losses, so that no rotor cooling is needed in principle. However, the inverter chopper frequency must be set high enough to ensure that the ripple current, pk-pk is less than 20% of the nominal rms current to avoid the insurgency of unacceptable, and dangerous, stray rotor loss.

Customized frames with integral cooling or even partial machine subassemblies with bearings and encoders are manufactured on request based on the standard frameless magnetic designs available.
The rotors are supplied not balanced; high speed operation requires dynamic balancing when assembled on the application shaft.

Depending on their geometry and magnetic circuit, TK motors can be divided into three main branches:

Thin ring, large diameter motors for high torque, low speed (torque motors)

Typical applications:

  • Rotary tables for NC machine tools, often with turning capacity
  • Indexers for transfer machines
  • NC machine head orientation
  • Large rotary tables (glass, packaging, assembly)
  • Carbon fiber deposition machinery
  • Direct drive of mills (concrete, ceramics, rubber
  • Large low speed generators (mini hydro, wind power)
  • Metal forming: electric press and bending
  • Direct drive plastic injection machines

In all these applications, direct drive eliminates play and removes the need of an accurate mechanical gearbox, which in turn would limit the accuracy and the dynamic performance of the system. Mechanical brakes-dividers are unnecessary. The table accuracy is the accuracy of the encoder system. The system is thus extremely simple, flexible and reprogrammable.
The removal of the transmission system and of its backlash and elasticity results in control bandwidth up to 250 Hz, so that a positioning cycle can be completed with great accuracy within a few msec with advantage on the machine cycle time. To ensure adequate servo performance in direct drive high accuracy, high stiffness applications such as indexing and rotary tables in NC machine tools, the sensor must be sinusoidal so that the drive may interpolate the actual position with a resolution at least ten times greater than the required accuracy. Additionally, the sensor fastening or spring mount must have intrinsic resonance frequency above 2000 Hz not to limit the overall system performance.

Spindle motors for mills and lathes

long and thin motors, brushless with flux control ability, medium to high speed, high power density, suitable for heavy machining or control of large inertia loads for spool winding/unwinding. The TK motors have currently the highest power density and allow the manufacture of electrospindles with torque rating hiterto unattainable, in the range of several thousand Nm while reaching high speeds in the thousands of rpm. Spindle type motors are anyway high performance servo motors so another emerging application area is very short cycle actuation. Recent application are in direct drive of the ram of high speed turret punching press with stroke rates in excess of 300 strokes/min, or fast, heavy indexing in wire frame welding machines.

Typical applications:

  • Power lathes for automotive,
  • Spindle motors for mills and high speed machining centers
  • Wire grid manufacturing

Tube motors, small diameter, for multiple spindle units

Typical applications:
  • High speed/power motors where lateral (pitch) space is limited
  • Multiple drilling heads
  • Swiss type lathes
Standard size of terminal cables vs nominal motor current
PTFE insulation, 2500 Vac, L=500 mm
Nominal current Wire size
In < 15 Arms 1.22 mmq = AWG 16
15 Arms <= In< 25 Arms 2.97 mmq = AWG 12
25 Arms <= In< 45 Arms 8.6 mmq = AWG 8
45 Arms <= In< 82 Arms 15 mmq
82 Arms <= In< 110 Arms 25 mmq
110 Arms<=In< 200 Arms 50 mmq

How to choose the optimal TK motor?

First, define the technical feasibility of the application. In general, all motors share the same physical limitation, that is, the ability to generate “airgap thrust”, i.e. a sideways thrust between stator and rotor which is linear thrust in linear motor, and becomes a torque when the motor is round. The amount of thrust per unit area depends on motor technology but is fundamentally limited by the properties of the materials (magnets, copper, steel) used in the motors. PM technology offers the highest specific thrust available today, and this value is gradually increased as the technology improves. Many factors (cooling conditions, size, airgap thickness, linear speed etc.) affect this value which should only be used as a rough guideline. Tk rotary motors and Wave linear motors are characterised by a peak thrust around 8000 N/m2, continuous thrust with water cooling ~ 5500 N/m2.

The thrust limitation explains why it is always appropriate to use the maximum diameter available to maximize output torque. In general if a motor is scaled in diameter, torque is scaled with the square of diameter, while it scales only linearly in length. Consequently, to verify whether a new application is feasible at all, if the torque availability is expected to be a limitation, the maximum diameter available should be determined compatibly with physical limitation and maximum peripheral speed (values below 150 m/sec pose no problem) and the airgap surface can then be evaluated. This would give a rough estimate of motor length and therefore indicate whether the application is feasible or not.

Large rings with very limited axial length are the most efficient solution for high torque low speed applications, and they have the additional advantage of not needing separate bearings as they can be generally carried by the same bearings of the load. However, inertia scales with the cube of diameter, so where the inertia is the dominant load, long and thin motors are more appropriate. A typical example is the direct drive of the ram of high speed punch presses, in which motion is reversed over 300 times/min, or in high speed flying shears; in this case, tubular, water cooled TK motors provide the highest performance solution.

Spindle drives generally demand both high torque and high speed but the diameter is generally restricted, so they tend to be long and thin. Airgap hole diameter to length ratios up to 1:3 are routinely manufactured. In this case, the Phase PM magnet technology allows the manufacture of extremely thin stators and rotors which are particularly useful in multispindle applications.

Spindle PM motors manufactured with the high frequency Phase magnetic technology can operate both in constant torque and constant power mode. The constant power range, depending on the type, can exceed 10:1 although this is generally limited by the ability of the drive selected to control a deep deflux range.

When compared to AC Induction spindle motors, the PM motor design offers:

  • Rated torque approximately double in the same size
  • Larger shaft compared to the outer diameter
  • Loss only limited to stator, rotor is “cool” so that bearings can operate more accurately and reliably
  • Solid, “mechanical” rotor (non laminated) which guarantees balancing stability
  • Wide constant power control range (up to 10:1) without tap change
  • Free from radial flux which may generate currents in the bearings

In the Phase TK technology, there is no fundamental physical difference between torque motors and spindle motors; they have the same smoothness and high bandwidth necessary for direct drive indexing and contouring operation, so that milling and turning operations on the same motor are now possible.

There is, however, a fundamental difference between PM and induction spindle drives. In the induction technology, power is used to magnetize the motor (at low speed, high torque) thus resulting in limited output torque available; flux reduction is easily obtained by just reducing the magnetizing current.

Thus the motor is “hot” at max load, and “cool” at no load. PM motors, conversely, derive the field from high energy permanent magnets, so that no power is required to build the motor field and more power can be devoted to torque generation. When the flux must be reduced, however, power must be applied just to lower the field so that PM motors at high speed need some current even at no load.

A typical power and torque curve versus speed is shown in Fig. 1 for a combined torque/spindle motor with 570 mm diameter, 100 mm axial length; in Fig. 2, the motor temperature at no load and full loads are displayed. It can be observed that above the “knee speed” i.e. the speed of transition between constant torque and constant power operation, the motor temperature becomes progressively independent of motor load.

Mechanical Assembly, airgap control and magnetic attraction

Another useful feature of PM technology is the ability to operate with a wide airgap, up to several millimetres in the larger motors. This feature can be useful in machines with important deformations, such as plastic injection press or impact hammers. As a standard the airgap is in the order of 1 mm, radial, and this generally enables designs in which the motor rides on the machine supports without need of separate bearings.
The magnetic flux in the rotor generates radial attraction forces.

These are perfectly balanced only if the rotor sits in the center of the stator, and increase with eccentricity. In practice, this is equivalent to a “negative stiffness” which must be compensated by a much higher positive stiffness in the bearing system. The attraction data can be supplied on demand, the order of magnitude is shown in the graph in Fig. 3, for a 1000 Nm, 370 mm diameter, 105 mm long torque motor with a 1 mm radial airgap.

High torque electric motor, High torque servo motor, High torque low rpm electric motor, Low speed high torque electric motor, High torque low rpm ac electric motor, Small high torque electric motor, High torque brushless electric motor, High torque low rpm motor, High torque low rpm electric motorHigh torque low rpm ac electric motor, Compact High torque electric motor, Ultra high torque motor, High torque dc motor, 12v dc motor high torque, 12 volt dc motor high torque, 12v dc motor high torque low rpm, 24v dc motor high torque high speed …