Technical Information
Lead screws parameters
Resolution (travel/step)
A lead screw combined with a stepper motor can achieve a positioning with a resolution of 10μm.
The resolution of the position depends on the pitch and number of steps per revolution:
P = Ph n
With Ph the pitch of the screw and n the number of steps per revolution of the motor.
Driving the motor with half-stepping or microstepping will improve the resolution up to a certain extent.
The resolution must be balanced with another parameter:
the precision.
Precision
The motor step angle accuracy is one parameter, together with the axial play between the nut and the lead screw, infl uencing the precision of the linear displacement. It varies between ±3 and ±10% of a full step angle depend-ing on the motor model (see line 9 on motor datasheet) and remains the same with microstepping. It is however not cumulative.
Axial play
An axial play up to 30μm is measured with optional nuts offered in this catalogue. However, it is possible to negate the axial play by implementing a preloading system in the design of the application (for instance with a spring mechanism).
The “zero” axial play between the lead screw and motor housing is ensured thanks to a preload of the motor ball bearings (in standard confi guration: spring washer on rear ball bearing). An axial play up to 0.2 mm will occur if the axial load on the lead screw exceeds the ball bearing pre -load.
This does not cause any damage to the motor and is reversible. This occurs only while pulling on the shaft.
On request, customization can overcome this limitation.
To avoid irreversibly damaging the motor, the maximum axial load should always remain under the maximal push force the motor can generated with a mounted lead screw.
Backdriving
Backdriving the motors while applying an axial load on the lead screws is impossible. The pitch vs. diameter ratio does not allow it.
Force vs speed curves
The force that a linear system can provide depends on the type of screw and stepper motor selected. Torque vs speed curves for each solution are provided in this catalogue.
Those curves do already consider a 40% safety factor on the motor torque as well as a conservative lead screw effi ciency in the calculation.
Tip for bearings
Ideally, the application should handle radial loads and the lead screw only axial loads. If it is not the case, it is possible to get lead screws with a tip suitable for bearing at its front end in order to handle radial loads. With this con -fi guration, a special care to the alignment of the motor and bearing must be paid to not deteriorate the thrust force achievable. Optional mating ball bearings are avail -able in the dedicated datasheet for options.
Nut
Optional nuts offered in this catalogue are shaped with a fl at in order to prevent its rotations in the application.
Alternatively, tapped holes on the application are a convenient solution since metric taps are readily available.
1,2 0,25
M1,2 x 0,25 x L1
Linear actuation for positioning tasks
Lead Screw
Series
Order code (no bearing tip) Order code (with bearing tip)
Ordering information L1 (mm) =
Nominal diameter Pitch
Material Stainless steel
LSM1,2_PCS_NEW.indd 1
Features
Stepper motors can be used for more than just a rotation.
When combined with lead screws, they provide a high accuracy linear positioning system that provides the benefi ts of a stepper (open loop control, long life, high torque density, etc.).
The lead screws available on stepper motors are all based on metric dimensions (M1.2 up to M3) and specifi cally designed to be assembled with stepper motors. The technique used to produce the thread ensures a very high precision and consistency of quality. A large choice of standard lengths is available from stock and customiza-tion is possible on request.
Such a combination is ideal for any application such as requiring accurate linear movement or lens adjustment (zoom, focus), microscope stages or medical syringes.
Benefi ts
■ Cost effective positioning drive without encoder
■ High accuracy
■ Wide range of lead screws available
■ Short lead time for standard length
■ Flexibility offered by optional nuts and ball bearings
■ Custom length on request
AM1524 Motor series 2R Bearing type 0075 Winding type
Product code
Lead Screws and Options
M3 Screw type 15 Length (mm)
AM1524 2R 0 0 7 5 5 5 M3 x 15
Lead Screws
1 Stepper motor
2 Lead screw
3 Nut
1
2
3
125
Notes
Encoders
127
Encoders – 2 Channel Page
Encoders – 3 Channel Page
Encoders – Absolute Page
NEW
IE2-1024 magnetic 470 – 472
IEH2-4096 magnetic 473 – 475
PE22-120 optical 476 – 477
HEDS 5500 optical 478 – 479
HXM3-64 magnetic 480 – 482
HEM3-256-W magnetic 483 – 485
IEM3-1024 magnetic 486 – 488
IE3-1024 magnetic 489 – 493
IE3-1024L magnetic, Line Driver 494 – 497
IEF3-4096 magnetic 498 – 500
IEF3-4096L magnetic, Line Driver 501 – 503
IEH3-4096 magnetic 504 – 506
IEH3-4096L magnetic, Line Driver 507 – 509
IERS3-500 optical 510 – 512
IERS3-500L optical, Line Driver 513 – 515
IER3-10000 optical 516 – 519
IER3-10000L optical, Line Driver 520 – 523
HEDL 5540 optical, Line Driver 524 – 525
AESM-4096 magnetic 526 – 528
AES-4096 magnetic 529 – 531
AES-4096L magnetic, Line Driver 532 – 534
Encoders
Technical Information
General information
FAULHABER Motors are available with a variety of sensors and encoders for providing solutions to a wide range of drive applications – from speed control to high-precision positioning.
Sensors and encoders
FAULHABER Motors are offered in combination with sen-sors and encoders. An encoder is a sensor for angle meas-urement that is usually used for speed or position control.
The term sensor refers to digital or analog Hall sensor which, in the FAULHABER Brushless DC-Motors, are usually mounted directly on the motor circuit board. Digital Hall sensors are used primarily for the commutation of the Brushless DC-Motors and for simple speed control. Almost all FAULHABER Brushless DC-Motors are equipped stand-ard with three integrated digital Hall sensors.
S1
In addition, analog Hall sensors are generally available as an option.
180° 240° 300° 360°
HallA
Absolute mechanical rotational angle Hall signals HallA – HallC
Due to the higher resolution, the analog Hall sensors can also be used for precise speed or position control, making them an especially economical, lightweight and compact alternative to encoders. The option for analog Hall sensors can be found directly in the data sheets of the motors
under “Controller combinations”. If this option is selected, no encoder is needed. The space and cost advantages make analog Hall sensors the preferred solution for most positioning applications with Brushless DC-Motors. When selecting this option, it is recommended that the sensors be operated with FAULHABER Controllers, which are perfectly designed for the analog Hall signals.
Functionality
Measurement principle
The FAULHABER Sensors and Encoders are based on magnetic or optical measurement principles.
Magnetic encoders are especially insensitive to dust, humidity and thermal and mechanical shock. In magnetic encoders, sensors are used that determine the changes of the magnetic fi eld. The magnetic fi eld is changed by the movement of a magnetic object. This can be the magnet of the motor or an additional sensor magnet with a defi ned measuring element that is secured to the shaft of the motor. With encoders, an additional sensor magnet is usually necessary.
In the case of integrated digital or analog Hall sensors, the movement of the rotor magnet of the motor can be meas-ured directly. With the integrated Hall sensors, an addi-tional sensor magnet is therefore normally not necessary.
Optical encoders are characterised by a very high position accuracy and repeatability and a very high signal quality due to the precise measuring element. Furthermore, they are insensitive to magnetic interference. In optical encod-ers, a code disc with a measuring element is used that is attached to the shaft of the motor. A distinction is made between refl ective and transmissive optical encoders. With refl ective encoders, the light from an LED is refl ected back to the code disc by a refl ective surface and collected by photodetectors. Refl ective optical encoders are especially compact since the LED, the photodetectors and the elec-tronics can be mounted on the same circuit board or even on the same chip. FAULHABER therefore primarily uses refl ective optical encoders. With transmissive encoders, the light from the LED passes through slits in the code disc and is collected by photodetectors on the other side of the code disc.
Encoders
Technical Information
Moving Element
Depending on the measurement principle and dimen-sional constraints different moving elements are applied in different types of FAULHABER Encoders. The moving element has a signifi cant impact on the accuracy and reso-lution of the encoder. In general, the higher the physical (native) resolution of the moving element, the higher the resolution and accuracy of the encoder as a whole.
In magnetic encoders, simple, two-pole sensor magnets and magnetic rings are used. The magnetic rings have several signal periods per revolution through the use of a special tooth structure or targeted magnetisation. The number of signal periods corresponds to the physical reso-lution of the magnetic rings.
Two-pole sensor magnet with one signal period
Multi-pole magnetic ring with multiple signal periods
Magnetic ring with tooth structure
In optical encoders, moving elements in the form of code discs are used. With refl ective encoders, these consist of a series of surfaces that alternately refl ect or absorb light.
With transmissive encoders, the code discs consist of a series of bars and slits. The number of refl ective surfaces or slits corresponds to the physical resolution. In general, optical encoders can have a signifi cantly higher native resolution than magnetic encoders.
Code disc for refl ective encoders with high number of signal periods
Code disc for transmissive encoders with high number of signal periods
Signal processing and interpolation
In addition to the sensors for signal acquisition, the FAULHABER Encoders also include electronic components for signal processing. These process the signals from the sensors and generate the standardised output signals of the encoders. In many cases, the signals are also interpo-lated, i.e., multiple signal periods are generated by inter-polating a single physically measured signal period. The physical resolution of the measuring element can thereby be increased many times over.