Motion Control – Linear – High Torque Rotary Voice Coil Actuators!

Linear Motion Control - H2W High Torque Voice Coil Actuators

 

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Santa Clarita, CA —– Linear Motion Control – H2W Technologies has developed several high torque rotary voice coil actuators, otherwise known as a limited angle torque motors or LATs. The model TWR-015-346-2RC was designed to allow for a low moving mass (68 grams per coil) and inertia, as well as dual independent coils to allow for two independent motion profiles or couple the coils together to double the torque output. This rotary voice coil actuator can generate a continuous torque of 185 in-oz [1.29 N-m] and a peak torque of 555 in-oz [3.88 N-m] at a duty cycle of 10% (i.e. 1 second on, and 9 seconds off) in each coil on a 4 inch [102 mm] rotation arm. By coupling the coils together, the continuous torque doubles to 370 in-oz [2.58 N-m] with a peak torque of 1110 in-oz [7.75 N-m] at a 10% duty cycle.

The TWR-015-346-2RC has a total angular displacement of 15 degrees [0.26 radians] and a motor constant of 34.4 in-oz/sqrt(watt) [0.24 N-m/sqrt(watt)] per coil or when coupled together the motor constant is 48.5 in-oz/sqrt(watt) [0.34 N-m/sqrt(watt)]. The voice coil motor requires 1.33 amps of continuous current per coil and 4.0 amps of peak current per coil to generate the specified forces. The actuator fits in and envelope of 4.37 in [111.1 mm] x 2.99 in [75.9 mm] x 1.64 in [41.5 mm].

The moving coil design ensures a hysteresis free movement as the coil is wet wound and self-supported, and the non-commutated coil allows for ripple-free motion and no cogging. The voice coil actuator has been designed with mounting provisions in the magnet and coil assemblies. This allows for the integration of a bearing system to maintain the clearances between the coil and permanent magnetic field assemblies. The rotary voice coil actuator is ideal for applications requiring high torque and high-speed applications. Examples of such applications are driving a gimbal axis in scanning applications as well as providing stabilizing torques for image stabilization. More examples of H2W’s Rotary Voice Coils are available on our website: https://www.h2wtech.com/category/rotary-voicecoil-actuators

Technology

Simply stated, a current carrying conductor placed in a magnetic field will have a force (or torque) exerted upon it. This force is proportional to the direction and magnitude of the current and the flux density field. Since the permanent magnet flux density field is fixed, the direction of the rotation depends on the polarity of input current and the amount of torque that is produced is directly proportional to the magnitude of the input current.

Linear Motion Control - H2W High Torque Voice Coil Actuators - Drawing

 

 

 

 

 

 

 

 

 

 

A DC linear servo amplifier is required to provide power to the torquer.

Rotary voice coil actuators are supplied unhoused without bearings.

Coupling the rotary voice coil actuator to your bearing system and a rotary encoder or other feedback device yields a system that is capable of intricate angular position, velocity, and acceleration control.

Low moving inertia of the moving coil assembly allows for high angular acceleration of the payload.

Advantages:

  • No Torque Ripple
  • High Angular Acceleration
  • No Commutation
  • Zero Cogging
  • Brushless
  • Low Profile

Applications:

  • Aerospace
  • Semiconductor
  • Medical
  • Military

Rotary Voice Coil Motor – is an arc segmented multipole permanent magnet stator with a low inertia copper magnet wire rotor. Angular excursions are typically less than 90º. This torquer is supplied with out a shaft or bearing.

TWR Series Limited Angle Torque Motor

The TWR Series is comprised of a stationary, arc segmented, multipole permanent magnet stator assembly with a low inertia wound wire rotor.

Rotor: The rotor is made up of a single coil of bondable copper magnet wire. The coil is wound and preformed into the desired shape. It is held together with the bonding agents in the wire. It can be encapsulated with aluminum or plastic brackets in order to provide a means for mounting the rotor to the bearing system and payload. The maximum angular excursion is less than 90º.

Stator: The stationary stator assembly consists of multipole permanent magnets that are bonded to steel plates. The 2 opposing steel plates are spaced apart to provide a gap using end plates. The coil rotor assembly moves angularly within this gap. There is no magnetic attractive force between the stator and the rotor.

The TWR Series Torquers are available in 2 configurations.

The low profile (Type L) configuration has a smaller overall height which allows it to fit in a more compact space, but has less angular rotation for a given stator arc segment.

The second configuration (Type S) has a larger overall height but has typically twice the angular rotation per given stator arc segment when compared to the Type L torquer.

  • No Torque Ripple
  • High Angular Acceleration
  • No Commutation
  • Brushless
  • Low Profile

For Product Descriptions of High Torque Voice Coil Actuators CLICK HERE

About H2W Technologies, Inc.

H2W Technologies, Inc. is dedicated to the design and manufacture of linear and rotary motion products that are used in the motion control industry. The complete line of linear electric motors includes: Single and dual axis linear steppers, DC brush and brushless linear motors, voice coil actuators, and AC induction motors. Also offered is a complete line of ball screw, lead screw and belt driven positioning stages.

Other motion control products include: Limited angle torque motors for compact, limited angular excursion rotary servo applications, 3 phase brushless rotary servo motors with matching digital servo amplifiers and permanent magnet linear brakes for fail-safe, zero power braking for baggage handling and people moving applications as well as amusement park rides.

With over 75 years combined experience in the linear and rotary motion field, the H2W Technologies team of engineers offers the optimal solution to the most demanding motion control, requirements.

For additional information contact Mark Wilson at H2W Technologies, 26380 Ferry Ct, Santa Clarita, CA 91350; Tel: 888-702-0540, Fax: 661-251-2067, E-Mail: info@h2wtech.com or visit the website at http://www.h2wtech.com

 

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Motion Control – Custom Linear Mechanisms

Motion Control – Custom Linear  Mechanisms from Steinmeyer …

Motion Control Mechanisms – Welcome to Where Precision Is.  You Can Turn to Steinmeyer for Design and Assembly of Custom Linear Mechanisms for your Precision Positioning Systems
Motion Control Company
Modern mechatronic systems consist of numerous precision components that must be assembled in complex configurations. Here, every detail counts.
Steinmeyer Mechatronik, a division of August Steinmeyer GmbH,
offers design and assembly services for a variety of demanding applications.
We have deep experience in medical devices, laboratory instrumentation, optical inspection & semiconductor positioning. Our engineers can implement your finished design or optimize your concept.

For Example …Motion Control Linear Stage

Demanding series production for a medical instrument

The task was to develop a motion unit for a computer tomography scanner which moves tungsten collimators during X-ray source rotation so that the X-ray beam can be adjusted to the minimum radiation dose required. The assembly itself is continuously moved in a circular path around the patient during use. A special challenge was the high acceleration caused by the rotation on a large diameter transverse to the direction of movement. This additional load requires a particularly stable construction with minimal potential for error.

Highest stability and reliability

Since this is used in a durable medical device, the requirements for functional safety and reliability are very high. The positioning system has been tested for three million application cycles and has proven this claim with statistical certainty in an endurance test.

CLICK HERE to see this solution and others from Steinmeyer Mechatronik

Steinmeyer has decades of experience in precision assembly. All of our systems, whether single or multi-axis, are manufactured carefully. Our high standards, monitored continuously through vigorous quality systems, are evident in every assembly we produce. We pay attention to every detail.
Trust Steinmeyer With Linear Mechanism Solutions:
  • We can assemble custom linear mechanisms of all sizes – from miniature actuators using 3 mm linear rails, to 3 m long lifting mechanisms.
  • As an added value, our engineers will offer innovative ideas for optimizing your design.
  • We can quote a completely assembled module, including sourcing of key components!
  • We offer our customers the advantage of a close working relationship, enabling us to provide you with the best possible solution to meet your needs.

Contact Person for Custom Linear Modules

Bruce Gretz

Phone: 781-273-6220

Bruce Gretz   bruce.gretz@steinmeyer.com

About Steinmeyer

In the realm of linear motion control, Steinmeyer is synonymous with precision, innovation, and exacting standards of quality. We are the world’s longest continuously-operating manufacturer of commercial ball screws, our main product line. As an added value, we offer customized linear modules from our highly innovative and experienced Mechatronik division. Designed and manufactured in Germany, our products are used globally in precision positioning for medical devices, lab instruments, and other mechatronic applications. Steinmeyer engineers will work closely with you to customize our offering to deliver a solution that meets your technical requirements and budget.

For further information on Steinmeyer our extensive product portfolio, call 1-781-273-6220 or e-mail Rosemary Belt at rosemary.belt@steinmeyer.com or visit the Steinmeyer FMD group at: www.steinmeyer.com

 

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Motion Control – BSMAE Series of XY Stages with Precision Ball Screws from Intellidrives!

Checkout the BSMAE Series of XY Stages with Precision Ball Screws from Intellidrives!

Intellidrives Motion Control Ball Screw XY -Systems

 

Motion Control Components - Intellidrives-Logo

 

Philadelphia, PA, — Motion Control Components and Systems – XY stages with precision ball screws – Intellidrives new Low profile motorized actuators with precision ball screw provide exceptional accuracy, repeatability and ultra-fine positioning resolution capability to 1 micron in a very compact, low profile unit. They are ideal for space-critical applications such as optical, laser applications and vacuum operation.

 

There are 2 models in the series to select from:

XY-BSMAE-F40S

Intellidrives Motion Control Ball Screw XY -Systems

XY Stroke

mm

100×100
200×200
300×300

Screw lead

mm

5, 10

Motor mounts size

Nema17 (Nema23)

Motor type

Stepper (standard)

Servo/encoder

Load

kg

5

Repeatability

micron

30

Stage weight

kg

6

Speed

mm/sec

50 – 100 (stepper)

100 – 200 (servo)

Open loop Micro-stepping resolution = screw_lead/200/microsteps_per_step

where: motor has 200 full steps/rev;

driver micro-stepping resolution 64, 128, 256 micro-steps/step

Closed loop servo resolution = screw_lead/encoder_cpr/4

where: encoder_cpr is number of encoder counts per revolution;

4 is post-quad processing in the motion controller

XY_BSMAE-F40X

Intellidrives Motion Control Ball Screw XY -Systems

XY Stroke

mm

100×100
200×200
300×300

Screw lead

mm

5, 10

Motor mounts size

Nema17 (Nema23)

Motor type

Stepper (standard)

Servo/encoder

Load

kg

5

Repeatability

micron

30

Stage weight

kg

6

Speed

mm/sec

50 – 100 (stepper)

100 – 200 (servo)

Open loop Micro-stepping resolution = screw_lead/200/microsteps_per_step

where: motor has 200 full steps/rev;

driver micro-stepping resolution 64, 128, 256 micro-steps/step

Closed loop servo resolution = screw_lead/encoder_cpr/4

where: encoder_cpr is number of encoder counts per revolution;

4 is post-quad processing in the motion controller

MULTI-AXES NETWORKING JUST GOT SIMPLER

Intellidrives Motion Control Ball Screw XY -Systems

No need to daisy chain multiple axes, just plug USB cables into USB hub and control unlimited number of axes with a GUI.

XY Stages driven by SMART “all-in-one” solution with motor, driver, controller and encoder in the single compact package.

INTELLIGENT ACTUATORS are member of the Compact Positioning Stages family of linear, rotary, XY and vertical lift stages.

Two or more stages can easily be mounted together in numerous combinations using adapter plates and brackets.

INTELLIGENT ACTUATORS can easily “talk over” USB 2.0 interfaces and come with powerful yet easy to use software packages for system start-up and integration, like communication drivers, linkable DLL libraries, National Instruments Labview drivers and VI examples, GUI and easy-to-use DXF conversion software.

 

FOR ADDITIONAL INFORMATION – CLICK HERE

 

About IntelLiDrives —

IntelLiDrives, Inc. manufactures linear actuators, XY tables and rotary tables for the industry, government, science and research institutions around the world. Our precision rotary actuators, XY stages and linear actuators are used in the applications in medical devices, life sciences, semiconductor and electronic assembly manufacturing, data storage, laser processing, military/aerospace, photonics, automotive and test assembly, research and development and other industries requiring high precision and throughput motion control solutions.

For further information on this new product or others in our extensive product portfolio, call 1-215-728-6804 or e-mail Intellidrives at sales@intellidrives.com or go Intellidrive – Contact Us at: www.intellidrives.com/contact-us

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“New Design” Pillow Blocks from LM76!

Engineering edge - new design pillow block

When our customer, a major European manufacturer of machinery for the paper industry, informed us they were having failures with linear bearings in their robotic paper slicing system, we listened. As a robotic arm swings around (360 degrees) it slices the paper to length. After cutting the paper to length, a linear table below indexes new paper forward for cutting. After making the desired cut, the blade then passes through sharpeners below – located in the indexing table – where the linear bearings are located. As the blade passes through the sharpeners, it deposits a fine metal dust on the shafts. As the bearings pass over the shafts, the metallic grit invades the bearing – eventually leading to bearing failure. Because there are 32 pillow – 50mm – pillow block bearing assemblies, change-out is no small matter. LM76 designed an End Cap/Beryllium Scraper Seal kit which is retained in both ends of the pillow block. We were able to cut downtime by 90%. The customer is extremely pleased they found an answer. But the answer was not found in any catalog, it had to be designed and manufactured. 

 

About LM76 and “The Engineering Edge”

Founded in 1976, LM76 has been a leading designer/manufacturer of linear bearings, slides and linear motion systems. LM76 is renowned for its industry leading Minuteman PTFE Composite linear bearings. LM76 is a leading supplier of precision linear shafting: RC60, 300 Series Stainless Steel, and ceramic-coated aluminum shafting. LM76 also offers several FDA/USDA compliant linear bearings and slides for the food processing, pharmaceutical, medical, and packaging industries.

When others think catalog …   … LM76 thinks solution!

For additional information contact Mike Quinn at: LM76, 140 Industrial Dr., E. Longmeadow, MA 01028; Telephone: 413-525-4166, Fax: 413-525-3735 or E-Mail: mquinn@lm76.com or visit the website at http://www.lm76.com

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Motion Control – Maxon’s New EPOS Programmable Smart Drive/Controller – “Positioning Made Easy” are Available from Electromate!

Motion Control EPOS Controllers

 

Motion Control - Electromate-Logo

 

Vaughan, Ontario, Canada — Motion Control Components — EPOS is a modular, digital positioning controller by maxon motor. It is suitable for controlling permanent magnet-activated motors with encoders in a range of 1 to 1050 W continuous output power. The wide range of operating modes, as well as various command interfaces, make it versatile for use in many different drive systems in the fields of automation technology and mechatronics

With the EPOS4 Compact 50/8 EtherCAT and EPOS4 Compact 50/15 EtherCAT, maxon launches the first compact devices compatible with the fast industrial Ethernet connection EtherCAT. The fully integrated, plug-and-play positioning controller in a compact design is perfectly suited for use in networks with cycle times up to 1 ms.

Powerhouse with excellent control characteristics

The functionality, operation, software, and accessories of the new controllers are derived directly from existing products in the EPOS4 range. The devices are suitable for use with both brushed DC and brushless EC motors (BLDC) and come with comprehensive feedback options such as Hall sensors, as well as incremental and SSI absolute encoders. State-of-the art concepts such as FOC, feed forward, and observer control allow optimal control in a wide variety of applications.

Comprehensive functional scope and easy operation

The existing digital and analog inputs and outputs are freely configurable and ideally matched to the numerous functions and operating modes of CiA-402 positioning controllers. Products are set up using the EPOS Studio graphical user interface (Version 3.4 and higher) for Windows PCs. In addition to the intuitive commissioning software, Windows DLL and Linux Shared Objects libraries are freely available to make integration into a wide variety of master systems as easy as possible.

Motion Control - Maxon EPOS Controllers
Electromate offers Maxon EPOS Controllers

About Electromate:

Electromate’s Core Purpose is to help Manufacturers build better machines using differentiated automation technology. They specialize in Robotic and Mechatronic Solutions for the Industrial Automation marketplace. Respected by customers as a premiere source for High Performance Automation and Motion Control Components & Systems, Electromate® specializes in AC & DC Servo and Stepper Motors & Drives, Motion & Automation Controllers, Positioning Systems & Actuators, Feedback Devices, Gearing Products and HMI’s & Operator Displays, all supported via extensive product selection, just-in-timedelivery, dedicated customer service and technical engineering support.

More on Electromate can be found at

Website: http://www.electromate.com

LinkedIn: https://www.linkedin.com/company-beta/209277/

Twitter: https://twitter.com/Electromate

Facebook: https://www.facebook.com/electromateindustrial/

Google+: https://plus.google.com/104057418684128701566

Blog: https://electromate.wordpress.com/

Electromate Best Blace to Work

For more information on the “Best Place to Work”CLICK HERE!

To view Electromate’s new corporate video CLICK HERE

For further information on this new product or others in our extensive product portfolio, call 1-877-SERVO99 (737-8699) or e-mail Warren Osak at sales@electromate.com or visit Electromate at: www.electromate.com

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Motion Control – For a Safer Workplace Use the Safety Laser Scanner From OMRON!

For a Safer Motion Control Workplace!

OMRON Motion Control Component - Safety Scanner

Motion Control Components - Omron Logo

 

Hoffman Estates, IL -Motion Control Automation and Safety -Motion Control Components and Systems – Small size, less weight and low-power consumption are extending operation time of battery powered systems like automated guided vehicles (AGVs). The OMRON Safety laser scanner OS32C covers all these requirements in collision avoidance, presence and intrusion detection applications. Maintenance is made simple since diagnosis is clear having LED displays.

OMRON Motion Control Component - Safety Scanner

 

Features:

  • Type 3 Safety Laser Scanner complies with IEC61496-1/-3
  • 70 sets of safety zone and warning zone combinations
  • Safety zone up to 4m and warning zone(s) up to 15m.
  • 8 Individual Sector indicators and various LED for clear status indication
  • Reference boundary function prevents unauthorized change of scanner position

 

OMRON Motion Control Component - Safety Scanner Data Sheet

OMRON Motion Control Component - Safety Scanner Brochure

 

To Down Load OMRON Safety Laser Scanner OS32C Brochure CLICK HERE

To Down Load OMRON Safety Laser Scanner OS32C Data Sheet CLICK HERE

For additional information on OMRON Safety laser scanner OS32C CLICK HERE

To subscribe to OMRON Newsletters CLICK HERE

To contact OMRON about this or other industrial products CLICK HERE

KEEP YOUR WORKPLACE SAFE! – GET A ‘GOTCHA-STICK” CLICK HERE

Motion Control Components - Omron Logo

Motion Control Components - Omron Logo


 

 

The Engineering Edge – Application – Trunnion Grinding Slide for Oil Field

motion control grinding slide

 

Motion Control – Application Story – We are shipping another slide today for the oil patch. When Weir Oil and Gas called with a slide application that required special engineering, LM76 was all ears – as it was right up our alley. This slide is a Trunnion Grinding Slide which has a 56HP motor running at 3500 RPM mounted to the Y Axis – with a 12″ grinding wheel attached. The X Axis (52″ Stroke) runs on 440C stainless linear ball bearings that have special beryllium copper scraper seal cartridges while the Y Axis (4″ Stroke) employs profile rail guides with double scraper seal kits. Our customer did not want protective bellows so we had to ensure grinding debris would not cause bearing or screw/nut failures. On both axis, we employed our proprietary “Polymatrix, Double Preloaded Nuts” as opposed to recirculating ball nuts. Why LM76? Good question…we were the only company that got back to them with a thoughtful solution.

About LM76 and “The Engineering Edge”

Founded in 1976, LM76 has been a leading designer/manufacturer of linear bearings, slides and linear motion systems. LM76 is renowned for its industry leading Minuteman PTFE Composite linear bearings. LM76 is a leading supplier of precision linear shafting: RC60, 300 Series Stainless Steel, and ceramic-coated aluminum shafting. LM76 also offers several FDA/USDA compliant linear bearings and slides for the food processing, pharmaceutical, medical, and packaging industries.

When others think catalog …   … LM76 thinks solution!

For additional information contact Mike Quinn at: LM76, 140 Industrial Dr., E. Longmeadow, MA 01028; Telephone: 413-525-4166, Fax: 413-525-3735 or E-Mail: mquinn@lm76.com or visit the website at http://www.lm76.com

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Motion Control – High Performance Ultra Compact Stepper Motor Positioning Stage From Equipment Solutions!

motion control miniature stage

 

Sunnyvale, CA, – — The motion control SMS12 Linear Stepper Motor stage is an ultra compact stage that provides up to 12 millimeters of linear motion. This stage offers near sub-micron resolution with the ability to accelerate a small load at 2G’s. A non-contact home sensor provides a reference position with repeatability of a couple microns. It was specifically developed for optical applications requiring both high precision and modest-speed positioning over a short to medium stroke. The SMS12 is well suited for optical focusing and other micropositioning applications such as scanning interferometry, surface structure analysis, disk drive testing, autofocus systems, confocal microscopy, bio-technology, semiconductor test equipment.

 

Specifications:

  • Translation 43µm/step
  • 0.67µm @ 64µstep/step
  • Maximum Travel 12mm
  • Maximum Acceleration 2G
  • Maximum Velocity 250mm/sec
  • Maximum Load Capacity 13kg
  • Maximum Moment Load 1.8kg
  • Positioning Accuracy ±2µm
  • Bidirectional Repeatability ±1µm
  • Homing Repeatability ±1µm
  • Motor Amps/Phase 0.3
  • Dimensions 39.1 x 39.1 x 31.75mm

The SMS12 can be ordered with an optional stepper motor controller that is nearly the same size a the SMS12 itself. Only raw power and a simple RS232/RS485 communications line is needed to completely control this high-resolution stage.

motion control - SMS-12 Stepper Motor Stage

Equipment Solutions, Inc. (ESI) is a provider of engineering and manufacturing services. ESI specializes in the design and production of automation and instrumentation products including motion control components and sub systems. ESI’s products range from galvanometer amplifiers with an integrated arbitrary waveform generator, to high-resolution displacement sensors, voice coil and stepper motor stages, amplifiers and controllers.

To view and/or down load the Data Sheet CLICK HERE

For additional information contact Jeff Knirck at Equipment Solutions, 1098 West Evelyn Ave. #102, Sunnyvale, CA 94086; Tel: 408-245-7161, Fax: 408-245-7160, E-Mail:info@equipsolutions.com or visit the Website at http://www.equipsolutions.com

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Motion Control – High Performance Servo Gearbox is ideal for Cyclic or Continuous High Speed Applications!

Motion Control - Electromate offers GAM's Planetary Gearbox

 

Motion Control - Electromate-Logo

Motion Control Components – The SPH inline planetary gearbox available from Electromate is GAM’s latest solution for today’s demanding motion control challenges! 

Vaughan, Ontario, Canada — Motion Control Components — It is available in six frame sizes with nominal torque ratings from 15 to up to 900Nm. The SPH features precision cut helical gears that are ground for smoothness, quiet operation, and high accuracies. The face width of the SPH gears are up to 70% longer than the gears in comparable gearboxes on the market, which means more tooth contact and greater overall torque density. To carry the higher torques, SPH gears are case hardened which imparts strength deeper into the gear compared to nitriding which hardens just the surface. With several output configurations available, machine integration is simplified.

Motion Control - Electromate offers GAM's Planetary Gearbox

SPH Series Benefits

  • Helical Gearing
  • Lower backlashes
  • Lower noise levels
  • Smoother torque transmission.

CLICK HERE for additional information on the GAM SPG Gearbox

About Electromate:

Electromate’s Core Purpose is to help Manufacturers build better machines using differentiated automation technology. They specialize in Robotic and Mechatronic Solutions for the Industrial Automation marketplace. Respected by customers as a premiere source for High Performance Automation and Motion Control Components & Systems, Electromate® specializes in AC & DC Servo and Stepper Motors & Drives, Motion & Automation Controllers, Positioning Systems & Actuators, Feedback Devices, Gearing Products and HMI’s & Operator Displays, all supported via extensive product selection, just-in-timedelivery, dedicated customer service and technical engineering support.

More on Electromate can be found at

Website: http://www.electromate.com

LinkedIn: https://www.linkedin.com/company-beta/209277/

Twitter: https://twitter.com/Electromate

Facebook: https://www.facebook.com/electromateindustrial/

Google+: https://plus.google.com/104057418684128701566

Blog: https://electromate.wordpress.com/

Electromate Best Blace to Work

For more information on the “Best Place to Work”CLICK HERE!

To view Electromate’s new corporate video CLICK HERE

 

For further information on this new product or others in our extensive product portfolio, call 1-877-SERVO99 (737-8699) or e-mail Warren Osak at sales@electromate.com or visit Electromate at: www.electromate.com

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Motion Control Tutorial – Slotted vs. Slotless Motor Technology

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When first introduced, brushless DC motors, despite their many advantages, were cast as a costly alternative to brush-commutated motors and were typically only specified for low-power applications where long life was the primary desired requirement. Without the mechanical brush-commutator mechanism that would wear and eventually result in motor failure, brushless motors could be relied upon to deliver performance over time. As for other advantages, conventional wisdom held that brushless motors provide high speed and fast acceleration, generate less audible noise and electromagnetic interference, and require low maintenance. Brush-commutated motors, on the other hand, would afford smooth operation and greater economy. In the past decade, though, brushless motors have gained broader appeal and greater acceptance in industry for a wider range of applications previously dominated by brush-commutated products, due in part to dramatic reductions in the cost and size of electronic components and advances in motor design and manufacturing.

At the same time, manufacturers have further sought to challenge conventional wisdom by improving brushless motor design in an effort to combine the traditional advantages of brush-commutated and brushless types. A noteworthy example of how far these innovations have progressed involves the slotless (instead of slotted) construction of the brushless motor’s stationary member, or stator.

The slotless stator design originated with the goal to deliver smooth running performance and eliminate cogging, which is an unwanted characteristic especially in slower-running applications (less than 500 rpm). The absence of cogging is, in fact, the most-often cited reason for selecting a slotless brushless motor.

Slotted Motor Construction

Most brushless motors (slotted or slotless) use electronic commutation, usually Hall-effect sensors and magnets, in place of brushes. The motor’s rotor consists of a steel shaft with permanent magnets or a magnetic ring fixed around the circumference of the shaft. The magnets are responsible for producing torque. As the flux density of the magnet material increases, the amount of torque available from the rotor assembly increases.

In traditional slotted brushless motors, the stator features a group of slotted steel laminations (0.004 in. to 0.025 in. thick), which are fused to form a solid uniform stack and create a series of teeth. Wound copper coils, which produce electromagnetic fields, are then inserted into each of the slots. Together, the laminated stack and wound copper coil form the stator assembly. The return path completing the magnetic circuit consists of the laminated material outboard of the copper windings in the stator and the motor housing.

These brushless slotted motors are especially powerful, because the teeth around which the copper wire is wound place the iron closer to the magnets, so the magnetic circuit is completed more efficiently. As the air gap between iron and magnets is reduced, the torque available for the motor is increased.

However, slotted stators are known to cause cogging, which is attributed to the teeth in their construction. Cogging occurs when the permanent magnets on the rotor seek a preferred alignment with the slots of the stator. Winding copper wires through the slots tends to increase this effect. As magnets pass by the teeth, they have a greater attraction to the iron at the ends of the teeth than to the air gaps between them. This uneven magnetic pull causes the cogging, which ultimately contributes to torque ripple, efficiency loss, motor vibration, and noise, as well as preventing smooth motor operation at slow speeds. A slotless stator offered a solution to the problems experienced with cogging in slotted brushless DC motors.

Advantage of the BLDC Slotted Motor Technology

The main advantages of the slotted technology are:

  • ease of winding customization
  • increased heat dissipation
  • ability to withstand high peak torque
  • high power density

Slotted Motor Applications

The Slotted Motor is ideal for applications such as:

  • Medical Hand Tools
  • Hand held shaver system for arthroscopic surgeries
  • High speed surgical drills for ENT surgeries

Slotless Motor Construction

Instead of winding copper wires through slots in a laminated steel stack as in conventional slotted brushless motors, slotless motor wires are wound into a cylindrical shape and are encapsulated in a hightemperature epoxy resin to maintain their orientation with respect to the stator laminations and housing assembly. This configuration, which replaces the stator teeth, eliminates cogging altogether and results in desired quiet operation and smooth performance.

The slotless design also reduces damping losses related to eddy currents. These currents are weaker in a slotless motor, because the distance between the laminated iron and magnets is greater than in a slotted motor.

Slotless motors are typically designed with sinusoidal torque output that produces negligible distortion, rather then a trapezoidal voltage output. The sinusoidal output reduces torque ripple, especially when used with a sinusoidal driver. Because the slotless design has no stator teeth to interact with the permanent magnets, the motor does not generate detent torque. In addition, low magnetic saturation allows the motor to operate at several times its rated power for short intervals without perceptible torque roll-off at higher power levels.

Compared with slotted motors, slotless construction also can significantly reduce inductance to improve current bandwidth. The teeth in a slotted motor naturally cause more inductance: the coils of copper wire around the teeth interact with the iron in a slotted motor, and this interaction tends to send the current back on itself, resulting in more damping (or dragging) and impacting negatively on slotted motor response and acceleration.

In terms of delivering power, conventional slotted motors used to enjoy the advantage over slotless types, due (as noted) to the proximity of iron and magnets and the reduced air gap.

However, this advantage has virtually evaporated, in large part due to the utilization of high-energy, rare-earch magnets (such as samarium cobalt and neodymium iron boron). By incorporating these magnets, manufacturers of slotless brushless motors have been able to routinely compensate for the greater air-gap distance. These more powerful magnets effectively enable the same (or better) torque performance for slotless products compared with slotted. Eliminating the teeth and using stronger magnets both serve to maximize the strength of the electromagnetic field for optimum power output. Rare-earth magnets, along with the fact that fewer coils, or “turns,” of the wire are required in slotless motors, also help contribute to low electrical resistance, low winding inductance, low static friction, and high thermal efficiency in slotless motor types.

One more important difference between slotless and slotted designs is the rotor diameter. Slotless motors have a larger rotor diameter than slotted construction for the same outside motor diameter and will generate a higher inertia, as well as accommodating more magnet material for greater torque. For applications with high-inertia loads, the slotless product is more likely to be specified.

Slotless Motor Applications

In general, brushless motors are usually selected over brushcommutated motors for their extended motor life. (While motor life is application-specific, 10,000 hours are usually specified.) Other reasons for specifying brushless motors include a wide speed range, higher continuous torque capability, faster acceleration, and low maintenance.

In particular, slotless versions of brushless DC motors will suit those applications that require precise positioning and smooth operation. Typical niches for these motors include computer peripherals, mass storage systems, test and measurement equipment, and medical and clean-room equipment.

As examples, designers of medical equipment can utilize slotless motors for precise control in machines that meter and pump fluids into delicate areas, such as eyes. In medical imaging equipment, slotless brushless DC motors decrease banding by providing the smoother operation at low speeds. Airplane controls supply smoother feedback to pilots. And, by eliminating cogging and resulting vibration, these motors can reduce ergonomic problems associated with hand-held production tools. Other appropriate applications include scanners, robots for library data storage, laser beam reflector rotation and radar antenna rotation equipment, among many others./span)

Customization Options

Slotless brushless DC motors, as with most motors today, feature a modular design so they can be customized to meet specific performance requirements. As examples, planetary or spur gearheads can be integrated on motors for an application’s specific torque and cost requirements. Planetary gearheads offer a higher-torque alternative. Slotless motors can further be customized with optical encoders, which provide accurate position, velocity, and direction feedback that greatly enhances motor control and allows the motors to be utilized in a wider range of applications. As a low-cost alternative to optical encoders, rotor position indicators (ie. Hall Sensors) can be specified.

When using optical encoders, differential line drivers can be utilized to eliminate the effects of electrically noisy environments. Differential line drivers are designed to ensure uncorrupted position feedback from the encoder to the control circuit.

Motor Selection Guided by Application

Despite the overall design and performance comparisons reviewed here for slotless and slotted brushless DC motor types, one should remain cautious in drawing any conclusion that one type is the ultimate choice over the other. There are simply too many variables that must be evaluated, ranging from rotor size and windings to housing and special components. A given application and its requirements should (and will) be the guiding factors in selecting a particular motor type and the customized components to be incorporated.

Some encouraging news in those applications that would clearly benefit from a slotless brushless motor is that costs are coming down to be more in line with those for slotted motors. This is because of new streamlined manufacturing techniques and an increasingly available supply of powerful magnets, which are both beginning to have a positive impact on end-product costs.

Regardless of any cost differential, however, for many applications, slotless brushless DC motors will be the preferred choice to resolve specific requirement issues. While advances in electronics are beginning to be applied that promise to reduce normal cogging in slotted products as a step toward making these motors more smooth running and quiet, the industry is not there yet: slotless motors remain the best alternative where cogging and life are defining performance issues

This Tutorial and other Motion Control Tutorials are available through www.Servo2Go.com

For further information on this new product or others in our extensive product portfolio, call 1- 877-378-0240 or e-mail Warren Osak at warren@servo2go.comor visit Servo2Go.com at: www.Servo2Go.com

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