Application / Advisor: Motors
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Micro Motors 2ph Stepper Motors
Specialty/ Slim Line Motors 3ph Stepper Motors
5ph Stepper Motors
 
Servo vs Stepper Motors & much more... Sample applications & much more...
 
Application / Advisor: Motors
Check to see which best fit your needs. If you have any questions, please call for assistance at 1-800-790-7837 or e-mail sales@netmotion.com
Servo -vs.- Stepper - How are they different?

Stepper motors are permanent magnetic motors that 'step' one increment each time the computer gives its control electronics one pulse. They don't require position feed back if run within their limits. When stopped they inherently hold their position.

Servo motors are standard DC or brushless motors with an encoder feedback loop. The computer reads the position of the motor and controls the power applied to the motor.

Stepper motors generally are just as accurate as servos and are simpler and more reliable and maintenance free in harsh dusty applications. The servomotor's encoder is susceptible to dirt and vibration causing problems.

Servo's are faster moving point to point and are better at accelerating very heavy machinery, but their higher maintenance should be a factor in deciding which to go with. Our stepper motor system can be just as fast or faster than many servo systems because of the control's software's algorithms.

Many companies that sell servo controls try to run steppers down. They don't know how good a properly made stepper motor system can be! Our stepper systems never loose steps and can run for days with perfect repeatability . A servo system with dust on the encoder will loose steps.

Motion Characteristics Servo Motors Stepper Motors
High Torque, Low Speed Can be considered if cost/ complexity is not an issue. Continuous duty applications requiring high torque and low speed.
High Torque and high speed (>2000 rpm) Continuous duty applications requiring high torque and high speed. A DC servomotor can deliver greater continuous shaft power at high speeds compared to steppers. High speed up to 12000 rpm is possible. AC servo motors can handle higher current surges compared to DC servos. You can get lot stronger AC servo compared to either DC servo or DC stepper. If speeds are less than 2000 rpm stepper may be economical. Stepper becomes bulky at high torque.
Short, Rapid Repetitive Moves Use servo if you need high dynamic requirements. Stepper will offer more economic solution when requirements are more modest.
Positioning Applications Servo can handle effectively when load is mostly inertia instead of friction. The ability to overdrive servo motor in intermittent duty allows a smaller motor to be used. If positioning is critical in micron level use servo. Use stepper motor if torque is lower than 500 oz-in, less 2000 rpm, low to medium acceleration rates.
Applications in Hazardous Environments Use brushless servo motor. Use step motor.
Low Speed, High Smoothness Use DC servo. Use microstepping.
Control Method Closed loop. Preferred to be used in open loop applications.
 
Stepper motor selection procedure
1. Determining the drive mechanism component First determine certain features of the design, such as mechanism, rough dimensions, distance moved, and positioning period
Determining the mechanism and required specifications
2. Calculate the required resolution From the required resolution, determine whether a motor only is to be used whether a geared motor is to be used.
Find the step angle resolution for the motor
3. Determine the operating pattern Find the acceleration (deceleration) period and operating pulse speed in order to calculate the acceleration torque.
Determine the operating pattern that fulfills the required specifications
4. Calculate the required torque Calculate the load torque and acceleration torque and the required torque demanded by the motor.
Calculate load torque
Calculate acceleration torque
Calculate required torque
5. Select motor Select a motor whose speed -torque characteristics satisfy the requirement.
Make a provisional selection of a motor based on required torque
Determine the motor to be used from the speed-torque characteristics
6. Check the selected motor Check the acceleration/ deceleration rate and inertia ratio in order to determine the suitability of the selection.
Confirm the acceleration/ deceleration rate and inertia ratio
 
Where are stepper motor being used?
Stepper motors can be found almost anywhere. Most of us use them everyday without even realizing it. For instance, steppers power "analog" wristwatches (which are actually digital), disc drives, printers, robots, cash points, machine tools, CD players, profile cutters, plotters and much much more. Unlike other electric motors they do not simply rotate smoothly when switched on. Every revolution is divided into a number of steps (typically 200) and the motor must be sent a separate signal for each step. It can only take one step at a time and each step is the same size, thus step motors may be considered a digital device. See below for more applications:
 
Sample stepper motor applications
 
 
Sample servo motor applications for Semiconductor related industries
Forming Machines Servo-Press Machines
 
Sample servo motor applications for Biotechnology/ Pharmaceutical related industries
Macroarray Staining Machines Macroarray Staining Machines
 
AC Servo Motor Application
Labeling Machine
Application Description:
Bottles on a conveyor run through a labeling mechanism that applies a label to the bottle. The spacing of the bottles on the conveyor can slow down, speed up, or stop at any time.
Machine Requirements:
  • Synchronization to conveyor label to bottle in motion
  • Allow for variable conveyor speed
  • Allow for inconsistent distance between bottles
  • Pull label web through dispenser
Motion Control Requirement:
  • Synchronization to conveyor axis
  • Electronic gearbox function
  • Registration control
  • Open-loop stepper if possible
  • High torque to overcome high friction
  • High resolution
Application Solution:
A motion controller that can accept input from an encoder mounted to the conveyor and reference all of the speeds and distances of the label roll to the encoder is required for this application. A servo system is also required to provide the torque and speed to overcome the friction of the dispensing head and the inertia of the large roll of labels. A photosensor connected to a programmable input on the controller monitors the bottles' positions on the conveyor. The controller commands the label motor to accelerate to line speed by the time the first edge of the label contacts the bottle. The label motor moves at line speed until the complete label is applied, and then decelerates to a stop and waits for the next bottle.
Application Type: Following         Motion: Linear
 
AC Servo Motor Application
Drive Train (Complete Synchronization) In distributed, multi-axis applications that require electronic gearing and cam profiles, synchronous, high speed updates of position commands are essential. NetMotion offers systems which will ensure complete synchronization between the controllers and all salves at a high communication rate. Our products offers a set of drivetrain objects that can be used to electronically link axes together in geared or mapped relationships.
 
Sample linear and rotary automation module
NetMotion provides solutions for your motion control designs. We carry linear and rotary automation modules that can be found in all phases of manufacturing, assembly, and handling processes. We offer a wide range of solutions from compact linear modules to rotary modules with the capability of withstanding very high axial and radial loads. Call us at 1-800-790-7837 or e-mail at sales@netmotion.com
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For further information, please contact NetMotion, Inc. at 1.800.790.7837 or 510.578.2811 or e-mail sales@netmotion.com
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