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Encoder Applications

Examples of uses for an industrial rotary encoder

Encoders may be used in a wide variety of applications. They can be used as feedback devices for motor speed control, length measurement, position and input for rate and speed indication and control. A few of the specific areas where encoders are used are listed below followed by some practical examples.

Following are a few practical examples of common encoder installations within these and other areas.

Applications Examples

Motor Speed / RPM Readout is the most common way that encoders are used. In this type of application, the encoder is mounted directly to the end of a motor via a shaft. The critical parameter of measurement is motor speed whereby the encoder provides feedback to a drive, so that the drive can verify that the speed and direction is correct. This team effort between the drive and the encoder ensures that whatever the motor is driving runs safely and smoothly and does not run out of control or erratically in applications where precise speed is a requirement. As the second diagram shows speed can also be monitored and controlled by a simple measuring wheel running on the material. In this case the motor would be coupled to a drive roller. Hollow shaft encoders mounted over the motor shaft are frequently used thereby eliminating the need for a flexible coupling and saving space.

Web Speed / Tension Control is an application in which an encoder is mounted to a motor as well as a tension roller. Any unevenness in the rotating speed of the tension roller is fed to a controller which sends a signal to the drive motor to adjust in order to maintain an even tension proportion between the web roller and drive motor. Maintaining optimal web tensioning is critical in assembly and conveyor applications or in roll tensioning applications designed to prevent tearing, backlash or other potential injury to machine operators

Linear Measurement / Cut-to-Length is a form of linear measurement whereby an encoder is mounted on a lead screw or measuring wheel to prevent a user from having to physically measure (using a tape measure or inaccurate hand mark or eye estimate) a length of material before it is cut. Since an encoder delivers a fix number of pulses in a revolution, a device can be scaled to increment at a designated length per pulse. This device may be a preset counter or PLC that in turn has a relay output that can be set to operate when the desired length is reached to ensure a precise and accurate cut every time.

Multi- axis control can be achieved using incremental or absolute encoders. They need to be high resolution accurate devices and are used in a variety of automated applications in manufacturing and research
Radar antenna, robotic arms or satellite dish rotation are good examples of this type of application.

Position Measurement / Backstop Gauging this position measurement application is similar to a cut to length application whereby the encoder is used to make sure that the unit, typically a machine tool, does not exceed a preset position or direction of travel. Very often, this is combined with a determination of the speed of travel of the table, tool head, or similar component to ensure that the machine does not over travel. Though limit switches can be used in backstop applications, encoders are more shock resistant and tend to last longer.

Position Measurement / Conveying is another common industry application where encoders are widely used to monitor and control conveyor speed and position. Similar to a motor feedback application, encoders are attached to a motor, to intermediate axle shafts, or to both. The critical parameters of measurement are motor speed and incremental movement. In this case the encoder can control both the conveyor speed and position

Position Measurement / Spooling is another application where encoders are advantageous. The encoder is mounted to the shaft of a spool, and the connected controller keeps track of the length and speed of the take up material being spooled based on feedback from the encoder.


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