When operating a stepper driven system, an AC motor, or a Servo motor, an encoder can be added to monitor for speed and position control. More specifically, a linear encoder can be used to provide feedback for motors that move in linear motions. By utilizing a linear encoder, errors that occur frequently like backlash, system lags, and abbe errors can be reduced. At Leading Edge Industrial, we understand the importance of precision when completing projects—which is why we have provided information about the function of a linear encoder, which is a simple and efficient tool to utilize.
What is the Function of a Linear Encoder?
The role of a linear encoder is to monitor linear movements within a motor and then provide feedback from those movements in the form of electrical signals. A linear encoder provides information about position, which can be used to determine if a motor is performing as accurately as it could. Linear encoders also provide valuable information concerning velocity, direction, and position to operators.
Incremental Linear Encoder Function
In order to provide different benefits and serve different machinery, a linear encoder can be classified as either incremental or absolute.
An incremental linear encoder is used for counting pulses or for monitoring processes like speed, position, and direction. Incremental encoders are also a more cost-efficient option when compared to absolute encoders.
So how does an incremental encoder function?
Linear encoders operate by creating two output signals (one “A” and “B” signal), but these encoders may only require the use of readings of one pulse if the position is only needed to be known. These output signals contain a 90º offset, which is necessary for the encoder’s rotation. These encoders also have phasing between the two outputs, which is called quadrature. The resolution of an incremental encoder is determined by the number of electrical signals per distance, which can be measured in inches or millimeters.
When turned on, the encoder starts at zero with no information. Since the encoder solely reads pulses, it is only able to display how far it has moved since its last use, which can lead to confusion about current location if the encoder was not measured carefully from a known location.
Absolute Encoder Function
While incremental encoders can only give us a general idea of location, absolute encoders can tell us the precise location of a motor by using distance-coded reference marks. So why is this ability so beneficial?
By using distance-coded reference marks, an absolute encoder has the capacity to save true position location, even if the power is turned off—meaning you will never lose your place location. Each reference mark has a unique spacing from the next. The encoder reads the distinctive position and distance between two reference marks to determine both the distance and direction traveled. Program flexibility is also offered with these encoders because a homing system is not necessary. By not having a homing system, a point-to-point reference can be established with no need to start from a home position.
When Should Linear Encoders Be Used?
Material Handling:
Devices like conveyor belts, forklift machines, shrink wrappers, case packers, and many more use linear encoders. By utilizing an encoder, a machine can operate both quickly and accurately.
Tool/Die Industry:
Linear encoders are perfect for milling and boring mill applications, as well as for lathe and grinding machines. For increased precision and position control, linear encoders are often attached to the axes of a lathe. Linear encoders also aid lathe machines with tracking the actual path of the cutting tool—despite factors like wear, slippage, or backlash. Usually, linear encoders are just add-on components, but they have the potential to save money by increasing the accuracy of operations.
Mobile Machinery:
Machines like harvesters, mobile lifts, and extendable booms all use linear encoders in order to function properly. Encoders help people track shaft movement, so they are used when completing a task that needs increased accuracy and precision.
The Textile Industry:
Used in printing, knitting equipment, gluing machines, and seaming systems, encoders are valued for their ability to correct position as well as provide a quiet operation.
Airline Industry:
Often times, linear encoders are used in conjunction with airline companies in machines like baggage conveyor belts, antenna positioning, and other aircraft machinery. Built with a durable nature, linear encoders are perfect for handling situations like shock or extreme fluctuation in temperature.
Listed above are just a few applications of how linear encoders can be utilized throughout diverse machinery fields. Encoders are also commonly used in the food and beverage industry, and the printing and timber industries.
By pairing a linear encoder with your machinery, you can achieve more accuracy and speed and position control when operating different devices. Affordable and easy to use, encoders have been advancing the way positioning is handled across the machining industry. For more questions concerning linear encoders, visit Leading Edge Industrial—we’re happy to help
Sources:
https://en.wikipedia.org/wiki/Linear_encoder
https://en.wikipedia.org/wiki/File:Optical_Encoder_trio.png