Encoder Disks

Encoder Disks

An encoder disk is a key part of an encoder or sensing device used to enable control systems to identify motion, position, speed, direction, or count. Encoder disks essentially convert motion into electrical signals. They may be integrated with printed circuit boards, optical components, or magnetic devices; therefore, each disk must be precisely engineered, which is achieved with photo chemical etching.


Encoders come in different forms. Here are the most common ones you’ll find:

Rotary Encoder

Senses the angular position or motion of a shaft or axle. The information is converted to analog or digital signals. Each disk features intricate concentric circles (assigned to specific positions) and opaque and transparent segments. An absolute encoder detects the position of a shaft. An incremental encoder indicates shaft motion, which can provide information on speed, position, or distance.

Optical Encoder

An electromechanical device that sends an electrical output proportional to the input shaft’s angular position. The encoder disk has a series of opaque and clear segments. The transparent slits enable light from infrared diodes to pass through the disk and reach infrared receivers on the other side, creating an analog signal. This is converted into a digital signal, which is then sent to a processor.

Why Use Photo Chemical Etching?

Chemical etching can be used to produce encoder disks with slots as small as 1.2 times the thickness of the material. Openings can be as small as .006” on a .005” thick material. Etching can also create webs as small as 60% of the material thickness. On a .005” thick encoder disk, the webs can be as small as .004” wide.

Our etching process adds no extra stress to the metal. It only dissolves excess material, allowing the disks to stay as flat as the material with which we started. Chemical etching does not create any burrs on parts, so no obstructions are left behind.


  • Electronic equipment: Printers, computer mice, cutting devices, labeling machines, and industrial controls.
  • Medical equipment: Surgical robots, radiation systems, lasers, and magnetic resonance imaging.
  • Military and aerospace: Radar, aircraft throttle/thrust systems, instrumentation, and more in extreme environments.


We can produce encoder disks in the following materials:

  • Spring steel
  • Stainless steel
  • Most copper alloys including beryllium copper, brass or phosphor bronze

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