ROBUST ENCODERS

What is a Robust Encoder?

A robust encoder is engineered to withstand harsh environments and substantial mechanical forces. These encoders typically feature enhanced bearings capable of managing axial and radial loads, as well as withstanding shocks and vibrations. Their housings are usually constructed from cast aluminum or steel, offering superior durability compared to stamped alternatives. Additionally, the electronics are encapsulated or protected to ensure reliable performance in humid or dirty conditions.

Types of Robust Encoders

Robust encoders can be classified based on their technology or their functional type. Technologically, they are divided into magnetic and optical encoders. Functionally, they are categorized as either absolute or incremental encoders. Each type offers distinct advantages depending on the specific application requirements.

By Technology

A magnetic encoder utilizes magnetoresistive technology to detect the position, speed, or direction of a rotating shaft or linear motion. It consists of two primary components: a magnetic ring and a polarized sensor. The magnetic ring is mounted to the rotating shaft or moving part, while the sensor remains stationary. The sensor detects changes in polarity and emits a square wave signal. Due to its robust composition and properties, magnetic technology is ideally suited for humid and dirty environments, as well as for applications subjected to high levels of shock and vibration.

An optical encoder converts motion or position into a digital signal by detecting changes in light. It typically comprises a rotating disc with evenly spaced slots or markings, alongside a light source and sensor that read these slots or markings as the disc rotates. Due to its composition and properties, optical technology is generally more cost-effective and is best suited for ultra-high-resolution applications.

By Type

Incremental Encoders
Incremental interfaces communicate with the control system through three or six channels (A, B, Z, and their complements /A, /B, /Z), operating within a voltage range typically from 5-30 VDC.

Typically, incremental encoders:

• Are more commonly used to determine speed and direction of rotation.
• Provide relative position information.
• Require a reference point to determine absolute position.
• Lose positional data when power is lost.
• Are generally less expensive and simpler than absolute encoders.

Absolute Encoders
Absolute interfaces encompass a wide range of field bus communication protocols, including Ethernet, DeviceNet, CanOpen, SSI, and Parallel. Proprietary interfaces such as EnDat and Hyperface are less commonly used in robust or heavy-duty applications.

Typically, absolute encoders:

• Provide a unique position value at every point.
• Retain position information even after a power loss.
• Are suitable for applications requiring high reliability and accuracy.

How Does a Robust Encoder Work?

As the shaft turns, the encoder generates square wave signals using either magnetic or optical technology. Robust encoders, however, are designed to provide reliable feedback even in challenging conditions, including vibration, moisture, dust, and temperature fluctuations.

Robust Encoder Uses & Applications

• Nuclear, Mining, or Metals: Handle high shock, intense vibrations, and significant temperature fluctuations.
• Pulp & Paper Industry: Tolerate high levels of paper dust and high humidity.
• Food and Beverage: Stainless steel versions are used to withstand pressure cleaning and harsh hygiene conditions.
• Marine Ports & Coastal Areas: Resist salt sprays, rain, humidity, and extreme temperature fluctuations.
• Woodworking & Sawmills: Operate reliably amidst high levels of dust and vibration.

Advantages of Robust Encoders

Enhanced Resistance to Shock and Vibration: Designed to endure significant physical movement, robust encoders maintain reliable performance even in challenging conditions.

Ideal for Harsh Environments: These encoders exhibit high resistance to extreme conditions such as high humidity and temperature variations, ensuring dependable operation in severe environments.

High Durability: With their robust construction and, in some cases, the absence of bearings, these encoders offer long operational lifespans and require less frequent maintenance and replacement.

Superior Encapsulation: Protected or encapsulated electronics shield internal components from liquids and dust, enhancing reliability and longevity.

Things to Carefully Consider

Cost: While robust encoders may have a higher initial purchase price, their superior durability in demanding applications often outweighs this cost. The potential savings from reduced downtime and maintenance expenses can be substantial.

Complexity: Robust encoders, such as those with bearingless or hollow shaft designs, might seem complex initially. However, adhering to key guidelines and maintaining proper eccentricity and alignment can greatly enhance their performance and benefits.

Weight and Size: The use of advanced materials and additional components in robust encoders can result in increased size and weight. Proper system design, including adequate space planning and support structures, is essential to accommodate these factors.

An Avtron representative can assist in addressing these considerations to ensure your application operates smoothly and efficiently over the long term.