Manufacturers need encoders, but they don’t really want to think about them. Encoders are arguably one of the most necessary sensors in manufacturing, but many aren’t sure what to consider when installing them.

Encoders are sensors that translate motion into an electrical signal that can be interpreted by a control device. They provide data about position, angle and rotation counts. This data can be used to determine speed and position, making encoders the perfect solution for accurate position detection in industrial automation.

Encoders use different types of technologies to create a signal, including mechanical, magnetic, resistive and optical. For example, in optical sensing, the encoder provides feedback based on the interruption of light.

There are two main types of encoders — absolute and incremental — each providing different kinds of information. Absolute encoders provide a unique position signal that describes the specific location of a system within its range of motion, while incremental encoders produce a pulsed signal as their position changes, providing fast and precise feedback.

Figure 1: Encoders are arguably one of the most necessary sensors in manufacturing. Source: SICK

Figure 2: There are two main types of encoders — absolute and incremental. Source: SICK

Figure 3: Encoders are sensors that translate motion into an electrical signal that can be interpreted by a control device. Source: SICK

Selecting the right incremental encoder for an application

The position of incremental encoders is defined by the number of pulses per rotation. The outputs of incremental encoders, which can be either a square or a sine/cosine wave, are transmitted to a control unit for each rotation. By counting the pulses from the output data, the current position can be determined.

Considerations for selecting incremental encoders

So what incremental encoder will work best for an application? Selecting the right incremental encoder for a specific application involves considering several key factors.

• Type of motion: Determine whether the motion is unidirectional or bidirectional.
• Environmental conditions: Consider the environmental conditions of the application, such as temperature, moisture, shock, vibration and contamination. These conditions can influence the choice of sensor (optical, magnetic, inductive).
• Mechanical design and mounting process: The mechanical design of the system, including how the encoder will be mounted, is another important factor.
• Resolution: The resolution of the encoder (pulses per revolution or counts per revolution) is crucial as it determines the precision of the feedback. The required resolution will depend on the specifics of the application.
• Physical form factor: The physical size and shape of the encoder can be a crucial factor, especially in applications where space is limited.

The selection of the right incremental encoder is a critical decision that can significantly impact the efficiency and accuracy of the application. By considering factors such as the type of motion, environmental conditions, mechanical design, resolution and physical form factor, users can ensure that they choose an encoder that best fits their needs.

Remember, incremental encoders are ideal for applications where relative position, speed or direction of movement is important. Whether it’s for positioning and motor speed feedback, motor control systems, tension control, cranes and robotics, or CNC machines, incremental encoders provide precise and fast feedback, making them an indispensable tool in industrial automation.

All about hollow shaft encoders

A hollow shaft incremental encoder is a type of rotary encoder that provides velocity feedback and is typically used in positioning and motor speed feedback applications. These are often referred to as HS35 class and HS25 class encoders.

Hollow shaft encoders are often utilized because they are more compact than solid shaft encoders, making them ideal for applications where space is limited. These encoders can be directly mounted to a motor shaft and affixed using a flexible tether or torque arm to prevent the encoder from rotating. This makes the installation, positioning and alignment easier.

Hollow shaft encoders can be used in a variety of industries, including manufacturing, automotive and robotics. They are commonly used in applications where a solid shaft encoder is not practical, such as in large rotating machinery or when a shaft must pass through the encoder.

Hollow shaft encoders are more forgiving in terms of shaft sizing, especially in length. They can be mounted onto a wide range of shaft sizes. The hollow shaft insulation acts as a galvanic separator and thermal decoupler. It reliably eliminates shaft currents, bearing corrosion and wear while keeping down encoder temperature.

Hollow shaft encoders offer moderate resistance against shock and vibration. This is particularly beneficial in industrial environments where machinery often experiences significant amounts of physical stress.

Without the need for an extra coupling, hollow shaft encoders have a smaller installation profile. This can be advantageous in applications where space is limited. Hollow shaft encoders provide a strong foundation for speed and RPM feedback. This is crucial in many applications where precise speed control and feedback are required.

Get an encoder

SICK’s DFS20/DFS25 and DGS80 encoders are built or stocked in Minneapolis, Minnesota. That means users don’t have to wait weeks — or even sometimes months — to get an encoder. SICK’s incremental encoders can ship from their factory so customers can receive what they need in a matter of days, not weeks.

DFS20/DFS25: Made in the USA for high performance and reliability

· High resolution: more precise positioning for applications that require high accuracy.

· Reduced costs: Spare parts inventory requirements are reduced because a single programmable DFS2x encoder can be used across a variety of applications.

· Reduced machine downtime: Wide operating temperature range and high tolerance of shock and vibration reduce machine downtime.

DGS80: The new generation of large bore encoders in the HS35 class

• Easy installation: Universal tethers and reliable clamping ring help to reduce set-up time.
• Simplicity: Large bore eliminates the need for special couplings and allows simple integration into numerous applications.
• Space saving: Compact design allows for seamless integration in designs where space is limited.
• High resolution: Gain high resolution of up to 8,192 pulses per revolution, capable of measuring speeds up to 3,600 revolutions per minute.

Figure 4: The large resolution range means the encoder is well-suited for many different industrial applications. Source: SICK

The DGS80 at work

How can the SICK DGS80 encoder impact day-to-day work in industrial applications? It is effectively used in various industrial applications to improve efficiency and precision, making a significant difference in various industrial automation applications.

The large resolution range means the encoder is well-suited for many different industrial applications such as printing, scanning, elevator speed control and speed measurement of AC motors.

For example, the DGS80 encoder is used to detect the position of overhead traveling crane gears. This helps in precise positioning and movement of the crane, improving safety and efficiency.

For those looking to control speed on conveyors, the DGS80 encoder can be used to calculate belt speed and running direction. This helps in maintaining the correct speed and direction of the conveyor belt, ensuring the smooth flow of materials.

Figure 5: Solid shaft encoders are a type of encoder that have a solid center that rotates with the shaft. Source: SICK

Solid shaft encoders

Solid shaft encoders are a type of encoder that have a solid center that rotates with the shaft. This type of encoder offers excellent mechanical stability and robustness for applications where accuracy and durability are critical. Solid shaft encoders are typically used in heavy machinery, industrial equipment and high-speed applications.

These encoders are mounted directly onto a solid shaft, providing a compact and reliable solution for position sensing. They are widely used in various industrial applications, such as robotics, machine tools and automation systems.

One of the main factors to consider when choosing between hollow shaft and solid shaft encoders is the accuracy requirements of the application. Solid shaft encoders offer better accuracy and are often better suited to applications that require high resolution feedback. However, the installation of solid shaft encoders may require additional steps such as coupling and alignment, which can increase installation time and effort.

Figure 6: Encoders on conveyors offer significant advantages in material handling and packaging systems. Source: SICK

Advantages of encoders for conveyors

Encoders on conveyors offer significant advantages in material handling and packaging systems. They provide precise control over the conveyor’s motion, enabling accurate positioning and speed management. This precision enhances the efficiency and productivity of the system, optimizing operations and reducing waste.

Encoders also contribute to increased safety by providing real-time feedback, which can be used to prevent accidents and malfunctions. They offer high accuracy across the entire length of the conveyor belt, ensuring consistent performance. Even over long distances, encoders maintain their performance, making them suitable for large-scale conveyor systems.

With their ability to support adjustable-height transfer systems, encoders bring flexibility to variable-height conveyors. Encoders play a critical role in enhancing the performance, safety and efficiency of conveyor systems.

Primarily, encoders used on conveyors are classified as absolute and incremental based on functionality. The absolute rotary encoder provides a unique code for each shaft position, offering precise position tracking. Incremental rotary encoders, on the other hand, output pulses correlating to the amount of rotation, allowing for the calculation of position through pulse counting.

The critical role of encoders on conveyors

Encoders play a crucial role in conveyor systems used in material handling and packaging. These functionalities of encoders help in achieving efficiency, precision and coordination in conveyor systems used in material handling and packaging. Here’s how they contribute.

Motion feedback

Encoders, when combined with measuring wheels, provide vital motion feedback. The wheel rides on the conveyor belt or material surface, and as it turns, the rotating shaft creates electrical pulses that the encoder sends to the controller.

Precise timing

Material transported by conveyors relies on encoder feedback for coordinated functions like cut-to-length, container filling, product inspection/rejection and pick-and-place. Once the encoder has sent a predetermined number of pulses to the control system, it activates the cutting device, dispenser, camera, actuator or pick-and-place robot.

Cut-to-length functions

In cut-to-length functions, the encoder generates a fixed number of pulses, which then determine the length of travel. When the encoder has sent the predetermined number of pulses to the control system, it activates the cutting device.

Conveyor speed and direction

Encoder feedback can be used to monitor belt speed and direction, as well as the position of objects on the conveyor.

Integration with vision systems

For many conveyor applications, incremental encoders are used in tandem with vision sensors to aid with operations such as product marking, inspection, and pick and place. The function of the encoder is to indicate belt speed, with the rate of encoder pulses generally equivalent to the resolution requirements of the receiving device.

Surface-mounted conveyor feedback

An effective means of obtaining conveyor feedback is to read directly from the belt itself, using a precision measuring wheel attached to a rotary incremental encoder.

For more information on encoders, visit the SICK website.