Experiencing issues with the movement range of your machine causing deviations that negatively affect product quality? This problem can be resolved by installing a Linear Encoder, an essential device that ensures precise control. In this article, SCMA, a provider of measurement tool and automation system solutions, will take you through the working principles, types, and how to select linear displacement sensors to properly apply them and enhance performance in industrial factories.
What is a Linear Encoder?
A Linear Encoder is a sensor device used to measure and convert linear motion positions into digital or analog signals. The operation of this type of sensor accurately determines the distance, direction, and speed of the machine at the micron level, making it a crucial component for feeding data back to the control system to reduce production errors.
How a Linear Encoder Works
Understanding the basic working principle of a Linear Encoder or linear distance measuring sensor will help users install and configure it effectively. The following are the main components and basic operating procedures.
Scale Strip
The scale strip is an important component that must be installed parallel to the machine's movement direction. On the scale strip, there are detailed markings or distance codes, whether in the form of light grooves or magnetic strips. The material used for the scale has a significant impact on the durability and accuracy of the control system's position measurement.
Readhead (Sensor)
The readhead or sensor is installed on the moving part of the machine and runs continuously along the scale strip during linear movement. A good readhead must be able to quickly send light or a magnetic field to the scale to receive reflected signals accurately.
Signal Conversion
When the readhead receives the reflected signal, the internal circuit converts these physical changes into electrical signals. The resulting pulse signals are quickly sent to the control unit or PLC system, allowing the system to know the actual position of the machine in an instant.
Position Detection
After the control unit receives the electrical signal, the system processes it to accurately determine the position, distance, and speed of movement. These detailed data help the drive motor adjust the distance and completely eliminate mechanical errors.
How many types of Linear Encoder are there?
The classification of Linear Encoder can be divided into 2 main types according to the signal generation method and the way of reading position data, which users must consider selecting to match the purpose of the automatic control system
1. Incremental Linear Encoder (Step-by-step type)
This type of encoder generates continuous pulse signals when moving across the scale. The operation requires referencing the starting position (Home Position) each time the system is turned on. It is suitable for speed control or distance measurement tasks that can be reset in case of a power outage
2. Absolute Linear Encoder (Complete Position Specification type)
This system assigns a unique data code to every position along the straight line, allowing the actual position value to be read immediately without returning to the reference point even after just turning on the machine. It is considered a measurement device for distance that meets the needs of important machinery requiring high safety and prevention of waste in the production line
Maintenance of Linear Encoder
In order for the Linear Encoder to transmit signals accurately and prevent the position control system from malfunctioning, Preventive Maintenance or preventive maintenance is an essential step.
1. Cleaning the Scale Bar and Reader Head
Dry compressed air free of oil mist should be used to blow away dust from the scale bar and reader head. If there are sticky residues, gently wipe them in the same direction using a lint-free cloth soaked in isopropyl alcohol. A warning is that corrosive chemicals must never be used, as they will damage the equipment surface.
2. Inspection of Installation and Alignment
Regularly check the distance (Air Gap) between the reader head and the scale bar to ensure it conforms to the standard value of the respective model, to prevent the reader head from failing to capture the signal. Also, check the mounting points and tighten the screws securely to reduce errors caused by machine vibrations during operation.
3. Inspection of Electrical System and Signal Cables
Always inspect the condition of the cables and connectors. There should be no cracks, rust, or moisture that may cause signal loss. It is important to ensure the grounding system of the shielded signal cables is complete, to prevent electrical interference from adjacent motors that may affect measurement accuracy.
4. Care of Dust Seals and Protective Devices
For enclosed sensors, check the condition of the dust-sealing rubber to ensure it remains flexible and intact. If it is to be used in areas with flying metal chips or large amounts of coolant, it is recommended to install additional protective covers to extend the service life of the measuring device.
Application of Linear Encoder in Industry
With the ability to convert movement into high-precision electrical signals, Linear Encoder is widely applied in various industries to enhance competitive capabilities.
CNC Machines and Metal Milling Machines
In the manufacturing industry, this sensor device is used to control the movement of the table axis or cutting head with micrometer-level precision. The accurate position data transmission helps to mill metal parts perfectly according to the specifications and reduce the rate of waste.
Robotics System
Robotics technology requires precision in handling parts. Using the linear distance measuring sensor helps to measure the distance and movement of the robotic arm axis perfectly. The control system can safely and quickly command the robot to move to the target position.
Automation in Production Line
For controlling the production line, this device is used to check the position of the workpiece or the moving station on the slide rail. When the PLC system receives the correct position data, the coordination between each production station operates smoothly and with maximum efficiency.
Advantages of Linear Encoder
Investing in the installation of a Linear Encoder in the motion control system of an industrial factory provides benefits and advantages that directly impact business profits as follows
High Precision at Micron Level
The first advantage is the ability to accurately measure position, distance, and linear velocity at the micron or nanometer level. This high level of precision meets the requirements of modern production processes that demand the highest standards of accuracy to deliver excellent quality products
Reduces Mechanical Errors (Backlash)
Installing sensors to directly measure the actual position of the workpiece or moving axis helps eliminate errors caused by backlash or wear of screws and gears. The system adjusts the position in real-time, making motion control more stable
Durable Against Industrial Environments
New devices are designed to be stable and durable against obstacles in the factory, including dust, oil stains, and vibrations. The strong structure allows the sensor to continuously feed data back to the control system without interruption, even if the working environment is harsh
Reduces Downtime
When the control system accurately knows the true position of the machine, the risk of collision or mechanical damage is greatly reduced. This results in reduced production line downtime, helping operators manage production plans efficiently and cost-effectively
How to Choose a Linear Encoder
Considering the appropriate selection of a Linear Encoder for the machine and control system is a key factor in improving the production process. Engineers should pay attention to the following guidelines:
Determine the Measuring Type: Choose between an Incremental Encoder for relative distance measurement or an Absolute Encoder if the application requires immediate knowledge of the actual position coordinate upon startup.
Evaluate Resolution and Measuring Length: Check the stroke to cover the actual movement, and select the resolution level that matches the required accuracy standard of the workpiece.
Check the Output Signal Type: Check the specifications of the existing PLC or control board to ensure compatibility with NPN, PNP, or Line Driver signals to ensure correct data communication.
Consider the Environment (IP Rating): If the installation location has oil mist or dense dust, choose a model with an IP65 or higher protection rating to extend the service life of the measuring device and ensure value for money.
Consultation and System Design Services from SCMA
Along with selecting the correct specifications, having experts to guide you in system integration is a crucial key. SCMA is ready to provide the following comprehensive services:
Project and Solutions: Our engineering team is ready to design systems and select measuring devices that are fully compatible with your CNC machines or automation systems.
Installation and Calibration Services: Ensure maximum accuracy with installation services provided by our technical team, along with calibration work to ensure measured values meet international standards.
Comprehensive After-Sales Service: Our team is ready to provide close support for maintenance and electrical system checks to prevent machine downtime problems.
Summary
Linear Encoder is an essential device that cannot be missed in enhancing the accuracy of motion control systems in the industry. Understanding the basic working principles and selecting the appropriate type will help reduce errors and sustainably improve product quality. If your factory is looking for high-quality linear measurement sensors, SCMA, as an expert in measuring instruments and automation systems, is ready to be your partner, providing consultation and delivering the best solutions for you.
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If you want to buy a Linear Encoder, you can purchase it from SCMA today!
Investing in the correct measurement technology directly affects reducing costs and increasing profits for the business. SCMA Co., Ltd. (SCMA) is a distributor of selected industrial measuring instruments and equipment, specifically from world-leading brands. We have a team of engineers ready to provide consultation, recommend the selection of linear measurement sensors, as well as complete automated system solution services to professionally meet the technical needs of all customers.
Frequently Asked Questions
What is the difference between a Linear Encoder and a Rotary Encoder?
A Linear Encoder is used to measure linear movement, while Rotary Encoder is used to measure the angle or rotational speed of a motor's shaft
Can it be changed from Incremental to Absolute?
It can be done, but you must first check the original control board or PLC to see if it supports reading Absolute signal codes. If it supports, you can change it to improve performance
Do dust and oil stains affect the operation of the scale?
It directly affects the optical system models because they block the light reflection. It is recommended to choose magnetic system models or those with a high IP rating when using in environments with a lot of dust
How often should the reader head be cleaned?
It depends on the working environment. For general factories, it is recommended to check and use dry air to gently blow and clean during the monthly preventive maintenance cycle
If the signal cable is broken, can it be connected by oneself?
It is not recommended to connect the signal cable yourself because it may change the resistance value and cause interference signals. It is recommended to replace the cable or have an expert engineer from SCMA perform the repair for maximum accuracy
