Position sensors

Position Sensors: Precise Position Detection for Perfect Motion Control

Position sensors represent the most advanced form of precise position detection, allowing machines to run perfectly and without error. The way a sensor position device works together with a position sensing system is clearly superior to an ordinary object detection sensor. If you are looking for an urgent replacement part, SCMA can cross-check the specification through our online service to keep your plant at zero downtime.

What Is a Position Sensor? The Heart of an Automatic Control System

A position sensor converts the mechanical position of a machine part into an electrical signal for the control system. These devices differ from an ordinary object detection sensor that only reports whether a workpiece is present or not: industrial-grade position sensors can determine distance, angle of rotation or linear position down to micron level. An accurate sensor position device allows the position sensing system to coordinate robot arms and pneumatic cylinders perfectly, decisively reducing scrap on the production line.

The Engineering Principles Behind Position Sensing

Position sensing relies on several physical principles to achieve accuracy. The internal circuit may use changes in a magnetic field (magnetic/Hall effect), the reflection of light (optical), changes in capacitance (capacitive) or ultrasonic waves. The processing circuit of the position sensors takes these changes and calculates the target distance in real time. Choosing the sensor position technology that matches the workpiece material allows the object detection sensor to feed coordinate data into the PLC quickly, meeting the demands of a modern position sensor system.

Classifying Object Detection Sensors Used to Report Position

Machine mechanisms move in many different ways, so the choice of object detection sensor must be based mainly on the direction of travel of the part. Identifying the right sensor position type reduces mistakes in system design.

Linear Position Sensors

This type mainly detects movement along a straight line, making it suitable for fitting into pneumatic cylinders, hydraulic cylinders or plastic injection platens. Using a linear position sensor allows fine control of cylinder stroke. Technicians can use this kind of object detection sensor to check workpiece thickness on a conveyor accurately, meeting the needs of a position sensing system that demands high stability.

Rotary Position Sensors (Encoders)

This type detects angular rotation, making it suitable for measuring motor shaft revolutions or the joints of an industrial robot arm. The engineering team must select the position sensors format that matches the on-site mechanism in order to reduce measurement error. Applying this group of object detection sensors lets the control system manage speed and angle of rotation flawlessly.

Failure Analysis When Sensor Position Readings Drift

Drifting sensor position readings are a constant headache for maintenance teams. Analysing the true root cause helps prevent serious damage to the position sensing system in good time.

Main Causes and How to Prevent Drift

The main problem is accumulated vibration, which loosens the bolts at the mounting point. Site temperatures above the rated limit can also cause the circuit of the object detection sensor to report distorted values. Maintenance technicians must set a strict calibration interval for the position sensor. Looking after the object detection sensor correctly prevents machines from operating out of sequence and parts from colliding and being damaged.

Technical Specifications for Selecting the Right Model

Ordering a replacement object detection sensor requires careful analysis of the engineering data. Understanding the specification of the position sensor prevents ordering the wrong model and finding it unusable.

• Engineers must consider the resolution required by the position sensing system, to avoid readings that are too coarse
• Check repeatability, which matters even more than accuracy in automated assembly work using a sensor position device
• Check the IP rating: environments with splashing coolant mist require IP67 or higher to protect the internal circuit
• Confirm the mounting distance of the object detection sensor against the free space in front of the machine, to prevent impact during operation

Output Signal Standards and Connection to the PLC

Wiring the signal from the object detection sensor into the control system must follow the standards. Choosing the wrong communication format for the object detection sensor will make the PLC read distorted values.

• The 4-20 mA analogue signal is highly stable and resistant to noise, making it suitable for running position sensors cabling over long distances around the plant
• The 0-10 V signal suits short runs at the control cabinet; technicians must watch for voltage drop if the sensor position cable is run too far
• Current technology supports the IO-Link protocol, letting engineers pull operating status data from the position sensor for real-time analysis
• IO-Link allows the parameters of the position sensing system to be set over a single signal cable, reducing wiring complexity at the cabinet

Summary

Deploying position sensors raises the standard of your machinery to the highest level of accuracy. Choosing the sensor position device that matches the application lets the position sensing system work seamlessly, and scrap caused by assembly errors disappears with a high-quality object detection sensor. SCMA is ready to act as your online engineering adviser so you can cross-check replacement part specifications immediately.

Looking to Buy Position Sensors? Order from SCMA Today!

SCMA provides full online engineering support for position sensors. Photograph the nameplate of your existing object detection sensor and send it through our chat channel: our engineering team is on standby to cross-check the sensor position specification immediately, with no waiting for a technician to visit. We hold ample stock ready for express delivery from our Chonburi and Lamphun branches, professionally supporting the zero-downtime policy of your plant's position sensing system.

Frequently Asked Questions about Position Sensors

What is the difference between potentiometer and magnetostrictive linear position sensors?

The potentiometer type uses a contact wiper sliding along a resistive track. It is economical but has a limited service life because of mechanical wear. The magnetostrictive type uses non-contact magnetic field technology, withstands impact and lasts far longer, meeting the needs of object detection sensor applications and a position sensing system that requires high stability.

The area around the machine is heavy with metal dust — which technology should be chosen?

Avoid optical and magnetic sensors: metal dust obscures the lens and is attracted to the sensor position device. We recommend considering inductive position sensors, which are designed specifically to withstand dust and industrial oil films, allowing the position sensor to work for a long time.

Is repeatability really more important than accuracy when programming a robot arm?

Yes. Repeatability of the same position matters most in automated assembly work. If the object detection sensor repeats steadily, engineers can program an offset in the PLC to compensate for deviation, and the position sensing system will work in full coordination. Choosing a good object detection sensor therefore means looking at this value first.