Shedding Light on Different Types of Photoelectric Sensors

Photoelectric sensors have been around for more than 50 years and are used in everyday things – from garage door openers to highly automated assembly lines that produce the food we eat and the cars we drive.

The correct use of photoelectric sensors in a manufacturing process is important to ensure machines can perform their required actions. Over the years they have evolved into many different forms.

But, how do you know which is the right sensor for your application?  Let’s take a quick look at the different types and why you would choose one over another for your needs.

Diffuse sensors

    • Ideal for detecting contrast differences, depending on the surface, color, and material
    • Detects in Light-On or Dark-On mode, depending on the target
    • Economical and easy to mount and align, thanks to visible light beams
    • Shorter ranges as compared to retroreflective and through-beam sensors
    • IR (Infrared) light beams available for better detection in harsh environments
    • Laser light versions are available for more precise detection when needed
    • Mounting includes only one electrical device

Diffuse sensor with background suppression

    • Reliable object detection with various operating ranges, and independent of surface, color, and material
    • Detects objects against very similar backgrounds – even if they are very dark against a bright background
    • Almost constant scanning range even with different reflectance
    • Only one electrical device without reflectors or separate receivers
    • Good option if you cannot use a through-beam or retroreflective sensor
    • With red light or the laser red light that is ideally suited for detecting small parts

Retroreflective sensors

    • Simple alignment thanks to generous mounting tolerances
    • Large reflectors for longer ranges
    • Reliable detection, regardless of surface, color, and material
    • Polarized light filters are available to assist with detecting shiny objects
    • Mounting includes only one electrical device, plus a reflector
    • Most repeatable sensor for clear object detection; light passes through clear target 2X’s giving a greater change in light received by the sensor

Through-beam sensors

    • Ideal for positioning tasks, thanks to excellent reproducibility
    • Most reliable detection method for objects, especially on conveyor applications
    • Extremely resistant to contamination and suitable for harsh environments
    • Ideally suited for large operating ranges
    • Transmitter and receiver in separate housings

Fork sensors

    • Different light types (red light, infrared, laser)
    • Robust metal housing
    • Simple alignment to the object
    • High optical resolution and reproducibility
    • Fork widths in different sizes with standardized mounting holes
    • Identical mechanical and optical axes
    • The transmitter and receiver are firmly aligned to each other, yielding high process reliability

The next time you need to choose a photoelectric sensor for your manufacturing process, consider these features of each type to ensure the sensor is performing optimally in your application.

The Latest Trend in the Stamping and Die Industry

compact-sensor-blogOne trend we see today in many applications is the need for smaller low profile proximity sensors. Machines are getting much smaller and the need for error proofing has ultimately become a must for such applications in the Stamping and Die industry. Stamping Die processes can be a very harsh environment with excessive change overs to high speed part feed outs when running production. In many cases these applications need a sensor that can provide 5mm of sensing range however they simply do not have the room for an M18 sensor that is 45 to 50mm long. This is where the “FlatPack” low profile sensor can be a great choice due to their low profile dimensions.

Proximity sensors have proven time and time again to reduce machine crashes, part accuracy and proper part location. Sensors can be placed in multiple locations within the application to properly error proof “In Order Parts” (IO) for example detecting whether a punched hole is present or not present to ensure a production part is good. All of this adds up to reduced machine downtime and lower scrap rates that simply help a plant run more efficiently.

So when selecting proximity sensors and mating cables it is very important to select a sensor that A) mechanically fits the application and B) offers enough sensing range detection to reliably see the target without physical damage to the sensor. Remember, these sensors are proximity sensors not positive machine stops. Cables are also key to applications, it is important to pick a the proper cable needed for example an abrasion resistant cable may be needed due to excessive metal debris or a TPE cable for high flex areas.

Below both sensors have 5mm of sensing range:

M18vsFlatpack

Below both sensors have 2mm of sensing range:

M8vsFlatpack

You can see that in certain process areas “FlatPack” low profile sensors can provide benefits for applications that have space constraints.

For more information on proximity sensors click here.