Web guide edge sensors · Ultrasonic vs infrared vs mechanical, fork width and measuring range, analogue output, linearity, air conditions, teach-in
A web edge sensor measures the lateral position of a moving web's edge so that a web guide can steer it, as with the U-shaped fork sensor pictured straddling the edge of a film web. Ask three things first: which sensing principle suits the material (ultrasonic, infrared or mechanical), the measuring range and resolution around the edge, and the output signal and supply your guide controller expects.
Edge sensors for web guiding on film, paper, foil, textile and nonwoven lines: ultrasonic and infrared fork sensors, retroreflective sensors and mechanical edge feelers. Complete web guide systems and actuators, line and print-mark sensors, CCD camera systems, and general photoelectric switches are outside this page.
CNFX editorial research · Sources checked October 11, 2026 · 4 sources
Erhardt+Leimer groups its edge sensors as ultrasonic, infrared and mechanical. Its ultrasonic FX 42 has a ±3 mm field of view and fork widths of 30, 60 and 124 mm, and the FX 52 ±10 mm; its retroreflective infrared FR 52 has ±10 mm and 0.02 mm resolution; its transmitted-light infrared FR 46 has ±2.5 mm and 0.01 mm; its mechanical/pneumatic FM 30 covers ±65 mm. [2]
SNT says its ultrasonic fork barriers are much less sensitive to dirt and dust than optical sensors and handle transparent materials such as foils. [1] di-soric describes its USGT ultrasonic fork sensors as suited to transparent films and printed paper, with highly reflective surfaces unable to falsify the signal, and as resistant to dirt. [3]
The supplier linked to this page lists an ultrasonic sensor with 5 mm detection range, 0.1 mm accuracy and 1 ms reaction time, and a photoelectric sensor with 5 mm range and 0.02 mm accuracy using 100K-frequency carrier coding so ambient light does not affect it; both are listed for opaque and transparent film. [4]
Give the supplier the web material (transparent, printed, reflective, porous or textile), web speed, required guiding accuracy, the space available at the edge (fork depth and opening), dirt, dust and temperature at the sensor, and the guide controller's input (voltage, current or digital).
02
Set the measuring range, output and installation
SNT's UPF-A ultrasonic fork sensors output 0–10 V as a function of how much of the receiver the web covers, over a detection width of about 8 mm (±4 mm) on 30 and 60 mm forks or about 13 mm (±6.5 mm) on 40 and 70 mm forks. They specify resolution of about 0.1 mm at 20–80% covered, linearity of ≤2% or ≤4% FS at 10–90% covered, 8–30 V DC supply, IP67, 0–60 °C operation and an M12 connector. [1] di-soric's USGT range likewise gives 8 mm or 13 mm working ranges for fork openings of 30–70 mm, with voltage or current outputs. [3]
SNT notes that air conditions change the ultrasonic signal at a given edge position: about 1.2% signal reduction for 10% higher relative humidity, about 1.3% increase per 10 mbar higher air pressure and about 1.6% reduction per 100 m higher altitude. Teach-in sets the fully covered and fully open outputs to remove these shifts and the offset from partly sound-transparent materials such as textiles. Running the web plane within 7 mm (or 5 mm on the wider-range forks) of the transmitter or receiver shifts the reading by up to ±0.3 mm (or ±0.5 mm); further away the shift is ≤±0.1 mm. [1]
Editorial calculation: on an SNT 30/8 fork, 10 V over about 8 mm is roughly 1.25 V per mm, so its 0.1 mm resolution corresponds to about 0.125 V; a 30% rise in relative humidity, at about 1.2% per 10%, would shift the signal by about 3.6% unless re-taught. [1]
03
Compare what suppliers offer
The supplier linked to this page lists ultrasonic, photoelectric and colour-line web guide sensors and CCD sensors; its card links to the page reviewed.
Ask any supplier for the sensing principle, fork width and depth, measuring range, resolution and linearity, response time, output signal and supply, temperature and ingress ratings, housing material and connector, and compatibility with your guide controller.
04
Trace the sensor parts
This is a functional reference built from the sources cited; it is not one maker's specification.
Fill the specification fields with values for your line
An edge sensor quotation needs values for your web and guide. The table explains each field, gives published values where a reviewed source states them, and says what to obtain from the supplier.
Field
What it means and published values
Ask the supplier for
Detection Range (mm)
e.g. ±4 or ±6.5 mm ultrasonic; ±10 mm infrared; ±65 mm mechanical. [1][2]
Range at your fork.
Accuracy (mm)
Resolution e.g. about 0.1 mm; 0.02 mm; 0.01 mm. [1][2]
Explore company information and manufacturing capabilities, then discuss the scope of your project with a relevant supplier.
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Compiled and source-reviewed by the CNFX editorial team.
Published product pages show what a company offers, not tested performance. Confirm the legal seller, factory and scope for your order. How we source and review
· Page last updated 13 October 2026
Buyer questions
Which edge sensor works on transparent film?
SNT and di-soric both describe their ultrasonic fork sensors as suited to transparent foils and films, and SNT says ultrasonic forks are much less sensitive to dirt and dust than optical sensors. [1][3]
How large is an edge sensor's measuring range?
SNT lists about ±4 mm or ±6.5 mm for its ultrasonic forks; Erhardt+Leimer lists ±10 mm for infrared and ±65 mm for a mechanical/pneumatic sensor. [1][2]
Why does an ultrasonic edge sensor need teach-in?
SNT says humidity, air pressure and altitude change the signal, and partly sound-transparent materials add an offset; teach-in resets the covered and open levels. [1]
Sources and what still needs a direct check
Sources checked 2026-10-11. SNT, di-soric and Erhardt+Leimer make edge sensors; Precision Converting is the supplier linked to this page.
