How to choose a front/back labeller
Start with container shape, label material and output requirement.
Technical guide
Label sensor guide for front and back labelling machines
Label sensors help the machine detect the label edge and control repeatable application. The right sensor depends on label material, backing and pack conditions.
On this page
Why sensor choice matters
A labelling machine must detect the label reliably before applying it to the pack. If the sensor cannot identify the label edge or gap, label position can drift or the machine can misfeed.
Sensor choice is especially important for clear labels, thin film labels, reflective labels and unusual backing materials.
- Opaque paper labels are usually simpler to detect.
- Clear labels may need ultrasonic or specialist sensors.
- Reflective or metallic finishes should be tested before specification.
Clear label detection
Clear labels can create a premium no-label look, but they can be harder to detect than opaque labels. The label and backing combination should be checked before machine selection.
Where possible, provide sample rolls or detailed material specifications so the correct sensor route can be confirmed.
- Label material and liner material.
- Gap size and label thickness.
- Bottle material and background at application point.
Product detection and label placement
The machine also needs to detect the container or product. Product sensors, label sensors and the machine control system work together to position the label.
Transparent containers, very dark containers or unusual shapes can affect product detection and should be mentioned early.
- Container colour and transparency.
- Shape, width and detection face.
- Position of front and rear labels.
What to send for sensor checking
A sensor decision is easier when the pack and label details are supplied together. This prevents a quote from assuming a standard opaque label when the project actually uses a more demanding material.
- Label sample or material specification.
- Photos of bottle and label position.
- Label gap, roll direction and backing details.
- Target speed and label tolerance.
Best next step: Best next step: send Lancing UK your container photo, label dimensions, label material and target output so the right labelling route can be checked before quote stage.
Related routes
Useful next pages
Use these pages to compare nearby machine routes, applications and buyer guides.
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Quick answers
Common questions
Do clear labels need a different sensor?
Often yes. Transparent labels may require a specialist sensor depending on the label and backing material.
Can sensor choice affect label accuracy?
Yes. Reliable label edge detection is important for repeatable label position.
Should I send label samples?
Yes. Samples are useful where labels are clear, reflective, very small or unusual.
Want help with this labelling requirement?
Send pack photos, label sizes, target speed and current line details. Lancing UK can help shortlist the best front/back labelling machine route.
Sensing decision matrix
Match the sensor to clear, metallic and layered label constructions
Choose the label sensor from the complete label-and-liner combination rather than the visible colour of the label. A consistent optical difference can make ordinary opaque labels straightforward to detect; transparent, metallised or non-uniform multilayer materials may need another sensing approach. Confirm the selection using the finished production reel, the actual detection line and the intended web speed.
| Optical detection | Is there a repeatable difference between label and liner at the sensing position, including printed and unprinted regions? |
|---|---|
| Ultrasonic detection | Does the full construction produce a stable distinction from liner-only gaps, including thickness variation and folded areas? |
| Combined approaches | Would a different detection principle suit part of a mixed material range better? Confirm the selected mode and setup for each approved job. |
| Detection position | Does the sensing line cross a cut-out, opening tab, internal fold or varying edge? Show that path on the label drawing. |
| Control interface | Confirm switching behaviour, response, connectors and machine input compatibility before treating a sensor as an interchangeable spare. |
Leuze’s label-carrier selection matrix explicitly distinguishes material combinations. Telemecanique Sensors’ ultrasonic label-detection example also covers transparent, metallic and irregular label formats. These are technology references, not statements about the sensors fitted to a Lancing machine.
Does metallic artwork always require replacing the sensor?
Not always. The answer depends on the sensing principle, label opacity, liner and position of the artwork relative to the sensor. Test the new production reel against the existing approved setup first. Do not choose a sensor only from the word “metallic” or copy settings from a visually similar label.
Why can a multilayer label create an extra trigger?
A detection line crossing a tab, fold or thickness transition may see more than one change within a label. The trial should identify the intended label boundary and verify the sensor output across the entire repeat. Changing sensitivity without understanding the construction can move the fault rather than solve it.
For the full material path, read booklet and peel-and-read application. For joined liner and restart handling, use reel and splice control.
Send a reel for sensing assessment
Include the container, both label constructions, target output and any existing line constraints.