Sick NT6-03022 | NT6 Contrast Sensor — 9mm, Red/Green LED, 560nm, 1.5×5mm Spot, 10–30VDC, IP67, 2m Cable, Analogue Output

Overview

The Sick NT6-03022 is a contrast sensor from SICK's NT6 series — a device purpose-built for detecting colour mark and print registration differences on packaging materials, labels, and printed substrates where inductive or standard photoelectric sensors cannot discriminate between materials of similar reflectivity but different colour.

At 9mm operating distance with a 1.5 × 5mm light spot and dual-colour red/green LED illumination at 560nm, it reads the contrast difference between a printed mark and its background and outputs an analogue signal proportional to the detected contrast level.

The choice of red and green LED illumination — with an effective wavelength of 560nm — is deliberate.

The 560nm wavelength sits at the boundary between red and green in the visible spectrum, which is where the human eye is most sensitive and where the contrast between printed colours is often most pronounced.

For label detection, registration mark identification, and packaging integrity checks where the sensor must distinguish a yellow mark on a white background (a notoriously difficult detection task for single-colour sensors), the combined red/green illumination at 560nm provides the spectral sensitivity to resolve contrasts that a single-wavelength sensor would merge into a uniform signal.

The 1.5 × 5mm elliptical light spot is not a generic spot — its dimensions are matched to the typical width and height of registration marks on packaging film and labels.

A spot that is too large samples mark and background simultaneously, diluting the contrast signal. 

A spot that is perfectly sized to the mark's dimension maximises the signal swing between "on mark" and "off mark" positions, directly improving detection reliability at high line speeds.

Key Specifications

Analogue Output: 0.15–6V — Reading Contrast Rather Than Switching On It

Most photoelectric sensors produce a binary switching output: on or off, based on whether the received signal crosses a fixed threshold. The NT6-03022's 0.15–6V analogue output takes a different approach — it provides a continuous voltage proportional to the contrast level at the sensing point.

At minimum contrast (mark and background indistinguishable), the output sits near 0.15V. As the difference in reflectivity between mark and background increases, the output rises toward 6V.

This analogue characteristic gives the connected control system two capabilities that binary sensors cannot provide. First, the controller can read the contrast signal in real time and use it to trigger switching at any threshold it defines in software — the sensor does not impose a fixed trip point.

Second, by monitoring the signal level across production, the controller can detect gradual degradation in print quality (fading marks, ink variation, substrate changes) as a trend in the analogue output rather than waiting for a binary sensor to miss a detection event entirely.

For high-speed packaging lines where missed mark detections translate directly into misprinted or misaligned product, this continuous monitoring capability is the feature that distinguishes contrast sensors from conventional photoelectric approaches.

Zinc Diecast Housing — Industrial Durability in the Print Zone

The zinc diecast housing of the NT6-03022 is a deliberate choice over plastic for the machine environment where contrast sensors live: directly adjacent to packaging film, labels, adhesive coatings, and the occasional cleaning solvent or ink overspray that accompanies printing and labelling operations.

Zinc diecast housing provides dimensional stability under temperature cycling, resistance to mechanical damage from tooling contact or component impact, and IP67 sealing integrity that plastic snap-fit housings cannot consistently maintain after multiple installation/removal cycles.

At 80 × 30.4 × 64mm and approximately 540g with cable, the NT6-03022 is a substantial sensor by contrast sensor standards — appropriate for permanent installation on fixed machine frames rather than robotic tool-tip mounting where mass constraints apply.

The 2-metre factory-installed cable simplifies installation in standard machine panels without the risk of connector contact resistance that field-connectorised versions can develop after repeated disconnection.

Successor and Replacement

SICK discontinued the NT6-03022 (part no. 1005822) and designated the KTX-WB9114125UZZZZ as its successor. The successor carries comparable contrast sensing capability in the current KTX platform with updated electronics and connectivity options.

For applications where the NT6-03022 is already installed and a surplus replacement unit is required for maintenance stock, the NT6-03022 remains compatible with the existing wiring and signal conditioning as long as the machine interface accepts the 0.15–6V analogue output range.

FAQ

Q1: The output is analogue 0.15–6V — what does this connect to in a typical packaging machine?

The 0.15–6V analogue output connects to a dedicated contrast sensor input on the machine's registration controller, or to a standard analogue input on a PLC with user-configurable threshold.

Most registration control systems provide a contrast input specifically designed for analogue sensors of this type — the input includes an adjustable trip-point comparator that converts the analogue contrast level to a binary registration pulse for the servo or axis controller.

In systems using a standard PLC analogue input, the threshold is set in software.

Q2: How is the NT6-03022 taught to distinguish the specific mark from the background?

SICK's NT6 series offers teach-in and manual potentiometer sensitivity adjustment options depending on the variant.

For the NT6-03022, the sensitivity adjustment allows the operator to optimise the sensing threshold for the specific mark/background contrast combination being detected. Place the sensor over the background, record the output level, then place it over the mark and record the second level — the controller's threshold is set between these two values with a margin that accommodates substrate variation and transport vibration.

Q3: The sensing distance is 9mm with ±2mm tolerance — what does the tolerance mean in practice?

The ±2mm tolerance means the effective sensing distance varies between 7mm and 11mm across production variations in the sensor (manufacturing tolerances in the LED output and receiver sensitivity).

For installation, the sensor should be set at a physical distance from the substrate that remains within the functional range across this tolerance — typically at the nominal 9mm with the machine adjusted to maintain this gap against substrate wander and web tension variation. 

The analogue output level can be used to confirm that the sensor is within its effective range during setup.

Q4: Can the NT6-03022 detect a yellow mark on a white background — a notoriously difficult detection task?

This is exactly the detection task the 560nm dual-colour illumination is designed for.

Yellow and white differ in their spectral reflectivity most significantly in the green-to-red transition around 560nm — yellow absorbs blue and reflects strongly in the 560–620nm range, while white reflects all visible wavelengths uniformly.

The NT6's combined red/green illumination at the 560nm effective wavelength exploits this spectral difference to maximise the contrast signal between yellow and white, providing detection where a single-colour sensor at 660nm (red) or 880nm (infrared) would see minimal contrast.

Q5: Is the NT6-03022 suitable for clear/transparent label detection?

Transparent label detection is a specific application that requires a sensor designed for the very small contrast difference between a clear label on a clear liner and the liner alone. The NT6-03022, as a contrast sensor relying on colour-dependent reflectivity differences, is not optimised for clear label detection — the contrast difference at 560nm between a clear label and its liner is minimal.

For clear label detection, a dedicated ultrasonic or specialized through-beam sensor is the correct technology choice.