Visolux-Hotoelektrischer Sensor ML4-8-KSU-1062/25/32/71

ML4-8-KSU-1062/25/32/71（Visolux / Pepperl+Fuchs Hintergrundunterdrückung Fotoelektrischer Sensor）

Visolux is the original brand, later acquired by Pepperl+Fuchs. The complete model is often suffixed with B: ML4-8-KSU-1062/25/32/71B, commonly known as the Eye Spot Assembly small-spot photoelectric eye. It is an obsolete discontinued model.

Aufschlüsselung des Modellcodes

`ML4-8-KSU-1062/25/32/71`

1. ML4-8: ML4 series compact square photoelectric head, 8 mm mounting hole specification, Art der Hintergrundunterdrückung (BGS)
2. KSU: Circuit/output configuration code, fixed cable with M8 connector, red light spot, non-adjustable version
3. 1062: Internal revision / optical component code
4. 25: Code related to sensing distance
5. 32: Ausgabetyp (Gleichstrom, Schaltausgang)
6. 71: Gehäuse, cable length and mounting bracket configuration code

Core Technical Summary

Prinzip: Hintergrundunterdrückung (BGS). It suppresses interference from background objects behind the target, suitable for detecting tiny workpieces at short range.

Lichtquelle: Modulated red light, small light spot, designed for micro-point detection (Drucken, label marking, material edge detection, web registration).

Konstruktion: Integrated photoelectric head, factory-fitted fixed cable with M8 circular connector and metal mounting bracket.

Status: Permanently discontinued by manufacturer. Only used or reconditioned units available on the market; no brand-new original stock.

Equivalent active replacement (Pepperl+Fuchs): ML4.2-8-H series, z.B. ML4.2-8-H-20-RT/40b/95/110. Also small-spot BGS with highly compatible mounting hole layout.

Typische Anwendungsszenarien

Druckmaschinen & label machines: Mark/color mark detection

Verpackung & web production lines: Edge registration, presence detection of tiny materials

Textil & paper machinery: Point registration / background detection

Wartung & Beschaffungshinweise

1. Alternate part number: `3052370141` (material code used in some system databases)
2. Common failures of used units: Degraded red LED light spot, broken cable at cable root, oxidized pins on M8 connector
3. Replacement precautions: Verify spot size, switching frequency, output polarity (NPN/PNP) and supply voltage. The output logic of the old KSU version differs from the newer ML4.2 series; perform testing before commissioning.

Application Scenarios of Background Suppression Photoelectric Sensors (BGS)

Kernvorteil: Based on triangulation principle. Only objects within the set distance window are detected; background objects (metal frames, Förderbänder, walls) further away are automatically suppressed. Performance is largely independent of workpiece color and reflectivity. The ML4-8-KSU above is a small-spot BGS optimized for micro-point detection.

1. Verpackung & Druckindustrie (Primary use for ML4 series)
2. Color mark detection & web edge registration: Labelers, flexo presses, Schneidemaschinen. Detects printed marks and film edges, immune to reflection from metal rollers behind the web.
3. Cap / seal inspection: Verify cap presence and crimping completeness against stainless steel rotary table backgrounds.
4. Karton / pouch counting on conveyors: Detect cartons on conveyor lines with metal frames behind; standard diffuse sensors suffer frequent false triggering.
5. Label presence inspection: Confirm whether labels are applied, distinguishing labels from substrate base color.
6. Materialhandhabung & Logistik
7. Werkstück / parcel presence detection on belt conveyors, trigger signals at sorting chutes
8. Palletizing / depalletizing machines: Cargo detection on pallets; the pallet itself does not cause false activation
9. AGV material level sensing, bin occupancy detection
10. Small part counting, separating workpieces from background conveyor frame

III. 3C Elektronik & Precision Custom Automation

1. Presence detection of PCBs, connectors and small plastic parts
2. End-of-arm workpiece detection on robot grippers; metal gripper housings do not generate false signals
3. Inspection of thin sheets, springs and micro-components (small-spot BGS is preferred for applications like the ML4 series)
4. Lithium battery production lines: Cell and electrode sheet detection, handles highly reflective blue aluminum surfaces
5. Automobilbau
6. Fit-check detection of body components: Plastic parts, Gummiteile, stamped metal parts
7. Part presence check inside tooling fixtures; suppress reflection from metal fixture backgrounds
8. Position trigger for workpieces on sliding conveyors
9. Essen & Getränkeindustrie
10. Bottle and can detection against stainless steel conveyor surfaces
11. Content detection inside packaging bags, distinguishing packages from metal machine frames

IP67-rated versions are available to withstand washdown environments

1. Textil & Papierindustrie
2. Leading-edge detection for fabric and paper webs, fabric edge sensing, unaffected by background rollers
3. Paper break monitoring

✅ Selection Guidance: When to choose BGS (Hintergrundunterdrückung)

Target is positioned in front of metal, high-reflective, light/dark fixed background, and standard diffuse sensors trigger falsely

Stable detection is required for both black low-reflective parts and white high-reflective parts

Fixed sensing distance required, objects outside the detection window must not produce signals

Tiny workpieces, narrow edges or mark point detection (small-spot models such as ML4 series)

❌ Not Recommended Use Cases

Long-range detection (>1 M): Prefer standard diffuse sensors or laser distance sensors

Transparent films / transparent bottles: BGS has poor performance on transparent targets; through-beam photoelectric sensors are preferred

Large thickness variation of target parts within sensing window where parts may cross the detection boundary

Replacement Options for Obsolete Visolux ML4-8-KSU

Originalmodell: ML4-8-KSU-1062/25/32/71B, eingestellt. Small-spot red-light BGS for color mark and web registration on printing/label machines. Supplied with fixed cable, M8 connector and metal mounting bracket.

✅ Primary Same-brand Direct Replacement (Active Pepperl+Fuchs ML4.2 series, kompatible Befestigungslöcher)

ML4.2-8-H-40-RT/40b/95/102 (Top-Empfehlung)

Prinzip: Triangulation background suppression, modulated red light, small light spot, optical characteristics closest to legacy ML4

Erfassungsbereich: 10~40 mm (matches 25 mm rated sensing distance of original unit)

Spot diameter: Ca. 3 mm at 40 mm, ideal for micro-mark and web edge detection

Stromversorgung: 10~30 VDC, NPN-Ausgang, reinforced metal 8 mm mounting hole

Merkmale: Non-adjustable version, consistent with legacy KSU, tamper-proof, suitable for retrofitting printing, flexo and slitting machines

Order part number: 34475

Alternative within the same series: ML4.2-8-H-20-RT/40b/95/110, 20 mm sensing range with smaller spot, preferred for close-range point detection.

📌 Other Pepperl+Fuchs Alternatives (Gleiche Marke, Similar Form Factor)

1. ML100-8-H-100-RT/102/115: ML100 series, longer sensing range (5–100 mm), slightly larger spot. Select when extra sensing distance is needed and space permits; mounting holes compatible.
2. OBT40-R102-A0-V31: New compact BGS with IO-Link for parameter configuration and remote monitoring. For new projects requiring diagnostics; different body dimensions, mounting bracket modification required.

🧩 Cross-brand Compatible Alternatives (KRANK, same-spec small-spot BGS widely used in printing)

WTB4-3P2161: Small-spot background suppression, Rotlicht, 0–40 mm sensing range, M8-Stecker, square housing. Widely deployed on printing machinery for drop-in replacement; verify NPN/PNP.

WTB8-2P1311: Short-range small-spot BGS with high resistance to reflective backgrounds, suited for web edge registration.

⚠️ Critical Verification Points Before Retrofit (Mandatory for Legacy Machine Upgrade)

1. Spot Size: Original ML4-8-KSU has an ultra-fine spot. Do not use standard BGS with large spot; otherwise false triggers occur during color mark / edge detection.
2. Output Polarity: Output logic differs between legacy KSU and ML4.2. Confirm Light-ON (L.O.) / Dunkel-EIN (D.O.) before power-up.
3. Verkabelungsdefinition: M8 pin assignment differs between old and new sensors. Never direct hardwiring without verification to avoid burning the sensor.
4. Montagehalterung: Legacy unit comes with dedicated L-shaped metal bracket. ML4.2 body shares identical hole spacing, but original bracket is not interchangeable; new bracket procurement or machining required.
5. Antworthäufigkeit: For high-speed web printing, response speed must match original sensor to avoid missed signals at high line speed.

❗ Procurement Backup Plan

The legacy ML4 model is permanently discontinued by manufacturer. Only used/refurbished stock available. Risks of second-hand units: Red LED aging, spot attenuation, cable root fracture, connector pin oxidation. Only acceptable for emergency temporary repair.