Case Study

Sensorless muting light curtains eliminated conveyor downtime at a Fortune 50 distribution center.

Industry: Consumer Goods

A Fortune 50 consumer goods distribution center in the Midwest was struggling with recurring conveyor downtime on its outbound packaging line. The cause was not equipment failure. It was false trips in the safety light curtain muting system. The culprit was conventional muting sensors that could not distinguish between actual safety hazards and the routine realities of high-volume pallet movement: stretch-wrap film tails extending past the pallet edge, partially loose barcode labels, and vibration-induced sensor misalignment. Every false trigger meant a manual reset, lost throughput, and mounting operator frustration. It became the customer’s single most frequent fault on the outbound line.

Han-Tek partnered with Leuze to replace the traditional muting setup with Leuze’s patented MLC 530 SPG-RR sensorless muting light curtains, then integrated them into the conveyor system’s PLC logic. The result: nuisance stops eliminated, system availability above 99.5%, and the customer standardized on the same technology for every future expansion.

Their Challenge:

False trips from safety light curtain muting systems were interrupting the outbound packaging zone on a daily basis, generating the single most frequent fault on the line.
Stretch-wrap film tails extending beyond pallet edges were the primary trigger of nuisance faults, a normal byproduct of standard wrapping operations on every outbound pallet.
Partially loose barcode labels protruding from pallet edges were also causing false stops, with no clean way for traditional muting sensors to filter them out.
Vibration-induced misalignment of conventional external muting sensors compounded the problem over time, adding maintenance and calibration overhead to the daily nuisance stops.
Each false trigger required manual operator intervention and a full system reset, eroding throughput, slowing the loading bay, and pulling staff away from other line duties on every shift.

Our Solution:

Han-Tek partnered with Leuze to deploy Leuze’s patented MLC 530 SPG-RR sensorless muting light curtains, replacing the traditional external-sensor muting setup. The SPG-RR (Smart Process Gating with Reduced Resolution) variant is engineered specifically to filter out transient signals from stretch-wrap film, separator papers, and cardboard flaps without compromising genuine safety detection.
The system uses a two-signal architecture engineered into the conveyor controls: the PLC sends a Control Signal (CS) when transport material approaches the safety field, and the light curtain generates a Protective Field Interruption (PFI) signal automatically when it detects the object. The combination allows controlled, sensorless passage of pallets through the protective field while still detecting and stopping any unsafe personnel entry.
The system carries Type 4 / PL e / SIL 3 certified safety performance, TUV certified, with no compromise on safety integrity compared to the previous external-sensor muting setup.
Because the SPG architecture operates without external muting sensors or brackets, Han-Tek eliminated the sensor alignment issues, vibration-induced false trips, and additional footprint that came with the previous configuration. The installation envelope shrank and wiring complexity dropped.
Han-Tek integrated the SPG light curtains directly into the conveyor system’s PLC logic as part of the customer’s broader integrated conveyor system, keeping the controls architecture clean and maintaining full safety compliance across the line.
Leuze application engineers collaborated with Han-Tek and validated the solution on-site, combining innovative safety technology with system-integration expertise to deliver measurable production gains.

The Results:

Metric	Before (Traditional Muting)	After (Leuze SPG-RR)
Nuisance stops	Frequent (daily)	Eliminated
Downtime	High	Negligible
Operator intervention	Regular	None required
System availability	Inconsistent	Greater than 99.5%

- The customer’s #1 most frequent fault was eliminated: Daily nuisance stops caused by stretch-wrap tails went from being the single most common fault on the outbound line to being completely eliminated.
- System availability over 99.5%: Uptime on the outbound packaging line jumped from inconsistent to consistently above 99.5%, with no operator resets required to maintain the rate.
- Standardized for future expansions: The facility standardized on the Leuze SPG light curtain for all future expansion equipment and shared the results internally with other company sites.
- Maintenance burden reduced: No sensor realignment or calibration is required on the SPG architecture, eliminating the routine maintenance the previous external-sensor setup demanded.

“The new light curtains have completely changed the performance of our outbound loading. We’ve eliminated all the nuisance errors. We’ll be installing these on the expansion equipment and sharing the results with other company sites. Great improvement!”
Facility Representative

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