Put-to-Light Systems

The primary advantage of put-to-light systems is dramatic improvement in sorting accuracy. By providing clear visual guidance for every put action, these systems virtually eliminate the sorting errors that commonly occur with manual label reading or memory-based sorting. Accuracy rates typically exceed 99.9%, significantly reducing costly mis-shipments and customer complaints.

Productivity gains are substantial, with put-to-light systems enabling workers to process 300-600 lines per hour compared to 100-200 lines per hour with manual sorting methods. The intuitive visual interface requires minimal training, allowing new workers to achieve high performance levels within hours rather than days or weeks.

The technology also delivers ergonomic benefits by eliminating the need for workers to repeatedly read small labels or reference paper pick lists. The large, bright displays reduce eye strain and allow workers to maintain better posture during sorting operations, contributing to reduced fatigue and fewer workplace injuries.

Flexibility is another key advantage, as put-to-light systems can easily adapt to changing order volumes and profiles. Stations can be reconfigured to handle different numbers of orders, and the system automatically adjusts to accommodate varying order sizes and complexities without requiring physical changes to the infrastructure.

A complete put-to-light system consists of several integrated components. Light modules mounted at each order location feature LED displays, confirmation buttons, and sometimes alphanumeric displays for showing additional information like order numbers or special instructions. These modules connect to a central controller via wired or wireless networks.

Barcode scanners or RFID readers identify items as they arrive at the sorting station, triggering the appropriate light displays. Many operations use hands-free ring scanners or wearable devices to maximize worker efficiency and maintain ergonomic working positions.

The control system manages communication between light modules, scanning devices, and the WMS, ensuring real-time synchronization and accurate order tracking. This system also provides performance monitoring, error detection, and diagnostic capabilities to maintain optimal operation.

Order containers or totes are positioned beneath or adjacent to each light module, creating clear associations between displays and destinations. Container designs vary from simple cardboard boxes to sophisticated flow racks that automatically advance completed orders to packing stations.

Successful put-to-light implementations require careful planning and design. Station layout should minimize worker movement while providing clear sight lines to all light displays. Most operations arrange containers in a U-shape or straight line configuration, with the worker positioned to reach all locations comfortably without excessive stretching or twisting.

Batch sizing must be optimized to match station capacity and order profiles. Stations typically handle 8-48 orders simultaneously, with the optimal number depending on factors like average items per order, item size, and worker capability. Larger stations increase efficiency but may overwhelm workers or create ergonomic challenges.

Wave planning coordinates the release of batches to put-to-light stations, ensuring steady workflow without creating bottlenecks. The WMS should group orders intelligently, considering factors like shipping deadlines, carrier schedules, and order characteristics to maximize station utilization.

Quality control processes should be integrated into the put-to-light workflow, with systems configured to flag exceptions like short picks, damaged items, or quantity discrepancies. Many operations implement verification scans at the packing stage to catch any errors before shipment.

To maximize put-to-light effectiveness, consider these proven strategies. Dynamic order assignment allows the system to continuously optimize which orders are assigned to each station based on real-time conditions, item availability, and worker performance. This flexibility prevents idle time and ensures balanced workload distribution.

Multi-level sorting uses put-to-light for initial distribution followed by secondary sorting for orders requiring items from multiple batches. This approach works well in operations with complex order profiles or when order volumes exceed single-station capacity.

Performance monitoring at both the worker and system level helps identify training needs, process bottlenecks, and opportunities for improvement. Track metrics like puts per hour, error rates, and station utilization to understand where the operation excels and where it needs attention.

Maintenance protocols should include regular cleaning of light modules, testing of confirmation buttons, and verification of scanner accuracy. Preventive maintenance prevents unexpected downtime and ensures consistent performance.

Put-to-light systems work exceptionally well with batch picking strategies, where workers collect items for multiple orders in a single trip through the warehouse. The put-to-light station becomes the consolidation point where batch-picked items are efficiently sorted into individual orders.

Zone-batch picking operations often use multiple put-to-light stations, with each station handling orders that have completed picking in all required zones. This approach enables high-volume operations to process thousands of orders daily while maintaining accuracy and efficiency.

Some operations combine put-to-light with goods-to-person systems, where automated storage and retrieval systems deliver items to put-to-light stations. This integration creates a highly efficient, largely automated fulfillment process that minimizes labor requirements while maximizing throughput.

Several variations of put-to-light technology address specific operational needs. Put-to-store systems guide workers in sorting items for retail store replenishment, with each light location representing a different store. This application is common in retail distribution centers preparing store-specific shipments.

Put-wall systems arrange light modules vertically on walls or racks, maximizing the number of order locations in limited floor space. These configurations work well for small-item fulfillment where order containers can be compact.

Mobile put-to-light solutions use carts equipped with light modules, allowing workers to perform sorting operations at different locations within the warehouse. This flexibility is valuable in operations with variable workflows or limited dedicated sorting space.

Key performance indicators for put-to-light systems include puts per hour per worker, sorting accuracy rates, order cycle time from batch arrival to sort completion, and station utilization. These metrics help assess system effectiveness and identify optimization opportunities.

Error rates should be tracked by error type—wrong location, wrong quantity, missed items—to understand where additional training or process improvements are needed. Most operations target error rates below 0.1% for put-to-light operations.

Return on investment typically materializes within 12-24 months through labor savings, reduced error costs, and increased throughput capacity. The combination of higher productivity and improved accuracy creates compelling economics for operations processing significant order volumes.

By implementing put-to-light technology with careful attention to station design, workflow integration, and performance monitoring, warehouses can transform their sorting operations from error-prone bottlenecks into efficient, accurate processes that support rapid order fulfillment and customer satisfaction.