In recent years the increase in time-based competition and the growth of e-commerce have put pressure on logistics managers to reduce the cost of DC design and management activities. This importance and interest in DC system design is justified by the behavior of strongly changing global and extended markets which require companies to process and manage increasingly differentiated products with shorter life cycles, low volumes and ever shorter customer delivery times.

Nevertheless, companies attempt to achieve high volume production and distribution using minimal inventories throughout the logistic supply chain in accordance with shorter response time.

Now, with a decade of growth in e-commerce, and the strength of its development, there is a renewed focus on DC activities and facilities, in particular on the management of order picking systems which are being required to process a far higher volume of smaller orders resulting in escalating picking costs.

In most DCs, the typical manual discrete order picking process is to travel through the facility and build an order. This picking method is referred to as “Picker-to-Product”. In a full case batch order picking system, pickers may have to cycle through the entire pick module for each batch of orders. As orders and batches become smaller these methods become less efficient.

However, retailers and some wholesalers are good candidates for the adoption of an alternative “Product-to-Picker” (or more simply “put”) order fulfillment configuration since in these operations many of the same SKUs are being ordered across a majority of the stores/customers.

In a typical “put” system containers of individual SKUs are delivered to an order fulfillment zone where an operator is stationed. Each zone is equipped to serve several different store/customer orders. Instead of picking SKUs while moving pass them, SKUs are allocated (put) to the orders that require them. The operator “puts” the required quantity of the product into customer specific, bar coded, shipping cartons that will (when full or completed) go to the retail store, industrial user or consumer. RF scanning, Put-to-Light, and Voice Directed technologies, or some Multi-Modal combination thereof, can be used to direct the operator and to insure inventory and order fulfillment accuracy.

Delivery schedules may range from daily, to every other day, or whatever is required for that particular store/customer.

Key industries ideal for Product-to-Picker systems include:

• Retail/Wholesale
• Pharmaceutical
• Apparel & Accessories
• Music, Book & Media Publishing/Distribution
• Electronics
• Cosmetics & Beauty Products
• Vitamins

The Simplicity of Put Systems Yield Many Benefits

For those operations that are required to ship product to the same locations on a recurring basis, put systems may offer a greater range of process control, increased order fulfillment efficiency and improved access to operator metrics. Additional benefits often include reduced space requirements, controlled access to product and improved accuracy.

However, the major benefits associated with typical Product-to-Picker systems are reduced operator travel and elimination of the dedicated pick face. In a put configuration, all required SKUs are brought to the operator; therefore, the order fulfillment staff does not need to travel throughout the facility. Further, by eliminating the dedicated pick face there is no need for slotting and re-slotting.

Pick rates for put systems are typically higher than conventional “Picker-to-Product” systems configuration where there is a pick face for every SKU. Ken Ruehrdanz, Market Development Manager for Dematic (www.kenneth.ruehrdanz@dematic.com), has been quoted as saying – “Systems that migrated to put order fulfillment can increase picking rates from 1.5 to 3 times depending on the system configuration”.

In an article Ruehrdanz wrote last year he provided the following three examples of put systems:

• A general merchandise retailer redesigned its operation to incorporate put order fulfillment. With 125 stores, there is one pallet position dedicated to each store. A pallet of one SKU is moved on a pallet jack to the store pallet locations. Stores that require this SKU receive the required number of cases. Put instructions are provided to the operator with a wearable voice device. Pick rated in this application improved from 70 cartons per hour per picker to 122, while providing real time tracking of product.

• An Internet retailer used a high density staging device to store thousands of SKUs instead of providing dedicated pick faces. Multiple operator put stations are connected to the storage system with a conveyor network. SKUs required to fill orders are delivered to the put stations where operators put the items into a shipping container. When the single or multi-line orders are completed, the conveyor network takes the carton to shipping. In this configuration, put operators obtain 250 lines per operator per hour, a two-fold increase when compared to the previous system. Other benefits include reduced warehouse space requirements, controlled access to product and improved accuracy.

• An apparel retailer used a zone put system. There are 20 put zones in the system; there are 1,000 stores and 50 store carton positions per zone. One operator works in a zone. Cartons containing one SKU are removed from storage and routed to put zones that require the SKU. A carton of one SKU travels only to the zones where the store has ordered that SKU. The zone put system enables 325 puts per operator per hour.

Light-Directed Put Sortation

Put-to-light and pack-to-light are variations of Product-to-Picker order fulfillment systems. Put-to-light commonly refers to the distribution of a product across multiple locations, where each location contains a container or tote that is associated to an order. Pack-to-light is more specific because it implies that the location holds the shipping container that is delivered to the store/customer.

Batch picked items are directed to a consolidation/sort area, which employs a put-to-light system. Here item quantities are distributed across multiple positions; following the display unit “put to” instructions, thus building discrete orders in their respective put-to or pack-to locations.

There are several well established mechanized Product-to-Picker technologies that are available such as horizontal carousels, vertical carousels, and mini-load automated storage and retrieval systems, which can virtually eliminate all picker travel time.

The Future for Put Systems Looks Good

As described in the SCDigest report (“Automated Case Picking 2009: The Next Frontier in Distribution Management”), a new generation of AGVs has come to market with flexibility improvements that make them much more suitable for DC deployment (working alongside workers on the floor), including case (and piece) order picking as well as basic transport functions. These advances include much more sophisticated controls, allowing flexible and dynamic movement paths, and in some cases “optical” guidance systems that enhance flexibility and safety.

This new class of automation really should be considered a more “mobile robot” than AGV, though they share a heritage. For more details on how AGVs are being deployed in Product-to-Picker systems see page 20 of the above reference report.

Final Thoughts

While Picker-to-Product systems such as batch order picking with associated order consolidation sorting continue to offer excellent benefits for many general merchandise distributors, alternative configurations that bring products to the picker can provide enhanced benefits for specific operations. It does not have to be an either or situation. Deploying a combination of these methods may be the key strategy to obtaining the lowest overall operating cost.

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