Maximizing Efficiency with Mixed-Case Palletizing

Many high-throughput distribution centers face a growing logistics challenge — the need to prepare a wider variety of orders to ship and arrive on schedule and with a near-zero tolerance of errors. Sometimes comprising thousands or tens-of-thousands of different SKUs and in an assortment of package styles, these items need to be stored, picked and stacked on pallets or roll cages ready for outbound transport with a very high level of efficiency to optimize labor usage and minimize operational costs. The product styles include boxes of all sizes, cans and jars in cardboard trays, open and closed cartons, beverages, bags and large, unstable tissue packages.

The number of different SKUs with their varied packaging is growing continually and becoming increasingly difficult to handle with manual and conventional automated systems. Distribution centers (DCs) are also experiencing a growing need to deliver these orders in more store-friendly formats to a diverse and expanding range of store configurations, yet within an environment of rising DC labor costs and stricter safety regulations.

One area of the DC supply chain that has recently experienced a quantum leap in efficiency is automated palletizing for handling a high volume of mixed-SKU cases. By using sophisticated software and articulated, servo-driven robots that receive product in an automated sequence — when functioning as a sub-unit of a larger automated order assembly system — these automated palletizers are capable of rapidly building cube-optimized, virtually error-free, store-ready/aisle-ready pallets.

Evolution in Palletizing

As early as the 1950s, conventional automated palletizers, which could process a single SKU continuously, came into use. By the late 1970s, robotics began to be employed to increase the flexibility of automated systems for singular SKU counts and different palletizing configurations. However, the cycle time was limited due to robot performance. With the introduction of servo-motors in the late 1980s, the speed and performance of single-SKU palletizing systems advanced considerably.

By the late 1990s, with the addition of improved software, mixed SKU palletizing systems — able to handle 350 to 400 SKU counts with limited package variety — began to appear in DCs. Equipped with articulated robots, these systems have proven valuable for DC operations, such as beverage distributors, with a typical low-SKU-count product range.

The first versions of automated high-SKU, mixed-case palletizers became available to the logistics market around 2005. Equipped with four-, five- and six-axis robots and software with expanded capability, these highly-automated systems have begun a new evolution in volume-SKU, mixed-case palletizing.

Now, the latest generation of these systems provides greatly improved software and more versatile product gripping tools, capable of building a higher, more dense and more stable pallet than prior systems, with improvements in system speed, order accuracy and store-friendly flexibility. The latest of these automated, high-volume, mixed-case systems can access tens-of-thousands of SKUs and palletize more than 1,000 mixed cases per hour, averaging 130 different SKUs per pallet (1.2 cases of a particular SKU per pallet).

High-Rate Palletizing

To process and palletize mixed cases at high-speed rates with such high accuracy, product needs to be fed into the system in a sequenced format. This requires supporting an integrated automation upstream solution, consisting of delayering incoming single-SKU pallets, storage, picking and case buffering. The latest mixed-case palletizing units integrate with both high-speed, automated storage and retrieval systems (AS/RS) and conventional pallet racking.

One example of the new high-SKU systems is AMCAP, an automated, mixed-case palletizing system from Dematic Corp., a supplier of logistics automation solutions, systems and service. While referencing some specific capabilities of the Dematic system, this article will illustrate the type of performance improvements available to material handling professionals using any high-rate, mixed-case palletizer.