Mixed case palletising solutions

David Rubie, Industry Logistics Manager, Dematic

Driven by OHS concerns and skills shortages, there is an increasing demand for smart solutions that take mixed case palletising in a new and exciting direction. Advances in software, robotics and intelligent storage, buffering and sequencing systems have enabled the development of two innovations designed to reduce the cost and improve the efficiency, productivity and safety of building mixed case pallets.

Until recently, the only way to assemble a pallet containing many different SKUs (stock keeping units) was to do it manually. But repetitive and heavy tasks are both physically demanding and costly. And, unless mixed case pallets are carefully assembled, the resulting stacks of goods may be unstable, risking product damage during transport and adding to transport costs by taking up more space than necessary.

To provide high-volume distributors with smarter, safer, more cost-efficient alternatives to manual mixed case palletising, Dematic has developed two solutions - ErgoPall Ergonomic High Rate Palletising Stations and AMCAP (automated mixed case palletising).

Both systems employ a combination of automated storage, buffering and sequencing systems, advanced software and automated materials handling equipment, the main difference being that ErgoPall still uses people to build the pallets - but in an ergonomic way - while AMCAP uses sophisticated robotic palletisers.

Facilitating high-rate, mixed-case palletising

In order to process and palletise mixed cases accurately at high speeds, products need to be fed into the system in the correct sequence to suit pallet assembly.

Key to the development of the ErgoPall and AMCAP solutions was the evolution of smart, product storage, buffering and sequencing systems including Dematic’s Miniload and Multishuttle automated storage and retrieval systems (ASRS).

Manual mixed case order assembly, in particular, can be done more safely and with much greater efficiency, accuracy and productivity when goods are presented for palletising in the correct sequence.

How high-rate, mixed-case palletising works

The distribution centre’s warehouse management system (WMS) interfaces with Dematic’s WCS (warehouse control system), which controls all aspects of the order assembly process including pallet breakdown or delayering, storage, buffering, picking, sequencing, transport and palletising.

When the WMS releases orders, the WCS sorts the data and sends the pallet stock information to Dematic’s PalletGenDirector software. PalletGenDirector uses different attributes of the product (length, width, height, weight, etc) and stacking criteria factors including crushability, stability factors, volume of cases per layer, number of layers, the layer pattern, and family group rules unique to stores, departments, aisles and aisle sections to determine the optimum build sequence for each pallet.

Pallets of stock for the orders are then automatically delayered or manually broken down and conveyed to the high-speed Miniload or Multishuttle storage buffer and sequencing system. When required for an order, the necessary SKUs are automatically picked and transported in the exact sequence required to facilitate pallet assembly.

The computer-aided determination of the palletising build sequence increases pallet density, typically building cube and volume-optimised pallets with a density of 90%+ compared to the 70 to 80% density of conventionally hand-stacked pallets.

Ergonomic, high-rate palletising stations

ErgoPall Ergonomic High Rate Palletising Stations enable operators (one or two per station depending on the application) to ergonomically build mixed SKU pallets.

The ErgoPall stations are built on a mezzanine with integrated conveyors delivering a constant flow of mixed cases to the operator, enabling the operator(s) to simply slide the sequenced cases into position on the pallet.

Lifting is virtually eliminated and, as each layer of cases is completed, the pallet automatically lowers, enabling assembly of the next layer to begin, significantly reducing the physical effort required and improving the safety, speed and quality of order assembly.

As the pallet is being lowered, it is stretch wrapped for stability. When all of the goods required for an order have been placed on the pallet and the stretch wrapping completed, the pallet has a label applied to it as it exits the system on an outbound conveyor.

Palletising, however, continues even while the built pallet is being removed from the ErgoPall station, with only a few seconds lost in the transition. After the pallet continues down through the mezzanine, slider plates close above it to form a solid surface upon which the ErgoPall station operator(s) can immediately begin stacking cases for the next pallet to be built. Concurrently, a new empty pallet is raised by the lift to the underside of the slider plates, which open gently transferring the already picked cases to the surface of the new pallet, as the operator(s) continue assembling the order.

Dematic is currently installing 16 ErgoPall stations as part of a sophisticated order assembly system for Danish supermarket giant Dansk Supermarked Gruppen (DSG).

Requiring just 28 operators, the order assembly system will build 250 mixed case pallets per hour, producing compact store-friendly pallets to suit the retailer’s multiple store formats.

DSG’s large SKU range of more than 17,000 products adds to the complexity of the order assembly challenge with up to 100 different products needing to be consolidated on the one pallet in a store-friendly sequence specific to each store and department’s requirements.

Automated mixed-case palletising

Automated palletising is a very efficient solution to building pallets in high-volume distribution applications. However, until recently, automated palletisers have only been capable of handling a limited range of SKUs and packaging types.

Now advances in software, product storage, buffering, sequencing and recognition systems, and high-speed articulated robots with more versatile product gripping tools, have enabled the development of automated palletising systems capable of handling a diverse range of SKUs and packaging types including boxes of various sizes, cardboard trays, open or closed cartons, bagged goods and sacks.

Capable of building a higher, more dense and more stable pallet, with improvements in system speed, order accuracy and store-friendly flexibility, these extremely accurate, fast and reliable automated systems can handle tens of thousands of SKUs.

Optimised efficiency in the work cell

Each AMCAP cell comprises two six-axis, servo-driven articulated arm robots installed on a mezzanine. Two conveyors automatically deliver the SKUs to the work cell, at which point they are aligned, oriented and presented to the robots for pick-up, with the two robots building each pallet cooperatively. The combined dual-robotic cycle of feeding, grabbing and placing the SKUs enables the system’s high throughput rate of greater than 1000 mixed SKU cases per hour.

One of the unique aspects of AMCAP is the multi-axis, end-of-arm-tool (EOAT) attached to the robots’ articulated arms. This universal tool can handle all standard types of packaging without stopping or changing tools. There is no use of pneumatic suction technology, enabling it to grip virtually any type of packaging without product damage.

As per the ErgoPall solution, once stacking is complete, the pallet is automatically lowered through the mezzanine floor by an integrated lift, stretch wrapped, labelled and exits the system, with only a few seconds lost in the transition from one order to the next.

With the emergence of high-rate, mixed case palletising, a new level of flexibility, efficiency and safety above and beyond the capabilities of conventional automated and manual palletising systems has been realised. Improved productivity at both the DC and the store, the ability to deliver to multiple store formats, increased accuracy, reduced labour and optimised transport costs are just some of the benefits the systems can deliver.

By David Rubie, Industry Logistics Manager, Dematic