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Vertical Carousels at 60: Not Ready for Retirement

Sept. 7, 2012
Vertical carousels are not what they were 60 years ago. Today’s systems offer greater storage flexibility, safety advancements, security improvements and software integration.

The basic concept of a vertical carousel remains a reliable constant: a motor drives a number of chain-attached carriers around like a ferris wheel to deliver the desired product to the operator at an access opening. However, in 60 years many improvements have been made to improve efficiency and overall usability.

Efficiency and Usability

Today’s vertical carousel requires less energy to operate and has a lighter unit weight, while maintaining a higher MTBF (Mean Time Between Failure) rate than most household appliances. Most come standard with a hand crank, allowing 24-7 access to stored goods even without power.

A variety of carriers are available to provide storage flexibility. Standard shelf carriers can be sub divided to maximize storage density. Rollout drawers can be installed to hold small parts. Numerous specialty inserts can store anything from heavy tools and dies to sensitive electronic components. Carriers can be designed around the items being stored, and easily changed or modified in the future.

Safety and Security

Worker safety has improved. Vertical carousels come standard with safety lights located at pinch points. While the carousel is in motion, if the light barrier is interrupted the carousel automatically stops to prevent operator injury. Vertical carousels can also be equipped with multiple access openings allowing workers to store items using one access point and retrieve items from another access point. This allows items to be stored on one floor and retrieved on another floor without having to carry the items up stairs or to transport items using a cart or elevator.

Automated doors contribute to product security, allowing valuable products to be secured in the vertical carousel. The security doors remain closed while the carousel rotates to the desired location, preventing the operator from reaching in and accessing other stored items as they pass by the access opening. The automated security door only opens after the carousel has arrived at the desired carrier, allowing the operator access to only the stored items on that specific carrier.

Inventory management software provides traceability, enabling the storage and management of high dollar value items.

System Integration

Besides inventory tracking, the integration of inventory management software also allows features such as barcode scanning and pick-to-light technology. Inventory management software also provides dynamic space management to increase the storage density within the unit.

Pick-to-light technology has evolved from a single illuminated LED used to direct the operator to the item to be picked. Today’s vertical carousels offer complete message centers that direct the worker to the location of the item to be picked, display the part number or description, pinpoint the exact compartment and whether to pick or store, and what quantity.

Order Picking Vitality

The most overlooked application for a vertical carousel is order picking. When picking orders that average four lines per order or more, vertical carousels with inventory management software offer fast retrieval times, good throughput and minimal operator travel time.

Using inventory management software, a vertical carousel will only rotate around one time to make all picks required for an order. This means the time it takes to deliver a complete order to the operator will never be longer than the time it takes for a vertical carousel to make one full rotation. An average sized vertical carousel at 20 feet can make a complete rotation in 90 seconds compared to technologies where trays are extracted (it would take up to 132 seconds to deliver four trays to an operator).

Proper Slotting

If you slot the storage machine efficiently and two of the four parts are located on the same tray, the storage device only has to retrieve and deliver three trays, cutting the delivery time. The same argument can be made for the vertical carousel. When slotted properly, the most frequently picked items (or fast movers) are stored on carriers that are close to one another, cutting machine delivery time.

Vertical carousels can also be programmed with a “home” location. When the machine has sat idle for a specific amount of time and no order is currently being picked it automatically rotates to the home position. This ensures that when the next order is ready to be picked the vertical carousel is already rotated to the “home” position where fast movers are stored.

Batch Picking for Better Throughput

When integrated with software, batch order picking is possible. Batch order picking is the process of picking multiple orders (or a batch) at a time. A combination of vertical carousels, software, a batch station and pick to light technology allows an operator to batch pick. A batch station is commonly located in front of the carousels and the operator stands between the carousels and the batch station.

First, an operator assigns an order to a tote on the batch station. The software coordinates the picks so that the carousel rotates around to present the operator with the first pick and the lights direct the operator to pick a specific quantity of that SKU from the carousel. The operator picks the quantity and turns to distribute them among the batch of orders located on the batch station. This allows the operator to fill multiple orders with only one rotation of the vertical carousel, increasing throughput substantially.

Less Walk Time

When order picking, it’s always important to take into consideration operator walk time. A typical vertical carousel is 12 feet wide. Lining up four vertical carousels in a row, side by side, can create a 48 foot area for an operator to cover. Instead, place two vertical carousels next to each other and the other two vertical carousels across from the first two. The operator then only has to walk a maximum distance of 24 feet to make a pick. When designing a vertical carousel order picking system it is important to strategically place the carousels to minimize walk time.

Picking a Good Example

An electronic contract manufacturer based in Utah uses three 20-foot vertical carousels for order picking. The vertical carousels manage the electronic components used to produce printed circuit board assemblies. Orders are picked daily to feed the manufacturing line. The vertical carousels have pick-to-light technology and are equipped with inventory management software that interfaces with the user’s ERP system.

When a job is ready for fulfillment, the order is downloaded from the ERP system to the vertical carousel’s inventory management software. When ready, the operator starts the order, causing the vertical carousels to spin into position for picking and the batch lights to light. The operator moves from one pick to another filling the job order. Most job orders contain between 100 and 150 lines.

The carousels require fewer people and allow the company to fill job orders faster. Previously picking orders from shelving, the company has seen not only improved productivity, but an uptick in picking accuracy as well.

Christina Dube is marketing communications manager at Kardex Remstar, LLC (

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