There are many different ways to store and manage inventory for internal or external distribution. Some of these methods, such as static shelving, are relatively low-tech. Others are more sophisticated, involving integrated computer applications and sometimes, robotics.
This second group includes a variety of automated storage solutions—not only horizontal carousels, but also vertical carousels, vertical lift modules (VLMs), ASRS or shuttle systems, and grid systems.
Static shelving is one of the most commonly used methods of inventory storage and management. Its big advantage is the low initial cost. However, because the dimensions of static shelving units are fixed, they cannot be adjusted to optimize warehouse space. In addition, when inventory is stored on shelves, pickers have to walk up and down the aisles of the warehouse every time they need to fill an order. That takes time, is error-prone, and can be hard on pickers physically (with all the “pounding the pavement,” bending, and repetitive motion). Static shelving can also introduce safety hazards. After all, an operator can only pick as high as they can see—beyond that, they have to reach or use a ladder. Reaching and climbing ladders create risks, and both add even more time to the pick.
Vertical carousels are automated storage solutions that operate on the vertical axis. The mechanism that drives a vertical carousel is similar to the mechanism that drives a Ferris wheel; however, rather than rotating on a circular path, as a Ferris wheel would, the shelving units move up and down vertically, following an elongated oval path. This configuration means that vertical carousels have a small footprint on the warehouse floor and can more than double the storage capacity of ordinary static shelving units.
What we call “the footprint” is measured at the base of the unit. Typically, a vertical carousel is five to seven feet deep and 10 to 12 feet wide—although at SencorpWhite, we can customize solutions to fit smaller niche spaces. When we are working with you to design a vertical carousel, we look at the square footage you currently are using for storage space and use that to help determine the pan depth, width, and height. The height can be variable, so if you are storing small items, we can make the shelves denser, and if you have tall items, we can make the shelves farther apart. This allows us to maximize storage density and minimize the footprint. Remember, usable storage is what fits on the shelves or in the pans. SencorpWhite has one of the smallest motor footprints in the industry, so the usable storage density is very near the overall cubic footprint.
Vertical carousels are becoming increasingly common across all sectors, in industries ranging from aerospace and manufacturing to retail and pharmaceuticals. That’s because in addition to increasing storage density, they can significantly improve warehouse performance. As with a horizontal carousel, a vertical carousel’s internal mechanism is integrated with computer software, creating a true “goods-to-person” delivery system. When a certain product needs to be picked, it is the software that directs the carousel to present the correct tote to the operator at the work counter. This accelerates pick speed, improves picking accuracy, and enhances workplace ergonomics.
Another advantage of SencorpWhite vertical carousels is that they include an emergency hand-crank for manual backup. If there is a system failure, operators can release the brake and use the hand crank to turn the internal mechanism. They can empty or fill the whole device, enabling operations to continue until the unit is running fully automated again.
Vertical lift modules
Vertical lift modules (VLMs) are similar to vertical carousels in that they run vertically and present trays to an operator. The operator can look across the tray, pick the item needed, and then press a complete button so that tray is removed and the next one is delivered. VLMs typically have a greater weight capacity than vertical carousels, which makes them ideal for heavier items. Another advantage to SencorpWhite’s VLMs is that they are available in single column or multiple column formats. In fact, one SencorpWhite VLM can provide up to seven windows to pick from. In some instances, there are windows on the front and windows in the back, so that picking and replenishment can happen simultaneously.
Both vertical carousels and VLMs offer dynamic shelving and light-directed picking. When a tray is presented to the operator, a shutter comes down across the back. An image of the product is displayed on the shutter, along with where it’s located on the tray and other information, including SKUs, quantities needed, and updated inventory counts. On vertical carousels, all of this can be displayed on the marquee bar that’s in front of the operator.
Some automated storage and retrieval systems (AS/RS) use a shuttle, similar to an unmanned fork truck, to run back and forth between static shelving units. The shuttle is able to move vertically and horizontally, and it can be programmed to travel to a shelf and retrieve items. Generally, shuttle systems are used for internal or external distribution of full pallets or cases and for heavy items, such as motors or other parts needed in assembly processes.
Grid systems fit all of the inventory into totes within a standard, closed unit box. Then, a robot is programmed to pick the items that are needed. The key with a grid system that is every item must be able to fit within the grid. When that’s possible, they offer very dense storage capacity. To keep the stored items accessible to the robot, at the end of the shift, the next shift’s work is re-positioned within the grid so that the products needed most are located near the top. Think of this as somewhat similar to the way tiles can be re-positioned on a Rubik’s cube. Grid systems can run continually, optimizing slotting. They work best in warehouses that need to prioritize storage capacity, but not necessarily picking speed.
How different automated solutions compare on cost
Calculating the true cost of an automated system depends on the ROI and what storage and distribution problems you are trying to solve. For example, the grid system may be the most expensive, but it may have the least cost per square cubic foot. Then again, if vertical carousels and VLMs are sized properly, they can provide very dense storage, as well. Horizontal carousels are probably in the medium price range per cubic foot; however, the speed and accuracy of the picks can make them an optimal solution.