In the field of warehouse management, businesses are increasingly choosing automated material handling solutions. These are also known as automated storage and retrieval systems (AS/RS).
The purpose of automation is multifaceted. The primary reason that companies choose to automate is to increase efficiency: machines can improve productivity significantly. Another reason is to reduce the incidence of workplace accidents and injuries, resulting in lost work time.
There are various automated storage solutions available for the warehouse, but two of the most common are the vertical lift module (VLM) and the horizontal carousel.
What is a Vertical Lift Module?
A VLM consists of two vertical storage columns located parallel to each other in a single automated storage system. This system features an extractor that retrieves and stores inventory using trays.
A VLM can significantly increase an order picker’s productivity, as it’s no longer necessary to have an employee retrieve or load inventory from several different locations.
There are also vertical carousels, which operate like a Ferris wheel, using a series of shelves/baskets linked by a chain.
What is a Horizontal Carousel?
A horizontal carousel system uses a series of horizontally rotating shelves, baskets, or other storage devices running on an oval-shaped track. This system is relatively low-maintenance, durable, and ideal for distribution centers.
Pros and Cons
What are the strengths and weaknesses of both systems? Why do some warehouse operators choose one over the other? Both have their pros and cons, depending on the layout of your facility, budgetary constraints, and other factors unique to your warehousing operation.
However, regardless of the system you choose, both offer increased picking accuracy compared to human order pickers while maximizing storage space relative to traditional shelving units.
VLM systems are designed to increase storage density by increasing verticality. Horizontal carousels, however, require more warehouse floor space to operate. So, if you intend to expand your warehouse horizontally, a carousel system does provide a suitable high-density storage solution.
However, if horizontal space is limited, the VLM system offers a comparatively small footprint, increasing the available floor space considerably. Regardless of the differences between the two automated systems, both save space compared to conventional non-automated racking and shelving systems.
One of the considerations that you must remain aware of regarding a VLM system, in particular, is the clear height. The clear height in a warehouse is the usable distance between the floor and the lowest hanging object from the ceiling. This could be a sprinkler system, lighting system, or overhead crane.
The clear height is critical to determine because the ceiling height may not be the limiting factor. As VLM systems minimize horizontal space by extending upward, you should be aware of the clear height of your warehouse and plan accordingly.
Horizontal carousel systems are exposed, using open baskets, bins, or other receptacles to store and transport inventory. The common security solution for this type of system is to use a protective wire-mesh fence.
However, this can impede the efficiency of retrieval and may increase the horizontal footprint. In a warehouse where floor space is at a premium, this may not be the ideal system for securing inventory.
A vertical lift module, however, is a fully enclosed system resembling a large rectangular box. The inventory is protected inside from theft without contributing to the system’s footprint.
One of the most pressing concerns regarding any warehousing business is cutting costs. Automated alternatives to human order pickers are expensive. However, automated systems make up for the high initial capital outlay thanks to gains in productivity.
The difference in cost between VLM and horizontal carousel systems is significant. The horizontal carousel is the less expensive of the two systems.
How do the different systems handle products of different sizes? Horizontal carousels are more limited regarding the sizes and weights of products, as these are set during installation.
A VLM system can read the size of stored items and determine where to place them. Unlike vertical carousel systems, a VLM uses a sensor and a software program to decide where to store trays containing inventory, allowing you to store a more varied product mix.
While warehouses and distribution centers often combine horizontal carousels with conveyor belts, both for order retrieval and loading new inventory into the system. However, you can integrate conveyor belts with either system. When combined with batch picking, a conveyor system can also further increase picking rates.
Which is Best?
VLM systems are ideal for those warehousing operations where the ceiling height is not restrictive, but horizontal space is at a premium. If the inventory you’re storing poses ergonomic challenges or the product mix changes frequently, vertical lift modules are the preferred option.
Horizontal carousels are ideal for warehouses where ceiling height is restrictive but horizontal space is available. These systems are also less expensive to install and operate.
Whether you choose a vertical lift module or horizontal carousel, we specialize in storage solutions for your warehouse or factory. If you’d like more information on the use and selection of automated material handling equipment, call us at (800) 589-7225.