Vertical carousel vs vertical lift module: Know the differences to make the right choice

Quick, off the top of your head: What’s the difference between a vertical carousel and a vertical lift module? If you said they’re the same thing, you’re not alone. Even those who own vertical lift modules sometimes mistakenly refer to them as vertical carousels. But there are important differences worth understanding if you’re in the market for an automated, vertical storage system. In this article, we’ll explore the mechanical, operational, and cost differences to help you make an informed decision.

Introduced in the 1950s, a vertical carousel is like a Ferris wheel that stores small parts or files and rotates to deliver them. It consists of trays attached to a chain that rotates. Like a Ferris wheel, it is primarily designed to carry items of similar size and weight.

Introduced later, a vertical lift module has a more advanced design and operates like a vending machine in which items can be retrieved without rotating everything stored inside. An inserter/extractor grabs individual trays from where they sit in the machine, delivers them to a bay, and then returns the tray to its initial position. 

Because the vertical carousel came first, that term seems to have stuck for the entire category. For our purposes, we’ll just abbreviate the two: VC for vertical carousel, VLM for vertical lift module.

In the majority of applications, VLMs have clear advantages. They are more space-efficient, can carry heavier objects and more overall weight can typically operate more efficiently, and are readily modified if there are changes in the types of items being stored.

VCs can be used effectively primarily when an organization needs daily access to records, such as a healthcare organization accessing patient files. If the organization doesn’t need daily access to such files but instead requires long-term storage, a VLM is far better. Thanks to a height-detection system, the height of the products in the tray is measured as the tray is put away, allowing the densest storage location to be determined in real-time.

The problem with vertical carousels

If you recall how people get on and off a Ferris wheel, you’ll see what the issue is with VCs. To make sure the load is evenly distributed along the wheel, passengers are seated in one “car,” then the wheel is rotated 180 degrees to load the next set of passengers. If they all were loaded in adjacent cars consecutively, the wheel would quickly become unbalanced and the Ferris wheel would tip over.

Similar considerations have to be made when loading a VC. Items need to be of similar weights to avoid load imbalances. They should be of similar sizes to optimize the storage space because the tray positions cannot be changed. Nor can a VC be too tall – a maximum of about 25 feet while VLMs can be well over 50 feet tall – due to the inherent instability of a VC.

Vertical Carousel - how it rotates as a ferry wheel

The advantages of vertical lift modules

The operational differences between a vertical storage carousel and a vertical lift module become apparent when you look closer:

Maximize Storage Potential
VLMs can readily accommodate items of various sizes and automatically adjust their trays to maximize storage density. VCs are stuck with a set amount of space between trays.
Picking efficiency & speed
Due to their varying retrieval methods, VLMs can save time in picking items. There’s no waiting for the entire set of trays to move – just the one holding the required item. With the greater range of visual aids that VLMs can provide (laser pointers to indicate where the required item is located, for example), they provide a much faster and accurate retrieval for the operators.
Integration with picking aids
VLMs can be easily integrated with external picking aids, making them the best solution for heavy items where the operator needs to rely on lifting assistance to safely handle the goods.
– Installation time
VLMs come in separate pieces that can be more readily transported. VCs are less flexible to install because their end frames are one solid piece and are not always easy to move into a location. While a VLM can be installed in 2 days, a VC will usually take 4 days.

Vertical Lift Module advantages

Comparing vertical carousels with the Modula Slim vertical lift module

Modula’s Slim represents the most direct comparison of a VLM to a typical VC. It’s designed for smaller installations in which the organization is retrieving small- to medium-sized parts.
Unlike most VCs, the Slim can be ordered in widths as small as 51 inches, while VCs typically are 90-96 inches wide. Slims can also be configured to reach up to 23 feet and hold more weight – up to 772 lbs (350 kg).
 
And of course, all the benefits of vertical lift modules mentioned previously are included with the Slim.

Difference in payload capacity - VC vs VLM

Due to their long history, vertical storage carousels are relatively abundant, which means they often sell at relatively low prices on the used market.
But often they represent a false economy.

To begin with, there are the installation obstacles of merely getting the vertical storage carousel into your facility, as mentioned earlier. In addition, you’ll need to have it certified for safety. And while the external surfaces might look fine, the inner workings may not be up to par. Worn parts, bad circuit boards, problematic wire harnesses – all of these can represent hidden costs that make a used VC seem much less of a bargain than it initially appeared. And a used VC is likely to come with a very short warranty, unlike the Slim, which has a two-year warranty.

Why choose an outdated technology when the market offers a much more sophisticated and efficient solution?

What about ROI for vertical carousels and vertical lift modules?

The price of a new vertical carousel and a Modula Slim are roughly the same. However, you buy a vertical storage system to boost operational efficiency. Those efficiency gains factor into recouping the initial outlay and you see a quicker ROI for the Slim than a vertical carousel. Because the Slim is easier to load, offers more storage flexibility, can hold more weight, and can provide faster throughput, it’s the clear winner in overall efficiency. That, in turn, means a quicker ROI and a machine that will serve your needs not just now but in the years to come.
 
Want to talk about your storage needs? Contact us. In the meantime, read about the Slim or any of the other VLMs that Modula offers here.