Warehouses are becoming more complex and challenging spaces to manage, due to labor shortages, rising inventory complexity, and demand for faster order fulfillment. As a result, more businesses are turning to automated storage systems to improve efficiency, optimize inventory management, and maximize storage density.

The only problem is deciding which automated system to use, and many operations choose between a vertical lift module (VLM) and full automated storage and retrieval (AS/RS) systems. Of course, both deliver benefits in efficiency, space optimization, and inventory control, but they each do so in different ways.

As your automation experts, the BoxLogix team compares VLM and AS/RS in this blog to help leaders decide on the best option for their facility.

Key Takeaways

• VLM and AS/RS systems both improve efficiency and storage, but they are designed for different operational needs, inventory types, and throughput levels.
• VLMs are ideal for high-SKU, small-part environments with limited space, while AS/RS systems are better suited for high-volume operations handling larger items.
• Choosing the right system depends on factors like inventory size, space, throughput, scalability, and long-term growth strategy, not just upfront cost.

What Is a Vertical Lift Module (VLM)?

Before comparing the two, it’s important to have a clear understanding of what each system is and where it’s used. Here’s a closer look at vertical lift systems.

How a VLM Works

As the name implies, vertical storage systems make the most of vertical space, arranging storage trays vertically inside a self-contained, enclosed cabinet. When an operator requests a specific item, the internal extractor system retrieves it and delivers it to an access window near the unit’s base.

What VLMs Are Designed to Solve

This dynamic storage solution solves numerous problems in many warehouses. Instead of forcing employees to manually make their way around to search for and retrieve products, the vertical carousels of the VLM do it for them.

The modules’ goods-to-person deliveries save walking time, improve efficiency, and ease strain on workers. They also minimize errors by improving picking accuracy, and they’re highly useful in warehouses with floor space constraints, offering high storage density with a small storage footprint.

Typical VLM Applications

VLMs are regularly used for storing the likes of manufacturing parts, aerospace components, and medical/pharmaceutical inventory. They are also commonplace in maintenance and repair operations (MRO), as well as in spare parts distribution centers.

What Is an Automated Storage and Retrieval System (AS/RS)?

Now, let’s take a closer look at automated storage and retrieval systems, including how they work and where they’re used.

How AS/RS Systems Work

AS/RS systems make use of various pieces of equipment, including cranes, robotics, shuttles, and software integration to move and deliver inventory around a warehouse environment. They also often feature specially engineered racks that are taller and closer together than they would usually be, in order to get more value out of the available floor space.

What AS/RS Is Designed to Solve

AS/RS systems are often part of large warehouse redesigns or expansions. They transform how facilities store inventory and move it from place to place in high volumes and densities, speeding up fulfillment and easing pressure on workers.

These systems automate handling of totes, cartons, pallets, and even heavier loads. Integrating with warehouse management systems (WMS) and other software, they solve many of the challenges associated with high-density storage.

Typical AS/RS Applications

AS/RS systems are most commonly found in larger warehouses and distribution centers. A few examples of these include high-volume manufacturing locations, logistics warehouses, and e-commerce fulfillment centers.

VLM vs. AS/RS: Key Differences That Impact Your Operation

The differences between VLM and AS/RS become most apparent when you look at how each system performs across core operational factors. From the types of inventory they handle to how they scale over time, each solution has distinct advantages.

Key comparison points include:

• Inventory type
• Warehouse footprint and space utilization
• Throughput and operational speed
• Investment and implementation
• Scalability

Inventory Type

VLM systems are generally focused on small to medium items, since they only have limited space inside their vertically-arranged storage trays. They’re often employed in high SKU environments.

AS/RS systems, meanwhile, are more capable of working with larger items, like cartons, totes, and pallets, and don’t face the same size restrictions as VLMs.

Warehouse Footprint and Space Utilization

A VLM offers a lot of storage capacity with a relatively small footprint, since it stores items vertically. Users can fit these units into existing unused spaces around their warehouses.

AS/RS systems take up much more room, since they involve larger and more diverse material handling equipment, from robots to engineered racks. Installing such a system often involves major layout changes, but it often delivers game-changing benefits in speed and efficiency.

Throughput and Operational Speed

VLM speeds up parts picking dramatically. Units can rapidly respond to user requests, find specific trays, and deliver the requested goods to the window. Operators, meanwhile, don’t have to walk around and can simply remain stationary beside the unit, waiting for their parts to arrive.

On the other hand, AS/RS units optimize throughput of large-scale, high-volume movement across the entire warehouse. They store, find, and move entire cartons, pallets, and other heavy loads from A to B far faster than conventional teams and equipment ever could.

Investment and Implementation

VLMs are almost always the cheaper of the two in terms of up-front costs. They’re also quicker to install and start using, as they can usually be added to existing warehouses without having to shut parts of them (or even the entire facility) down.

AS/RS systems will demand a larger investment of both money and time. They involve more equipment and often require structural and layout changes to large parts of the warehouse space, like racks being heightened and repositioned closer together.Scalability

VLMs offer lateral or horizontal scalability, as users can simply buy and install additional modules if they find themselves with more demand or additional SKUs to manage.

AS/RS systems can scale in more diverse ways. Operators may install additional racks and aisles, for example, or deploy additional pieces of equipment (i.e., cranes, shuttles, and robots).

When a VLM Is the Right Choice

A VLM is the ideal option for warehouses that have high SKU counts and tend to focus mostly, or exclusively, on smaller items, like manufacturing parts.

They’re also well-suited for warehouses that are limited in terms of floor space, which could use some improvements to product organization and picking accuracy.

Finally, they’re the better choice for users who want to see a rapid ROI without having to completely redo their warehouse.

When AS/RS Makes More Sense

An AS/RS system is a superior choice in facilities that deal with larger goods and higher volumes of products, involving crates and pallets, rather than smaller products and diverse SKU parts.

They’re built for large distribution centers seeking to deploy comprehensive automation strategies, involving not just material handling equipment, but software, too.

They’re also aimed at companies that want to future-proof their facilities and make more of the space and resources available to them.

Can VLM and AS/RS Work Together?

Absolutely, VLM and AS/RS can work together. Many modern warehouses now deploy hybrid automation, a custom solution that combines both VLM and AS/RS technologies to meet the facility’s needs and optimize its operations.

You can have VLM units managing your small parts inventory, while AS/RS cranes and robots take care of pallets and larger loads. All of your equipment can then be integrated through WMS or warehouse control systems, providing complete control and total transparency into your operations at any given moment.

How to Decide Which Automation System Is Right for Your Facility

Deciding on the right automation system is a question of evaluating not one but several factors concerning your current and future operations. You should consider:

• Inventory size and weight: VLMs are good for smaller parts, but AS/RS handles larger items.
• SKU count: VLM units are often best in high SKU spaces.
• Throughput requirements: AS/RS will deliver the biggest differences in high-volume throughput.
• Available space: VLMs take up less room, but AS/RS systems help you extract more value from all of the space available to you.
• Labor costs and shortages: Both systems can ease pressure on your workforce, but AS/RS will have a more dramatic impact.
• Growth projections: AS/RS systems can future-proof your operations even in cases of rapid or sudden growth.
• Capital investment strategy: VLMs are cheaper, but AS/RS may provide greater long-term ROI.

Final Thoughts: Invest in Automation Today

Both VLM and AS/RS systems will improve warehouse efficiency, but one option may be better suited for your space than the other. The right choice depends on what products your warehouse holds and how it moves inventory, with VLM excelling in parts optimization and AS/RS working best for high-volume optimization.

To learn more about these systems or get expert advice on which one to choose, contact the BoxLogix team today.

Frequently Asked Questions (FAQs)

What is the difference between a VLM and an AS/RS system?

The difference between a VLM and an AS/RS system comes down to how they store and move inventory. VLMs are designed for smaller items with vertical, goods-to-person delivery, while AS/RS systems handle larger loads and automate movement across the warehouse.

Which is better: VLM or AS/RS?

Neither VLM nor AS/RS is universally better. It depends on your operation. VLMs are ideal for smaller parts and limited space, while AS/RS is better suited for high-volume environments and larger inventory.

Is a VLM cheaper than an AS/RS system?

A VLM is typically cheaper than an AS/RS system in terms of upfront cost and implementation. It can often be added to an existing facility with minimal disruption, whereas AS/RS usually requires a larger investment and more extensive changes.

How do you decide between VLM and AS/RS for your warehouse?

Deciding between VLM and AS/RS depends on your inventory, space, throughput needs, and growth plans. VLMs work well for high SKU environments with smaller items, while AS/RS supports larger loads and higher volumes. The right choice should align with both your current operation and future scalability.

What factors should you consider before investing in warehouse automation?

Before investing in warehouse automation, you should consider inventory size, SKU count, throughput requirements, available space, and labor challenges. It’s also important to evaluate your growth projections and capital investment strategy to ensure long-term value.