The Different Types of Automated Storage and Retrieval Explained

by Prime Robotics
May 17, 2024
asrs,as/rs,automated storage retrieval system

Which type of AS/RS is right for your warehouse? We break them all down here.

Automated storage and retrieval systems (AS/RS) are revolutionizing how warehouses store, manage, and retrieve inventory. These systems combine equipment and software to autonomously place and retrieve goods from specific storage locations. 

AS/RS optimize warehouse space and reduce costs, while improving overall throughput. Below, we explore the different types of AS/RS and their operational benefits.

1. Unit-Load AS/RS

Unit-load AS/RS are designed to handle heavy loads on pallets. They use deep-lane storage, where multiple pallets are placed and stored in a compact space. These AS/RS are most commonly found in industries that handle large volumes of product, such as manufacturing and distribution centers. 

The main benefit of unit-load AS/RS is their ability to maximize vertical storage space and manage bulk quantities. These systems store pallets in vertical rows, using less floor space and allowing more goods to be stored in the same footprint. These systems also reduce the risk of damage to goods by reducing product touches and speeding up the handling process. 

2. Mini-Load AS/RS

Mini-load systems are similar to unit-load, but as the name implies, are smaller. Typically, items in these systems are stored in cartons, totes, or trays. These systems are ideal for managing loads that are too small for pallet storage but too large for micro-load systems, which store individual totes or cartons. They use smaller, agile machines to store and retrieve items from storage. 

Mini-load AS/RS are the ideal solution for storing and retrieving small and light products that have high stock turnover, such as e-commerce order fulfillment. Warehouses use these systems to more accurately pick products, accelerate order fulfillment, and reduce labor costs. The compact design of this system also results in more efficient use of storage space and can be adjusted to fit many different sizes and weights. 

3. Carousel Systems

There are two main types of carousel systems: vertical and horizontal. Both of these systems work well for high-density storage and are used in a variety of settings. Carousels accelerate picking speeds and integrate with software to sequence systems to minimize wait time for retrievals. 

Vertical Carousel Modules

Vertical carousel modules are a series of shelves or carriers that rotate vertically around a track, like a ferris wheel. Stored items are then brought to the operator at an ergonomic height, eliminating the need for physical climbing or reaching. 

These systems are excellent for optimizing vertical space and saving floor space. Since items are delivered at a comfortable working height, the risk of strain or injury for workers is minimized. 

Horizontal Carousel Modules

Horizontal carousel modules have a series of bins or shelves that rotate horizontally on an oval track. This allows workers to access multiple bins from one picking station, which streamlines the picking and retrieval process. 

These systems are best for high-speed picking, giving workers access to a variety of items at once. The carousels are arranged in workstations or pods, and the access point can be adjusted to create the most efficient layout. These systems are typically less expensive than vertical carousels. 

4. Vertical Lift Modules (VLMs)

Vertical lift modules (VLMs) use two columns of trays to store and transport goods, with an extractor in the center to adjust them as needed. VLMs deliver trays to a comfortable position at the workstation, giving workers easy access to stored items. 

These systems are best used in warehouses where there is minimal floor space, as they store materials of all sizes vertically. They also minimize unnecessary movement, which reduces worker fatigue and increases productivity. 

5. Mobile Shelving Systems 

Mobile shelving systems have shelving units mounted on mobile bases that glide along tracks. This setup allows for compact storage of items by eliminating the need for multiple fixed aisles. 

Mobile shelving systems are ideal for archives like libraries and retail storerooms due to their impressive space savings. They are also highly flexible and manage variable inventory sizes. They can be controlled manually or electronically, allowing workers to access stored items easily. 

6. Robotic Cube-Based AS/RS

Robotic cube-based AS/RS use a high-density storage grid and robotic shuttles that operate on three axes: X, Y, and Z. These systems use robots to store and retrieve bins that are stacked on top of each other inside a cube.

One of the top benefits of cube-based AS/RS is that they maximize both vertical and horizontal space. They can also be easily scaled up or down by adding or removing cubes or robots. These systems are best used in industries with a high volume of small to medium-sized items, such as pharmaceuticals and cosmetics. 

7. Pallet Shuttles

Pallet shuttles are automated or semi-automated self-guided vehicles that store and retrieve pallets within a deep lane storage system. Pallet shuttle vehicles navigate up and down the racks to load and unload pallets. Pallet shuttles maximize warehouse space by storing pallets vertically and reducing the need for aisles between racks. They also save time and reduce traffic caused by forklifts driving into storage lanes to load and unload pallets. 

Because forklift drivers no longer need to enter the racks to store and retrieve pallets, pallet shuttles reduce the risk of accidents associated with manual labor. Pallet shuttle systems are versatile and scalable, with the ability to easily add more shuttles and accommodate different pallet sizes and weights. These systems are ideal for warehouses with high throughput and large volumes of single-SKU or multi-SKU pallets, such as the food and beverage sector. 

Final Thoughts

Automated storage and retrieval systems come in many shapes and sizes and allow warehouses to maximize their storage capacity differently. From unit-load systems to pallet shuttles, each system has unique benefits. It’s important to evaluate your warehouse environment and processes to select the right system to meet your needs. 

Contact us to schedule your workflow assessment and discover how Prime’s high-density pallet shuttles improve warehouse space utilization and operational efficiency.

Prime Robotics