Automated stacker cranes: definition and applications

Automated stacker cranes have become practically indispensable in Logistics 4.0 because they’re the perfect solution for boosting efficiency in warehouses with a high flow of movements. 

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There are different types of stacker cranes available on the market — for both boxes and pallets — depending on the logistics needs of each company. Knowing all about the characteristics of an automated stacker crane will enable you to get the most out of your supply chain. 

Automated stacker cranes defined

Automated stacker cranes are handling equipment that moves horizontally and vertically in the storage aisles of a logistics facility. They’re tasked with transporting, storing, and retrieving goods from their locations in the racks by using extendable forks installed in the cradle of the machine. 

Stacker cranes can operate in single- or double-deep pallet racks, pallet flow racks, and can even work with a motorized shuttle (the automated Pallet Shuttle system). This equipment is a vital part of any automated storage and retrieval system (AS/RS) for pallets and is especially useful in warehouses with high-turnover products and continuous inflows and outflows.

Storage and extraction operations can be performed independently (simple cycle) or jointly (combined cycle). The simple cycle refers to the natural movement a stacker crane makes to store a single item. With the combined cycle, the stacker crane deposits a load and picks up another in a single movement. Thus, combined cycles reduce movements, streamlining flows.

Benefits of automated stacker cranes

The main advantages of automated stacker cranes are related to automation. As these machines work nonstop, the flow of movements increases considerably, while errors are minimized. In other words, they offer a high degree of efficiency and productivity. 

Another advantage of automated stacker cranes is space optimization, as they leverage every inch: they can move goods up to 148' high and move in aisles merely 5' wide, making it possible to create high-capacity facilities. 

Problems solved with an automated stacker crane

The implementation of automated stacker cranes represents a step forward for a company’s supply chain efficiency. That’s why businesses with high-turnover stock and constant entries and exits turn to this solution to speed up their storage operations.

Automation in an already existing warehouse

AS/RS trilateral stacker cranes allow for easy automation of facilities with pallet racks without modifying their structure. Since they don’t require an upper guide rail, they can be installed in any warehouse in which trilateral turret trucks are normally operated. The solution is extremely cost-effective when it comes to modernizing both already existing facilities and new buildings.

Disalfarm, a logistics company specializing in pharmaceutical products, swapped the trilateral turret trucks that served its pallet racks for 15 trilateral stacker cranes from the Mecalux Group. It did this to adapt to the increase in activity it was experiencing. Disalfarm Operations Manager Jaume Segrià says: “We now have maximum process efficiency and optimal safety for everyone inside the warehouse.”

Conventional warehouse over 131' tall

Standard forklifts are incapable of working in facilities requiring height to raise storage capacity. Therefore, automated stacker cranes are the only handling equipment that can operate with racking over 131' high.

Hayat Kimya, a leading manufacturer in the Eurasian fast-moving consumer goods market, built a new logistics center to manage the company’s heightened production and to cut goods inflow and outflow times. The solution consists of one of the tallest automated warehouses in Europe: 151' tall. 

Streamlined picking 

Reducing the time between the receipt of an order and its preparation is one of the biggest challenges facing logistics nowadays, even more so with the e-commerce boom and the rise of quick commerce (q-commerce). With a miniload system (AS/RS for boxes), you can have an automated storage system for smaller products that works in line with the goods-to-person order picking method. Instead of the operator having to move, the stacker crane brings the product to be included in the order directly to the pick station.

Tool manufacturer SAM Outillage gave its logistics operations a makeover with an AS/RS for boxes that enables it to prepare and deliver orders in just 24 hours. Automation minimizes errors and reduces the number of movements made in the warehouse. SAM Logistics Manager Candice Aubert says: “The automated warehouse from Mecalux has helped raise our productivity by 25%.”

Automation of a high-density warehouse

One of the best storage solutions for dealing with space shortages and optimizing surface area is to install a compact system. Stacker cranes speed up flows of goods with these types of racks, which have only the necessary working aisles, since the structure is compact. 

Finieco, one of Europe’s largest paper bag manufacturers, turned to the Mecalux Group for a storage system that would maximize space in its logistics center in Portugal and, at the same time, ensure a high throughput. After exploring various options, it decided on the automated Pallet Shuttle system served by an automated stacker crane. Now, the warehouse makes the best use of all available space. Plus, as it’s connected to the production zone, it’s capable of absorbing the daily manufacture of 1.5 million paper bags.

Uninterrupted work at low temperatures

The main drawback with cold storage and freezer warehouses is working with manual storage systems in extreme environmental conditions. Exposure to low temperatures for long intervals can adversely affect the health of operators.

To avoid this, automated stacker cranes are an excellent solution: they can operate at negative temperatures as low as -22 °F, automating the storage and retrieval of unit loads and, thus, significantly limiting employees’ exposure to the cold. Additionally, automation of cold storage warehouses guarantees hygiene in all logistics processes, a key factor in sectors such as the food and pharmaceutical industries.

Congelados Navarra, a leading European producer and marketer of deep-frozen vegetables, automated its four freezer warehouses in Fustiñana, Spain, with automated stacker cranes from the Mecalux Group. With this handling equipment, the business not only stores 160,000 pallets but has also streamlined movements in the goods loading and unloading processes.

Automation of product turnover

Ensuring optimal turnover of the SKUs stored by means of the FIFO (first in, first out) management method is a must when working with food, chemicals, or any other kind of product with an expiration date. One of the most common solutions for making sure the first pallet stored is the first to be dispatched are pallet flow racks. Typically used in conjunction with forklifts, operations can also be automated with a stacker crane. 

Cosmetic and hygiene product manufacturer EcoWipes looked to the Mecalux Group to speed up management of its high-demand raw materials. Hence, our company installed pallet flow racks served by a stacker crane. This machine travels down a 177-foot-long aisle continuously, placing the pallets in the assigned locations as quickly as possible.

Management of different unit loads

One of the great things about stacker cranes is their versatility and capacity for handling different types of unit loads, particularly pallets and boxes. Many companies need to automate the storage and retrieval of these two unit loads. 

Miguélez, a global benchmark in the manufacture of low-voltage electric cables, implemented two AS/RS (one for boxes and another for pallets) to store its various product types: drums, spools and reels. Automation has brought Miguélez numerous advantages, mainly increased productivity and availability, as it can now work 24 hours a day at maximum throughput. The two automated storage systems store over 38,500 tons of cable.

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Stacker crane installation

The implementation of automated stacker cranes is conditioned by each company’s logistics needs, flows, operations, warehouse characteristics, and products. There’s a stacker crane for every storage height, for the number of cycles required, and for each type of good (covering various sizes and weights, up to 1.65 tons per pallet).

Interlake Mecalux has a wide selection of single-and twin-mast stacker cranes with different extraction systems. As a supplier, it offers models ranging from the MT-1, suitable for facilities with a lower height, to the MTB-7, reserved for warehouses up to 148' tall and with a high volume of goods movements.

Automated stacker cranes: maximum efficiency, safety, and performance

Investing in technology solutions such as automated stacker cranes is the best way to benefit from an effective supply chain and successfully tackle the major logistics issues facing businesses nowadays. In recent years, automated stacker cranes have become essential in Logistics 4.0.

Stacker cranes for pallet storage and retrieval in rack systems were developed in Germany in the early-’s. Early versions were operated via on-board control cabins where an operator controlled the crane much like a forklift, but with taller reach heights and increased product density. By the mid-’s, automated stacker crane systems were being deployed around the world, produced by a wide range of equipment manufacturers. These systems enabled storage at heights exceeding 100ft.

This article discusses the challenges of maintaining and upgrading automated warehouses that were designed, manufactured, and installed over the last 40 years. There are many automated storage and retrieval systems that have been in continual use for 20 to 30 years or more and are ready for an upgrade. New equipment that extends the serviceable life of these assets that are deeply integrated into company operations.

History of AS/RS Applications

Through the late-’s and into the ’s, a large number of systems were installed throughout North America. These early systems were designed with an emphasis on providing increased reserve-stock inventory at the manufacturer level. The systems were not designed for fast performance and high inventory turns. The primary business driver was providing stock on-hand near point of production, while minimizing warehousing space and maximizing space available for production, especially at locations where land for plant expansion was limited.

In the ’s and 80’s demand planning was in its infancy, sophisticated ERP systems and flexible manufacturing weren’t yet buzzwords, and inventory on-hand is what fed the manufacturing machine and kept orders rolling out the door. This period was the heyday for pallet ASRS in North America. As a testament to their durability, many of those systems are still in use today --- companies reliant on systems and machines designed, built, and installed four decades ago!

In the ’s “inventory” was a bad-word and “just-in-time” was the new business mantra. With reduced stock on-hand, there was a drive toward increased system performance. At the same time businesses were working to reduce inventory on-hand, the world began shifting to production based in Mexico, China, Eastern Europe and other lower-cost countries around the world. Just-in-time supply chain planning became the norm, with safety stock measured in days, not weeks or months. Supply chain flexibility was a valued attribute and large warehouses to store inventory did not fit the business attitude of the day.

Automated storage and retrieval systems in the ’s adapted to meet the needs of the new business environment. There was a rapid focus on increasing system performance, allowing higher levels of inventory turns and faster order fulfillment. Promotional literature of the day nearly always touted crane speed as a key product attribute. If your crane didn’t boast speeds of 900 ft/min, you weren’t a real player. Never mind that at those speeds the cranes were hard to control and to regain system reliability the equipment was inevitably slowed down. Cranes of this era are often plagued with structural issues (mast cracking, wheel and rail wear, etc.). The rush to increase performance often outstripped engineering budgets, abilities, and tools available at the time.

The systems of the ’s and early ’s were smaller in size (number of load units stored), but were often high-performance systems deeply integrated into users production and/or order fulfillment operations. This is both the advantage and Achilles heel of the technology. System reliability and availability was critical --- systems down for service often meant that entire production lines came down with them. If you want a technology to get a bad rap, just take down production! From the ’s through the late ’s, most systems were installed at the manufacturer-level, including a large install base in food, automotive, manufacturing, chemical, and pharmaceutical industries.

In the ’s, systems began to be installed by companies in warehousing and distribution, with a number of systems installed by companies for grocery distribution in ambient, chilled, and frozen. The beverage industry (soft drinks and alcoholic) also installed a number of systems; both purely for distribution and as plant-attached warehouses. Through the ’s, a number of systems were installed for the automotive industry, but most systems were used for sequencing buffers, rarely for reserve stock inventory.

Fast forward to ’s and today, and new industry verticals are adopting ASRS technology for both old and new reasons. The cold storage industry has rapidly embraced the technology. Finding people willing to work in a cold storage warehouse has become increasingly difficult (and expensive). Robotic machines that don’t mind the cold are a compelling business case when the alternative is lack of workers at nearly any price. Energy savings is the cherry on top. Ever present is the need to hold inventory (small as it may be) close to the manufacturer, whilst preserving all available space for production expansion.

Grocery distribution has been an aggressive adopter of the technology over the last 10-15 years. The margins are famously tight in the grocery business and automation provides an avenue to squeeze the last few points of cost out of the equation, especially in chilled and frozen applications. The next decade or two is sure to see a resurgence in building supply chain resilience (a.k.a. more inventory) and reshoring manufacturing to be closer to the end consumer. Both factors that point toward increasing adoption of automated storage and retrieval systems.

Operators of automated storage and retrieval systems from the ’s through early ’s are ready for upgrades. New machinery that increases reliability and serviceability. Replacing old machinery means designing new machines to fit the engineered designs from years ago. In the automated warehousing industry, DAMBACH Lagersysteme is the expert at designing new cranes to fit old rack systems, including removal of old equipment and install of new equipment in live/running production environments.

Challenges of Crane Replacement

There are several challenges that make replacement of these old machines difficult: One, new crane models must be designed to fit the racking systems of 20, 30, 40+ years ago – including first load level, top-load level, aisle widths, top-guide-rails, and clearances. Modifying old rack structures (especially rack-supported-buildings) ranges from cost-prohibitive to impossible. Most new crane manufacturers are focused on building standard models for new systems. There are only a handful of crane manufacturers with the engineering ability and manufacturing capability to build drop-in replacement cranes. In the case of specialty aisle-changing cranes, the vendor list worldwide only has a single name on it: DAMBACH Lagersysteme.

Two, many cranes were installed as part of new building construction years ago. Now old equipment must be removed from existing buildings and new equipment installed. DAMBACH has removed and installed cranes using in-rack winch-systems with new cranes built with custom-length mast sections to keep lift weights in a reasonable range. Often adding to the challenge is that over the years, buildings have been expanded and changed, land-locking equipment with surrounding structures. DAMBACH has replaced cranes using helicopters to lift old cranes out and put new cranes in.

Three, these systems are mission critical for nearly every company that uses them. Projects are always split into phases where cranes are removed and installed one at a time. This adds an extra challenge scheduling crews and managing installations, especially when parts of the installation are weather dependent and managing shifting schedules on installation of 400 to 500 cranes per year around the world. It won’t be easy, but it’s not our first rodeo.

If you are an industry old-timer and have some tidbits of knowledge to share about history, I'd be happy to update this article with any clarifications to improve historical accuracy.

If you’ve got an old crane system that needs replacement, give me a call and we'll talk through the options!

DAMBACH Lagersysteme has been producing stacker cranes in Germany since . DAMBACH provides a complete range of cranes from small and light capacities up to heavy and large and everything in between. Cranes are available fixed-aisle, aisle-changing, and multiple cranes per aisle. There are thousands of cranes in operation worldwide in a variety of industries and industrial conditions.

Author: John Ripple - VP Sales at DAMBACH Lagersysteme Inc.

If you are looking for more details, kindly visit stacker cranes for pallets.