This article presents complete information for selecting a suitable warehouse racking system. Read further to learn more about.
Warehouse racking, also known as storage or pallet racking, is a material handling system designed for the mass storage of goods that are unitized on skids or pallets. It optimizes space utilization while allowing easy access to stored items, thus improving inventory control. This system is particularly useful for manufacturers who need to store non-perishable products in large quantities when available storage space is limited. Typically, palletized products can be stacked safely up to three layers. However, a racking system allows for stacking palletized products five to seven layers high, depending on the height of the facility, thereby maximizing storage capacity.
In addition to handling finished goods, racking systems are also utilized for the storage of raw materials and parts. Selective racking can be designed to maximize the number of accessible items, accommodating a high variety of products. Some distribution systems prefer the FIFO (First-In, First-Out) method of inventory control, which ensures that the oldest items in the warehouse are accessed and off-loaded first. This approach helps in managing inventory efficiently and reducing the risk of product obsolescence.
Aside from optimizing storage space, warehouse racking systems offer several other advantages. These benefits can be quantified in terms of economic value, including savings on leasing additional storage space, reduced workforce effort, and increased throughput. Additionally, compliance with safety standards and quality management, while not always directly translating into immediate financial savings, adds significant value. Below are some of the key benefits of implementing a warehouse racking system:
Easy inventory organization: Racks can be addressed easily in comparison to stockpiling. Storing goods with many distinct varieties is virtually impossible with stockpiling without consuming large floor spaces. A type of racking system known as selective racking allows storing different types of goods while keeping the consumed space to a minimum.
The evolution of racking systems was driven by the need to prevent damage to goods and products. Originally constructed from wood, these systems have advanced to highly stable metal structures, capable of stacking goods several feet high, limited only by the height of the facility.
Palletizing materials simplifies the organization of shipments and the receipt of supplies. A racking system securely stores palletized materials, protecting them from mishandling, accidental contact, or falling. The metal frames of the racks prevent pallets from shifting and act as a protective barrier. With various designs available, from two-deep configurations to extremely tall systems, racking ensures easy access to goods without disturbing surrounding pallets.
In a racking system, the location of an empty pallet can be easily identified and accessed, reducing unnecessary movements. Over time, this efficiency prevents small actions from accumulating into significant losses.
Adapting a racking system is the first step to warehouse automation. This is achieved by integrating smart conveyor systems and guided forklifts and cranes. This can lead to significant savings in terms of manpower costs and can streamline the business process especially for large distribution centers.
Warehouse racking systems are designed to maximize storage space, organize products efficiently, and facilitate item retrieval through effective cataloging. Safety measures are crucial to maintaining warehouse efficiency and are integral to racking system design. These safety features include sensors and alarms, guard rails, rack end protectors, rack guards, and column guards.
Improved access facilitates easier cleaning of goods and storage areas. Additionally, better segregation of items can be achieved, helping to separate goods that may deteriorate or potentially damage adjacent items.
Before investing in a racking system, it's important to consider several factors to assess the project's viability. Although racks optimize space, they also occupy some of it with their frame and accessories. One significant drawback is the difficulty in modifying or reconfiguring the system once installed. To maximize your investment, keep the following points in mind:
Vertical Clearance: Aside from the available horizontal space, also assess how much vertical space can be utilized. Available vertical clearance directly influences the storage racking density. Adding one or two layers to an existing three-layer pallet stack can even decrease the storage density due to less utilization of the floor area. Racking systems that take advantage of vertical slopes, such as gravity flow systems, can further decrease the storage density by removing a layer to accommodate the required slope. Moreover, it is important to take note of the required clearances for fire suppression systems and obstructions for airflow. Elevating the stack height may defeat the design features of these systems and may call for modifications that further add to the initial cost of the project.
Load: The frame must be able to support the pallet load by selecting the appropriate material. Most racking systems are made of steel but are created through different manufacturing methods. For lighter loads, cold-rolled steel is sufficient. On the other hand, heavy-duty applications require structural steel that is formed through hot rolling or extrusion.
Number of SKUs: A stock keeping unit, or SKU, the number of distinct types of goods. It can also refer to the code or designation given to a specific item for inventory management. Determining the number of SKUs to be stored will help balance between selectivity and storage density of a warehouse racking system. Prioritizing either selectivity or storage density will determine which type of racking system is required.
Racking systems come in various designs and configurations tailored to specific applications. Generally, storage racks are categorized into high-selectivity, low-density or low-selectivity, high-density applications. High-selectivity, low-density racks include selective, double-deep, and very-narrow-aisle systems. Conversely, high-density applications encompass push-back, drive-in, and pallet flow systems. Additionally, there are specialized systems, which are essentially adaptations or modifications of these standard configurations.
Selective pallet racking is designed for high SKU counts but offers lower storage density. It is often visualized as large shelves with space for a single row of items. Although racks can be arranged back-to-back to enhance storage density, the overall density remains low due to the space occupied by aisles. This type of racking is commonly used in warehouses for raw materials, parts storage, and distribution centers where there is a wide variety of products in low volumes. Selective pallet racking can be combined with other racking types to handle SKUs with higher volumes. Key benefits include flexibility for FIFO and LIFO inventory management, compatibility with standard forklifts, ease of cleaning and inventory management, and straightforward construction that allows for easy reconfiguration. Selective racking also features various frame and beam connection designs, including teardrop and slotted racks.
Teardrop Racks: Teardrop racking is a type of selective racking with modified frame and beam attachments that can be reconfigured and expanded easily without the use of machine tools. Upside down teardrop-shaped holes are punched along the upright frames, where pins attached to the beams are inserted. As the pin falls into the tapered opening, friction secures it in place without requiring additional fasteners. This connection has enough strength to be comparable with permanent joints. Adding heavier loads causes more friction to fix the beam in place. Wire decks are placed above the beams that become shelves for the pallets. Appurtenances such as pallet supports, crossbars, ties, and anchors are added to further strengthen the structure. Teardrop pallet racks are usually produced by roll forming in which metal sheets are cold-rolled into rectangular frames and beams.
Slotted Racks: These are sometimes referred to as structural racks. Instead of using upside-down teardrop-shaped holes, slotted racks have a pair of rectangular openings milled along with the upright frame. The frame and beam can be attached by hooks protruding from the beam or by bolts. The main advantage of using slotted racks over teardrop racks are their higher durability and strength. Slotted racks are produced from hot-rolled structural steel, making them more robust than teardrop racks. Higher gauges of sheet metal are used to allow a higher load-bearing capacity. The downside of using slotted racks is their higher cost and weight.
Double-deep pallet racking is an enhancement of standard selective racking, where each pallet shelf holds two rows of pallets instead of one. This modification increases storage capacity by 40-60% while retaining many of the benefits of traditional selective racking. For FIFO inventory management, adjacent rows must contain the same SKU, which improves storage density but reduces selectivity. A notable disadvantage is the requirement for specialized forklifts or standard forklifts equipped with double-deep handling attachments, leading to higher operating costs and the need for well-trained operators.
The concept of very narrow aisle (VNA) racking is to enhance space utilization while maintaining 100% selectivity, building upon the standard selective racking system. This is achieved by using a side-loading forklift, which allows pallets to be loaded and unloaded without the need for wide aisles. By minimizing aisle space, VNA racking can reduce the aisle width by up to 40%. However, a drawback of this system is the requirement for two types of equipment: a side-loading forklift for accessing the racks and a standard forklift for transporting pallets between the palletizing station and staging area.
Push-back racking involves loading pallets onto carts that rest on rails within each lane of the racking system. These carts are positioned at the front of the aisle and are designed to nest together. To load a pallet, a forklift pushes the pallet into the lane, causing the existing pallets to move further back. This dynamic system enables higher storage density compared to single or double deep racking. Each lane typically holds one SKU and can be configured to accommodate three to six pallets deep. Because the pallet being accessed is always at the front of the lane, specialized deep-handling forklifts are not necessary. The lanes are inclined to facilitate the rolling of carts towards the aisle. Note that this system operates on a Last-In, First-Out (LIFO) basis, as only the most recently loaded pallet is directly accessible.
In this racking system, pallets are supported by a pair of rails specifically designed to match the dimensions of the pallets. These rails enable the forklift mast and forks to access the pallet as it moves along the bay. Loading is performed by driving the forklift into the last available position within the bay. Once in position, the pallet is carefully lowered onto the rails. After loading, the forklift mast is retracted, and the forklift exits the bay. Each bay is dedicated to a single SKU and can hold multiple units deep, making this system suitable for high-density storage with lower selectivity. There are two primary configurations: drive-in and drive-through. In a drive-in system, there is only one access point for both entrance and exit, which supports Last-In, First-Out (LIFO) inventory management. Conversely, a drive-through system features two access points—one for loading and one for unloading—facilitating First-In, First-Out (FIFO) inventory management.
This racking design uses roller beds to move pallets into the last available position within a lane. The lane features two openings, one at the front and one at the rear, similar to a drive-through system. Pallets are loaded from the rear and roll towards the front of the lane due to the rearward incline of the lane. Off-loading occurs at the front side of the racks. Like drive-in and drive-through racking systems, pallet flow racks are ideal for high-volume, low-SKU applications. This system supports First-In, First-Out (FIFO) inventory management. Although it offers similar storage density to drive-through racks, it does not achieve the same density as drive-in racks due to the use of two lanes. Additionally, the pallet flow system is less susceptible to damage from forklifts, reducing the risk of structural collapse compared to other racking systems.
This type of racking system is ideal for storing long products such as roofing materials, pipes, tubes, and lumber. It features upright columns with cantilever arms extending from one or both sides. The vertical spacing between the arms can be adjusted to accommodate the size and bulkiness of the products, and the angle of the arms can be adjusted to ensure secure load retention. Unlike standard selective racking, cantilever racks do not have front upright frames that obstruct loading, making them particularly suitable for storing long or irregularly shaped items such as appliances and furniture.
This racking system operates on a principle similar to pallet flow racking. It features two access points: one for loading and another for off-loading. Manual loading and off-loading can be done without the use of forklifts, making it ideal for high-volume piece-pick applications, such as in cold storage and food warehouses. Carton flow lanes can also accommodate non-standard-sized items, enhancing flexibility and efficiency in storage.
This method requires shifting an entire rack assembly sideways to open up an aisle. This shifting is typically done using electric motors, though smaller racks might be moved manually or through mechanical means like handwheels. This system offers high-density storage and great selectivity but requires moving the racks to access stored items, making it ideal for warehouses with minimal traffic.
As the name suggests, this type takes advantage of having high bays. They are most suitable for automated distribution centers for high density, high selectivity, and high throughput storage. The racks can be single, double, or in some instances, multi-deep rows. Automatic cranes with telescopic forks or order-picking trucks stabilized by rails and supports move along the aisle. The crane picks up a pallet from the conveyor system and places it on its designated rack. Due to the complexity and high cost of this system, it is only viable for warehousing that hedges profits on efficient storage.
Chrome wire shelving offers great versatility and affordability while matching the strength of stainless steel. It boasts a sleek appearance and is suitable for storing various items, including trays, cartons, boxes, and storage containers, thanks to its robust durability.
Epoxy-coated shelving, available in colors like gray, black, or green, is perfect for damp and humid settings. Certain epoxy shelves come with antimicrobial properties to inhibit bacterial growth, making them particularly suitable for use in the food industry and healthcare environments.
ASRS (Automated Storage and Retrieval Systems) leverage software, computers, and robotics to streamline and enhance the efficiency of handling, storage, and picking processes. These systems can be tailored to accommodate various warehouse sizes and rely on a range of technologies to automate warehousing functions.
Numerous types of ASRS systems are available, each designed to address different warehousing requirements. The most frequently used systems include:
Horizontal Carousels - Horizontal carousels are a form of sorting device used with small parts and products. They can be activated by a computer program or an electronic switch.
Vertical Carousels - Vertical carousels operate like horizontal carousels and have the same activation mechanisms but complete their function vertically rather than horizontally.
Instead of carts or roller beds, this system employs remote-controlled shuttles for lifting, lowering, and transporting pallets. The lane length is not constrained by inclines, allowing shuttles to accommodate a large number of pallet positions per lane. This system supports both FIFO (First In, First Out) and LIFO (Last In, First Out) inventory management methods.
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