This article will take an in-depth look at storage racks.
The article will bring more detail on topics such as:
This chapter will explore what storage racks are and the key factors to consider when designing and selecting them.
Storage racks, also known as racking, are structures designed to store items and materials. They typically consist of at least two vertical frames, horizontal beams, and some form of decking, which can include bars, panels, meshes, or be absent altogether.
When designing storage racks, the following considerations should be taken into account:
When designing a pallet racking system, it's crucial to consider the weight and dimensions of the pallets, including their length, height, and width. The most common pallet size (40" x 48") is widely compatible with most racking systems. This information helps determine the appropriate rack depth and upright height. Additionally, the type of pallet racking system needed may be influenced by the nature of the palletized items:
The number of SKUs and the quantity of pallets per SKU in a warehouse significantly influence the choice of pallet racking system. Selective pallet racking is suitable for facilities with only one pallet per SKU, as it offers variety and easy accessibility for different SKUs. For facilities with multiple pallets per SKU, higher-density storage solutions like drive-in or push-back pallet racking may be more appropriate. Pallet flow racking is ideal for facilities with numerous pallets per SKU that require FIFO (first-in, first-out) inventory retrieval.
The cost of your racking system can vary depending on the climate requirements of your products. Products can be stored in various environmental conditions, including:
The temperature of the warehouse plays a crucial role in maintaining product integrity depending on the type of goods stored. In ambient conditions, temperature is less critical. However, for perishable commodities like food, cold warehouses are essential to keep items at low temperatures. Controlled temperature warehouses are used for items such as pharmaceuticals and cigars, where maintaining a specific temperature range is necessary to preserve product quality.
Environments where temperature control is less critical typically incur lower expenses. In contrast, pallet racking systems for cold environments are usually more costly due to the need for:
Whether a pallet racking system is designed as a retrofit for an existing facility or installed in a newly constructed building can impact the project cost, timeframe, and available warehouse space. Additional key considerations for the building's structure include:
The size and type of material handling equipment, such as lift trucks, forklifts, or man-up order pickers, influence the required aisle width and the number of racking rows. For instance, a standard counterbalance forklift typically needs a 12-foot aisle, whereas man-up order pickers can operate in narrower spaces. Designing a warehouse with fewer aisles is advantageous as it maximizes the available storage space.
Key considerations when choosing storage racks include:
Examine the product line your company sells and categorize items based on density, weight, delivery frequency, and shelf life. This information will help determine the type of rack or shelf required. For example, drive-in racking systems are ideal for bulk storage but may not be suitable for high-selectivity items.
Selective pallet racking is ideal for storing large inventories of small quantities of diverse products. Once you've identified the appropriate racking solution for your products, you can choose based on factors like density and selectivity.
Every department, including the warehouse, must adhere to its budget, making the cost of a pallet rack a crucial consideration. Costs generally fall into three categories: storage, design, and installation. While opting for lower-cost options may seem appealing, it is important to avoid compromising quality in the process.
Experienced warehouse managers often prefer pallet racks with competitive pricing over generic, low-cost systems. Investing a bit more in high-quality pallet racks can be more economical in the long run, as it reduces the need for frequent replacements.
As your company grows, your storage needs will also evolve. Your organization may introduce new products or shift its product line. Therefore, it's crucial to choose pallet racks that can adapt to these changes. Opt for storage racks that allow for adjustments to accommodate both minor and major modifications. Some types, such as cantilever and selective racks, offer more versatility in this regard.
Collapsing pallet racks are a common cause of warehouse accidents, potentially leading to severe employee injuries or product damage, both of which can result in significant financial losses. To prevent such issues, it is essential to use sturdy and durable pallet racks. The storage system should be robust enough to withstand impacts over time, and you must be aware of the weight capacity of the shelves you plan to use.
The different types of storage racks include:
The traditional pallet rack is an economical storage solution that provides direct access to all pallets. It offers a large storage capacity, is easy to install and adjust, and involves minimal equipment and capital expenses. Conventional pallet racks allow for straightforward access to products, making them ideal for handling a variety of items. They simplify stock management and can be adapted to any storage area, size, or product weight.
Each end frame of a pallet rack consists of two uprights, horizontal and diagonal bracings, footplates, bolts and nuts, and anchor bolts. The depth of the frame is determined by the size of the pallet; for example, a frame with a depth of 1100mm is typically used for a Europallet that measures 1200mm deep. Uprights can be customized to accommodate various loading requirements due to their diverse sections and thicknesses. To allow for beam height adjustments, uprights are equipped with symmetric hexagonal slots spaced at 75mm or 76.2mm intervals and are reversible.
Footplates are attached to the base of the uprights to provide support for the frames on the floor. Various types of footplates are available, depending on the load capacity and the model of the upright being used. One or two anchor bolts are employed to secure the footplates to the floor. Anchor bolts ensure that the racks are firmly anchored to the slab.
Footplates vary depending on the forces they must withstand and the properties of the slab. Each beam is equipped with two safety pins (optional: spring safety pins) to prevent dislodging during use. These pins offer extra protection for the sides of the rack base. Typically, safety pins are installed at the ends of frames and in the passages between them, where impacts are more likely. They help shield the racks from light impacts at ground level, minimizing localized damage to the vertical components.
Teardrop pallet racks, also known as rivet pallet racks, differ from conventional pallet racks in that they use rivets instead of hooks for assembly. This type of racking system includes components such as uprights, beams, H bracing, D bracing, nuts, and bolts.
The rivet pallet rack (Teardrop type) is an economical and efficient solution for storing pallets or bulk boxes. It is versatile and can be used in various storage applications, including narrow aisle racks, drive-in racks, double deep racks, carton flow racks, and shuttle pallet racks. This type of racking system is suitable for diverse warehouse layouts and applications such as bulk storage, carpet storage, drum storage, cable reel storage, retail racks, racking-supported mezzanines, and more.
The rivet structure offers high shear resistance, preventing stretching or cracking during the manufacturing of beam connectors. The load on the upright holes in the rivet beam connector is applied vertically downward. The material is shaped into a hook and punched to create the stamped beam connector. This design is capable of meeting standard temperature requirements.
In a cold storage environment, the weight of the load must be carefully considered. Bolt connections between stamped beam connectors and upright holes result in bolt tension. The two beam connectors on a beam are identical, allowing the beam to be mounted upright or rotated 180 degrees vertically without altering the welding position; it simply needs to be turned 180 degrees. This flexibility accommodates either the bottom or upper beam needs. However, because stamped beam connectors are hung in one direction, customers needing both bottom and upper beams will require at least two types of beams. This requirement can complicate installation and make it less convenient.
Rivet beam connectors can be made from various materials based on specific requirements and are not constrained by workmanship. In cold storage environments, materials resistant to low temperatures can be used. The thickness of the material used for rivet beam connectors can be adjusted according to the load capacity requirements. However, the material limits the use of stamping beam connectors, as they are formed by stretching material into a hook shape with a punch. Therefore, only materials with strong tensile properties should be used. For example, SPHC material with a thickness of 3.5 mm or less is commonly employed.
Drive-in racks are designed for storing homogeneous products and can accommodate a large number of pallets for each SKU. This high-density storage method offers significant space efficiency and maximizes volume storage, similar to block stacking, while providing easy access to pallets. The system consists of a series of racking units that create internal loading aisles with pallet support rails. Forklift trucks enter these inner aisles with their loads elevated above the level where they will be placed. Support rails are positioned on both sides of each loading aisle, allowing pallets to be stacked on different levels. Constructed from exceptionally durable materials, drive-in racks are suitable for storing fully laden pallets.
Drive-in racks are designed to store homogeneous products and accommodate a large number of pallets, making them an effective solution for maximizing storage space. They offer efficient use of warehouse space and generally support loading capacities ranging from 500 kg to 1500 kg per pallet. Drive-in storage racks utilize the FILO (First In, Last Out) or FIFO (First In, First Out) load management systems. Adjustable rails enhance space efficiency and make the racks straightforward to assemble.
The number of SKUs that a drive-in system can accommodate is equal to the number of loading aisles available. The depth and height of these aisles will determine how many pallets can be stored. To minimize additional pallet handling, it is recommended to store merchandise with the same SKU in each loading aisle. The depth of each aisle is influenced by factors such as the number of pallets per SKU, available space, and the anticipated storage duration. The frames of drive-in racks feature slots every 75 mm to accommodate beams and supports. The overall depth of the frame is determined by the dimensions of the storage aisles, as well as the height, measurements, and weight of the pallets being stored.
Storage racks can feature either single or double arms. Single arms are mounted on the left or right side of the racks, while double arms are placed in the middle. For beam connections, raw steel is tested by an independent third-party agency to ensure quality and safety. These racks often include a three-hooker design, which supports high load capacities and effectively dissipates the beam load vertically down the front face of the upright. Each beam connector is equipped with five safety pins to enhance protection and prevent the beam from dislodging during use.
Support rails in drive-in racks are stamped and can be adjusted in length. These rails are designed without connectors to ensure consistent load distribution. Advantages of drive-in racks include their capacity for heavy-duty loading and the ability to consistently center pallet loads thanks to the rail profiles. Additionally, top beams and top bracings enhance the overall integrity and stability of the racking system.
The Pallet Shuttle Rack System is a compact storage solution where an electric motor-driven shuttle operates on rails within storage channels, eliminating the need for forklifts to access the lanes. This system improves storage efficiency by allowing items to be grouped by channel rather than occupying full lanes. It enhances space utilization in depth, reduces the risk of accidents and rack damage, streamlines operator movements, and brings greater modernization and flexibility to warehouse operations. This system is particularly advantageous for organizations with high volumes of pallets per item and frequent loading and unloading needs.
In a Pallet Shuttle Rack System, the setup includes supporting racks, shuttle rails, and a shuttle cart. The shuttle cart, driven by an electric motor, rides on tracks and is operated via a hand-held remote control. A forklift is responsible for placing the shuttle cart into the designated lane. This system effectively optimizes space utilization and operational efficiency by reducing the need for forklifts to navigate within storage lanes.
Pallet shuttle racks offer significant flexibility, allowing each channel to accommodate different types of items. This system enhances productivity by improving the flow of incoming and outgoing items. With lower running, maintenance, and incident costs, pallet shuttle racks are highly cost-effective. They are also suitable for cold storage environments, making them ideal for warehouses with low temperature requirements, as they maximize storage capacity while reducing maneuvering time.
Double deep pallet racks can accommodate two pallets deep in a single-entrance configuration or four pallets deep in a double-entry setup, allowing for efficient shipping of large single-SKU orders. By reducing the number of aisles and increasing storage capacity, double deep racks enhance storage density. This system is ideal for products that require multiple pallets per SKU, though direct access is limited to the front pallets. Using this setup typically requires lifting equipment with double-depth telescopic forks.
The design of a double deep pallet rack mirrors that of a standard selective pallet rack; while the layout differs, the components are the same. The switch from selective racking to double deep racks boosts storage density by altering the aisle-to-rack ratio. With effective stock rotation, around 50 percent of pallets are immediately accessible, and the system typically utilizes over 90% of available storage space. The reach truck can maneuver under the bottom beam since it is elevated from the ground. This approach is particularly effective for managing SKUs with multiple pallets.
The Very Narrow Aisle (VNA) rack system, as its name suggests, maximizes floor space and vertical height. Designed for use in exceptionally narrow aisles (ranging from 1,500 to 2,000mm), this racking system significantly increases storage capacity by optimizing available space and expanding storage area. Each pallet can be accessed directly, and specialized forklift trucks are required to operate within the VNA rack system.
The mast of the forklift head can move left or right as necessary, and forklifts with elevating operator cabins are also compatible with the system, enabling manual picking. For narrow aisle systems to function effectively, very flat floors, closely aligned racking, uniformly sized pallets, and precise stock locating systems are essential. Successful implementation requires careful design interaction among all system components and the use of floor guides in the aisles.
In narrow aisle racks, the extremely narrow aisles enhance storage density while allowing direct access to every stored pallet. Free-roaming trucks on the floor provide flexibility in multi-aisle environments. Specialized equipment is employed to create high-speed throughput, and meticulous material handling practices ensure a safe and damage-free operation. A robust, highly level floor is essential to support the weight of large loads.
Longspan shelving is designed for the manual storage of medium and small products. This versatile racking system accommodates a variety of unit loads and provides direct access to all items. Its basic framework can be easily customized with various accessories to meet specific organizational needs, such as textile solutions.
Carton Flow Rack Systems offer a high-density storage solution for cartons and small unit loads, optimizing space and enhancing stock control. Designed with a gentle gradient, these racks feature rollers or wheels that enable lightweight unit loads to glide smoothly from the back to the front of the rack. Also known as flow-through racks, they use metal shelves with integrated rollers or wheels, making them ideal for efficient small-quantity case picking.
The pallet flow rack system operates on a similar principle to carton flow racks but on a larger scale. It uses conveyor wheel shelves to enable back-loaded pallets to move by gravity toward the front or pick face. This system is ideal for first-in/first-out (FIFO) inventory management. Additionally, the push back rack system employs wheels within the rack structure, allowing palletized items to be stored by pushing them up a gently inclined ramp.
This chapter will cover the applications and benefits of various storage racks, as well as their maintenance practices.
Rack systems are utilized across nearly every industry to create organized storage areas for products and materials. Examples include:
Warehouse racks often support heavy loads and, despite their robust design, can be prone to damage or failure. Regular inspection and maintenance are crucial to prevent potential accidents. This not only helps avoid damage to products but also ensures the safety of operators and prevents mishaps.
Industrial pallet rack maintenance, as outlined by the Rack Manufacturers Institute (RMI), might seem straightforward to an observer, but operators understand the complexity involved. The beam and column structure supporting stacked pallets may look simple, but even a slight additional bending load can jeopardize the entire system's stability. Therefore, regular inspection and maintenance of pallet racks are essential. It is crucial to perform these tasks correctly and professionally to ensure safety and structural integrity.
This article outlines the importance of inspecting and maintaining your pallet rack system and provides guidance on how to carry out these tasks effectively.
Pallet rack inspections are essential for protecting both materials and personnel and for ensuring compliance with OSHA regulations. Warehouse safety protocols encompass proper ventilation, adequate aisle space, clear flooring, prevention of slippery surfaces, and overall cleanliness. Therefore, industrial warehouses must be regularly inspected to maintain acceptable working conditions and safeguard the safety of operators.
The inspection of pallet racks is divided into two steps:
Maintaining pallet racks is crucial for extending their lifespan. These racks often endure uneven and excessive loads, making them susceptible to damage. To prevent or address damage, it's important to adhere to the RMI guidelines for assessing and repairing broken racks. Additionally, any rack repairs should be conducted under the supervision of a qualified expert, in accordance with RMI standards, to ensure safety and effectiveness.
The initial stage in pallet rack maintenance should be a thorough inspection. Once the inspection is completed, necessary repairs can be made to keep the warehouse rack system in good working order. For routine maintenance, ensure that any overloading situations are addressed by restocking commodities to avoid excessive stress on the racks. Pallets should be stacked evenly to minimize stress on the joints, and vertical stacking is often preferable to reduce beam bending stress compared to horizontal stacking. Additionally, replace any broken base plates and bolts to maintain long-term viability. It's crucial to keep aisles clear and enforce forklift speed limits to reduce the risk of accidents. Regular cleaning, rustproofing, and disinfection are also essential to maintain the system's condition and functionality.
Storage racks, also known as racking systems, are structures designed to store items and materials. They typically consist of at least two vertical frames, horizontal beams, and some form of decking, which may include bars, panels, or meshes. When selecting a storage racking system, it is important to consider the various types, their benefits and limitations, and their specific applications to make an informed decision.
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