How Pick Modules Increase Efficiency and Density in Distribution

Pick module systems are advanced engineered material handling systems that combine several storage and handling solutions, such as racking, conveyors, and mezzanines. These solutions are chosen and arranged by gaining an in-depth understanding of the characteristics and objectives of a distribution center. The goal of a pick module is to facilitate the swift movement of products, thereby speeding up the order fulfillment process.

A pick module is tailored to maximize the efficiency of handling multiple orders simultaneously. It accomplishes this by condensing and organizing products so that all steps within the order fulfillment process flow seamlessly and as quickly as possible. This can be achieved in several ways, including:

• Stacking storage and picking areas vertically via a multilevel system
• Incorporating automated systems such as conveyors
• Combining multiple types of material handling solutions tailored to diverse inventory needs
• Most importantly, creating a layout that allows all solutions to support each other in expediting the flow of orders

REB Storage Systems International offers full project management services for pick modules. Our team is highly knowledgeable in all areas of racking and automation options and will make sure your pick module system is the best fit for your SKU profiles, space, picking processes, and growth projections. We work with you to provide a turnkey system. From design, products procurement, subcontractor management, install, and permitting support, REB handles it all for you.

We’ve put together this article to help you better understand how you can utilize a pick module in your operation. By reading this article you’ll learn typical uses of a pick module, commonly integrated components, and how these components can be combined into an efficient layout. To contact the professionals at REB for further assistance, fill out our form or call us at (800) 252-5955.

How can a Pick Module Benefit a Distribution Center?

Because of the multifaceted and tailored approach to designing and building a pick module, they provide benefit for the distribution process in several ways at once. They support each individual process while also working together to benefit the operation as a whole.

Examples of how pick modules can benefit a distribution center include:

• Reduction of travel distances for pickers by condensing and organizing products and picking. In some cases, traveling is eliminated by incorporating conveyors.
• Increase of safety by creating an organized operation that keeps pickers out of the path of warehouse vehicles.
• Reduction of pick times by placing items in proximity with others that are typically picked together. For example, a vertical lift module can be incorporated to drastically increase the speed of kitting small parts.
• Support of one or more types of inventory rotation, including first-in, first-out (FIFO) and last-in, first out (LIFO).
• Support of one or more types of inventory storage, including full pallets, cartons, and small parts.
• Support of one or more types of order picking processes, such as batch picking and zone picking.

Components of Pick Module Systems

Pick module systems vary in complexity from single-level manual picking setups to sophisticated multi-tiered automated systems. By integrating these systems into a distribution center, space is efficiently utilized, pick rates are increased, and significant reductions in labor costs are achieved by minimizing the distance that workers travel. Read below to learn about common components included in a pick module system.

Racking

Racking is often the backbone of a pick module. There are several types of racking, each that is ideal for certain types of inventory and flow requirements. Therefore, strategic placement of different types of racking within a pick module is beneficial.

Selective Rack

Selective rack is the most used type of rack in a distribution center. Its versatility is one reason for this. An example of its versatility is its capability to customize bay sizes to accommodate ranges of SKU sizes. This can even be accomplished within the same row. For example, the lower bays of a row of selective can be small for piece picking, while the upper bays of that same row can be larger for pallet storage.

Bays can be customized to store odd shaped products, such as large and bulky products as well as long, flat items. For instance, the photo below shows selective rack with tight beam spacing to store sheet metal. This case study demonstrates several selective rack configurations designed to store 13,000 SKUs that range significantly in size and shape.

In addition, there are options regarding the overall layout of a selective rack system. One such option is designing the layout with very narrow aisles (VNAs). This will allow for higher density but requires special lift equipment. Another option is to design it as a double deep selective system. This will also allow for higher density than standard selective, but some selectivity is sacrificed.

Because of its high selectivity and flexibility, selective rack has many applications within a pick module. For example, it is often used within a pick module layout to store the overflow of palletized products, often referred to as reserve storage. However, it can also be used in conjunction with bins for handpicking. In this way, it can be a standalone system or integrated within a catwalk system. It can also be integrated above carton flow rack for replenishment of the carton flow rack.

Push Back Rack and Pallet Flow Rack

Push back rack and pallet flow rack are gravity flow options that provide high density pallet storage. Because of the combination of high selectivity and high density that these provide, they are often used within a pick module to store pallets of items for replenishment to picking areas. They can be used as standalone systems, integrated in upper catwalk levels, or integrated with other rack types in a one-level system. For example, the photo below demonstrates pallet flow rack integrated with selective and carton flow.

Additionally, pallet flow and push back are a great option for organizing SKUs within a pick module layout. This is accomplished by storing one SKU per lane, which makes locating and picking these products more efficient.

An important distinction between pallet flow and push back is that pallet flow is a first-in, first-out (FIFO) product flow option, while push back is a last-in, first-out (LIFO) option. Therefore, if you store products that are date sensitive, you’ll want to use pallet flow instead of push back. This article further explains differences between push back rack and pallet flow rack.

Carton Flow Rack

As the name suggests, carton flow rack is used to store cartons or bins of items. It is typically used within a pick module system for hand picking. Because it is a gravity flow system, the inclined shelves allow higher visibility and accessibility for hand picking than selective rack. Carton flow rack can be used as a standalone system, integrated in upper catwalk levels, or integrated with other rack types in a one-level system, as shown in the previous photo.

Drive-In Rack and Drive-Through Rack

Drive-in and drive-though rack is used as a standalone system within the layout of a pick module. These systems don’t use beams and eliminate the need for picking aisles. Instead, a lift truck drives into the rack and places pallets onto a support rail.

This layout makes it a highly dense system. However, selectivity is sacrificed with this system, since products are essentially stored as one cube. These features make drive-in and drive-though rack systems ideal for high-density storage of one SKU. In a pick module, this often means storing pallets of overflow items in a reserve storage area, or storing products that require large, one time moves of many or all the pallets.

Cantilever Rack

For company’s that store long items, such as lumber, furniture, and plumbing, cantilever rack can be ideal. Cantilever rack systems offer higher selectivity of these items as compared to selective rack. Cantilever rack can be integrated into the overall pick module layout as a standalone system in conjunction with other types of racking, such as with selective rack as shown in the below photo.

Mezzanines or Catwalks

To make full use of the vertical space available in distribution centers, mezzanines or catwalks are often integrated to construct a multilevel pick module system. Multilevel systems integrate pallet rack with decking, bar grating, stairs, and other components. These combine to create storage bays and picking aisles on upper levels.

Catwalks and mezzanines allow picking operations to occur on each level. They include a vertical transport system so that pickers can remain on their level while still receiving products and directing products down to the floor for the next step in the distribution process.

Vertical Transport Systems

Vertical transport systems are necessary in multilevel pick modules to swiftly get products from upper levels down to the ground floor, and vice versa. There are several types of vertical transport systems. Which one is right for a pick module will depend on product types, picking and shipping practices, and budgetary requirements. Vertical transport systems include options that are powered systems and non-powered.

Powered vertical transport systems include:

• Spiral conveyors: Powered spiral conveyors can transport items to and from the upper levels of the pick module. Because of their vertical, spiraled design they maintain a smaller footprint than traditional inclined conveyors. The smooth transition provided by spiral conveyors make them ideal for transporting fragile items. Spiral conveyors can be integrated with accumulation functionality so that items can be held on the spiral conveyor if time is needed at the ground level or upper level to remove items.
• Inclined conveyors: Powered inclined conveyors use a motorized belt or rollers to transport items to or from the upper levels of a pick module. Powered inclined conveyors are typically equipped with gripping belts, cleats, or textured surfaces to prevent items from slipping, especially on steeper inclines. These conveyors are highly customizable to integrate smoothly with other conveyor lines, packing stations, or shipping areas.
• Continuous vertical conveyor: Continuous vertical conveyors (CVCs), also known as S-conveyors or box lifters, provide steady and constant movement of items to or from the upper levels of the pick module. CVCs use a looped conveyor belt or chain mechanism with platforms that travel in a steady, uninterrupted motion. This allows multiple items to be loaded, unloaded, and in-transit to unloading at the same time. Because multiple operations are happening simultaneously, CVCs provide high throughput of items.
• Vertical reciprocating conveyor: A vertical reciprocating conveyor (VRC) features a lift platform that moves up and down on a track, driven by hydraulic or mechanical systems to transport pallets or cartons to and from the upper levels of a pick module. They are customized to the product requirements, such as weight and dimensions. There are options for pallets or cartons to be loaded manually, such as by hand or by forklift, as well as to be loaded onto by a conveyor. For automated loading, it’s typically used in conjunction with an accumulation conveyor. For example, an accumulation conveyor can be used to transport products to the vertical transport conveyor, hold it at the entrance until the vertical transport conveyor becomes available, then load it on.

Vertical Reciprocating Conveyor

Non-powered vertical transport systems include:

• Gravity chutes: Gravity chutes are often designed as a spiral but can be designed as a straight decline. Because these chutes use gravity, they are used to transport items only from upper levels of the pick module to the floor level and cannot transport items to upper levels. Gravity chutes use a specialized coating, such as fiberglass, and precise pitch to ensure that products glide smoothly and safely to the ground floor.
• Pallet drop areas: Pallet drop areas are designated areas located at the edge of the platform on each level of the pick module. Pallets that must be put away on upper levels or brought down from upper levels to the ground floor are placed on these designated areas. A forklift moves these pallets to and from the pallet drop areas. Pallet drop areas include a safety pivot gate to ensure that employees can’t fall off the platform. They can also be used in conjunction with a gravity chute, so that pallet drop areas are used to bring products to upper levels while the gravity chute is used to bring them down.

Pallet Drop Area with Pivot Gate

Automated Material Handling Systems

Conveyors

Conveyors are hugely beneficial for efficiently transporting products throughout different sections of the pick module. Conveyors are versatile, there are options that cover many applications. Often, more than one type of conveyor is integrated into a pick module to accommodate different needs throughout the distribution process. Conveyor types that are frequently used include:

Accumulation conveyors: The unique characteristic of accumulation conveyors is that it will hold products in a queue at certain points to allow time for equipment or other material handling resources to become available down the line. Once these resources become available, the system gives a signal to release the next queue of products. Because the accumulation is custom programed, these conveyors accommodate the flow requirements specific to each operation. They are particularly useful for picking and packing operations and for operations that have varying throughput rates.

Sortation conveyors: Sortation conveyor systems are used to direct products from one conveyor line to another. These are complex systems that use scanners to identify each product coming down the conveyor line. Once scanned, the system recognizes which one of the multiple conveyor lines that product belongs on and subsequently diverts it to that conveyor. These conveyors are highly customizable. They can be programmed to sort by size, SKU type, and distribution destination, among others. They are typically used in operations with high throughput.

Transportation conveyors: Unlike sortation and accumulation conveyors, transportation conveyors don’t distinguish between different products or environmental factors. Instead, they continuously take products from point A to point B as they are placed on the conveyor. These conveyors range from live roller and belt conveyors to non-electrical options such as gravity conveyors. Because they include a variety of options and price points, transportation conveyors are the most common type of conveyor seen in distribution centers.

Vertical Lift Modules (VLM)

A vertical lift module, commonly referred to as a VLM, is an enclosed system of vertically arranged trays stored in both the front and rear of the unit with an extractor device operating in the center. Vertical lift modules automatically deliver trays with stored items to an access window. To retrieve each item, the picker simply provides the VLM information by selecting it on a touchscreen, scanning a barcode, or importing a list from an ERP.

This system decreases pick times versus traditional racking by eliminating the need for the picker to travel and locate each item. In addition to decreased travel times for pickers, VLMs can expedite the kitting and batch picking processes within a pick module. This is accomplished by storing kitted or batch items on the same tray.

Increased density is also achieved with a VLM in comparison to traditional selective pallet rack. Because items are stored vertically and trays are condensed within the VLM unit, floor space required for stored items is significantly reduced. In one case study, the VLM saved a company 75% of floor space compared to the racking they were using.

Pallet Shuttle

Pallet shuttles, also known as pallet runners, are a semiautomated solution for pallet storage. Pallet shuttles consist of racking and automated carts. Each aisle has a cart, and these carts transport pallets to and from their designated location within that row of the rack system.

Pallets are loaded and unloaded by a forklift. Because the pallets are brought to the picking aisle for the forklift, pallet shuttles eliminate the need for picking aisles between each row of rack. This makes a pallet shuttle system exceptionally dense compared to a traditional rack system. This also shortens pick times. This increased density and high throughput is seen when a pallet shuttle is integrated with a pick module versus integrating standard pallet racking. Click here to read a case study that compares pallet shuttles with selective and pallet flow rack.

Outside of standard storage and retrieval, a pallet shuttle can be used to improve the storage of specialty items that require gentle transport. Examples include products that are non-stackable and products that must be displayed in certain ways on pallets.

Additionally, pallet shuttles improve specific operations within a pick module, such as staging pallets for shipping. For example, the night shift can stage each lane with all pallets that need to be loaded onto each truck the next day. Thus, the day shift can quickly unload the already built load from a lane to be loaded onto the corresponding truck.

Lighted Picking Systems

Lighted picking systems, which include pick-to-light and put-to-light, are lighted displays that are attached to the pick face of each pick location. When used for picking, these displays are programmed to indicate to the picker where their next pick takes place, often by changing color. Once the picker goes to that location, the lighted display shows them how many of that SKU to pick. Once picked, the picker presses a button to indicate completion, which triggers the next item’s lighted display to activate.

When used for packing, a put wall can be integrated into a pick module. For example, items can be picked via totes, which are then brought to the put wall. The operator scans the tote, at which time the put wall will light up each cube that requires that product, displaying the amount needed.

Lighted picking systems are a cost effective way to drastically reduce pick errors, decrease pick times, and increase throughput. This is because the hardware and labor costs to install the lighted pick displays are low compared to other types of automation. They can be mounted to any existing or new racking or shelving.

Shelving

Industrial shelving, such as rivet shelving and steel shelving, is a cost-effective way to provide storage for applications that don’t require heavier duty racking. Typically, it’s used within a pick module for handpicking unpalletized products from cartons. However, it can be used on a larger scale, such as supporting a multilevel pick module.

Safety Componentry

Safety componentry is often an afterthought but is a hugely important part of a pick module system. This is especially true for a multilevel system where employees are navigating high levels of the system. Safety components often used in a pick module include:

• Guardrails: To provide a barrier to unsafe areas, such as at drop-offs.
• Handrails: To assist employees in traveling safely on stairs.
• Kickplates: Installed on the floor of each drop-off to prevent items from sliding off the upper levels of the system and causing a risk to employees on the ground level.
• Safety netting: To prevent items from falling off the upper levels of a system and causing a risk to employees on the ground level.
• Rack column protectors: Installed on each rack column that is in the path of forklifts to reduce damage in the event of a forklift impact.
• Down aisle protectors: Installed on the floor of picking aisles along the base of the rack system to deter forklifts from hitting the rack.
• Safety gates: Used to prevent employees from falling from access points on the upper levels of the pick module, such as pallet drop areas.

Examples of Custom Pick Modules Provided by REB

Pick modules are highly customizable and therefore configurations range widely. The layout and components for each pick module are determined by many factors such as SKU characteristics, picking practices, building layout, growth projections, and distribution efficiency goals.

Read below to view several pick module layout examples. We’ve included the company’s obstacles, objectives, and pick module solutions for each so that you can get an idea of what may work for your operation. To speak with one of our material handling experts to gain an understanding of what will work for your operation, call (800) 252-5955 or fill out the form on this page.

Pick Module Case Study 1

This case study is a great example of a company expanding their pick module over several years as needs arise. In 2011, the company, who is an auto parts distributor, purchased a new distribution center. Their products range significantly from large, palletized items to small, handpicked items. The pick module needed to optimize for the required selectivity, density, and picking practices of each type of inventory while promoting the overall efficient flow of the distribution operation.

Therefore, the following solutions were implemented:

• Selective rack with 60” very narrow aisles for pallet storage. Heavy duty selective rack was also incorporated for storage of heavier products. This system has a tight beam spacing of 1-ft.
• Push back rack for high-density pallet storage. This system is 6-pallets deep. Each lane is dedicated to 1 SKU, making picking products in bulk faster.
• Rivet shelving with 48” very narrow aisles for hand picking of products in cartons. Due to these very narrow aisles, to utilize the full height of the building the company would have had to switch their picking operation to include a special lift truck, called a Joey. Due to this, the company decided they would only use 144” of their 264” vertical space. This allowed them to continue using rolling ladders for picking.

Because the company knew they would need more storage and efficiency as they grew, the plans for this pick module included vertical expansion of the rivet shelving as well as the addition of a conveyor system. This allowed them to stay within their budget while planning for the full utilization of their space.

Ten years later, the company decided it was time to proceed with that expansion. They chose to splice their existing rivet shelving to add 9 additional shelves, increasing the height of the rivet shelving system from 144” to 264”.

Additionally, they added a conveyor system that includes two conveyor types: a belt driven live roller conveyor and an extendable power conveyor. These are used for efficient packing of items and transport onto trucks. The conveyor line also integrates 16 packing stations located in regular intervals throughout the conveyor.

See below for a video overview of this project. To view the full case study, click here.

Pick Module Case Study 2

A pool supplies distributor was relocating its distribution center to a larger building. REB reviewed a list of the company’s SKU characteristics, turnover rates, picking methods, and growth projections. Each of these items was evaluated to develop a solution that optimizes the flow of orders. This evaluation produced the following:

• Products were not being replenished fast enough for pickers, creating bottlenecks in the distribution process.
• The company uses forklifts to transport pallets.
• Because of rapid product turnover, excess pallets of products need to be stored in the facility to replenish the cases for picking.
• The company predicted substantial growth over the next five years. However, their budget only allowed them to address their immediate needs.

Based on this information, REB developed a pick module that includes a forward pick area and a reserve (static) storage area. The forward pick area is the rapid picking part of the pick module and integrates pallet flow rack, carton flow rack, and selective rack to facilitate the swift and continuous flow of products. See below the layout of the pick module as well as the elevation view of the forward pick system.

Because the company predicted growth, REB designed the pick module to allow for a catwalk level to be added. This gives the company room to grow with their existing material handling system while staying within their current budget.

See below for a video overview of this project. To view the full case study, click here.

Pick Module Case Study 3

A playground equipment supplier was operating out of three buildings: their main warehouse, which was used for shipping and receiving orders, their out-building, which was used to store all their overflow inventory, and their office building. Having to transport their inventory between the two warehouses was inconvenient and time consuming. This led them to purchase a new distribution center with the goal of consolidating all their operations. Therefore, they required a pick module that accommodated all inventory and distribution procedures into this space.

REB analyzed the company’s SKU characteristics, turnover rates, picking methods, and growth projections. Each of these items was evaluated to develop a solution that optimizes the flow of orders. This evaluation produced the following:

• The company’s main goal was to increase efficiency. This was somewhat accomplished by consolidating their operation into one building, however the new pick module had to optimize efficiency and storage in their new space.
• Their inventory ranges significantly from small parts to extremely large and oddly shaped products.
• They kit small parts used to install and decorate the playground equipment, such as bolts, brackets, and visual accessories.
• Some of their inventory is too large to fit on racking. These items are stored on carts so that they are easily transported. However, their layout required the carts to be kept within the aisles of the warehouse. Consequently, they were often in the way of pickers and had to be moved around, causing major inefficiencies.
• Certain pieces of inventory that the company stores are kept in gaylords, which are containers attached to pallets.
• Some of the company’s products would benefit from a first-in, first-out (FIFO) inventory rotation.

Based on this information, REB developed a pick module that includes selective racking, pallet flow racking, gravity flow racking, and vertical lift modules.

• Vertical lift modules: Semi-automated solution to store their small pieces of inventory, such as brackets, bolts, and playground accessories. This drastically reduced their footprint for storage of these items. For the company to store their small parts on shelving it would require 1,600 sqft of shelving space. With the VLMs, the same products are stored in an area of only 395 sqft. Additionally, it decreased their kitting time by supplying items in the same kit on the same tray.

• Selective rack: REB designed a selective racking system of 680 bays made up of 7 different bay sizes tailored to their product range. The bay sizes range from 30” deep, for small parts storage, to 168” deep, for large playground items. For storage of their large items stored on carts, REB’s design includes a section of 6-deep selective rack with an egress aisle, which provides a designated area for the carts to be parked in.
• Push back rack: For the products storage in gaylords it was determined that 6-deep push back rack best suited this inventory, since it stores higher counts of each of these SKUs in a high-density manner.
• Pallet flow rack: Because some of the company’s inventory benefits from first-in, first-out (FIFO) inventory rotation, REB integrated a 6-deep pallet flow system with 744 pallet positions.

See below for a video overview of this project. To view the full case study, click here.

Pick Module Case Study 4

An auto parts dealer was expanding rapidly. However, their throughput was not keeping up with demand, causing them to fall behind on orders. Their building did not support expansion and so they secured a new, larger facility.

REB analyzed the company’s SKU characteristics, turnover rates, picking methods, and growth projections. Each of these items was evaluated to develop a solution that optimizes the flow of orders. This evaluation produced the following:

• The company has three fulfillment categories: e-commerce orders, local deliveries, and distributor orders. However, there were not well-organized processes for these orders to be picked, packed, and shipped, leaving room for efficiency.
• The company wanted to use automation to expedite the order fulfillment process.
• E-commerce and local orders are typically picked from cartons. Pickers pick these items into totes, which then go to the shipping area for packing and shipment.
• The company stores some specialty items such as chemicals, aerosols, and batteries.
• The company stores long, flat products such as sheet metal.

Based on this information, REB developed a pick module that includes the following:

For high-density piece picking a ground plus two-level catwalk system was included. This allows the company to utilize their vertical space, significantly reducing the storage footprint of these items and allowing pickers to pick on multiple levels of the system. Two different bay sizes are included in the catwalk system to accommodate various sized inventory. Additionally, two vertical lift modules (VRCs) are integrated into the catwalk system. These transport pallets of products to upper levels of the catwalk system to replenish picking areas.

To move products efficiently from upper levels of the catwalk system to the ground level for packing and shipping, a multifunctional conveyor system consisting of five conveyor types is integrated with the catwalk system. These conveyors work together to bring products from the upper levels down to the ground via a tote lift conveyor. Once on the ground level, a sortation conveyor scans each tote and automatically sends them to one of four points: 1) first floor pick requirement, 2) e-commerce orders, 3) local deliveries, and 4) distributor orders.

Packing stations were included at each of the shipping endpoints (e-commerce, local, and distributor). To control the flow of orders for packers, an accumulation conveyor is integrated leading up to the packing stations. This allows totes to accumulate until the packer indicates to the system by pressing a button to send the next tote in the queue.

Because the company stores specialty items such as chemicals, aerosols, and batteries, a selective rack system separate from the catwalk system was included. Due to the nature of these items, lockable wire mesh enclosures were attached to the rack in several places. Additionally, a selective rack system with tight beam spacing of 16” was included for storage of long, flat items.

This system working together drastically increased the company’s throughput on their orders. See below for a video overview of this project.

REB Pick Modules Customized for Your Operation

REB Storage Systems International designs and builds custom pick modules to fit the unique requirements of an operation. Our single-level and multilevel pick modules can include a variety of components such as racking, automation, and shelving. By partnering with top manufacturers, REB provides turnkey material handling solutions tailored to the unique needs of any distribution center.

By employing these sophisticated systems, distribution centers can expect not only to enhance their operational efficiency but also to achieve faster order processing times, thereby improving overall productivity and customer satisfaction.

To learn more about REB Storage Systems pick module systems, fill in the contact form on this page or call (800) 252-5955 to schedule an appointment with one of our specialists who can discuss pick module applications for your distribution center.