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Palletizers: Types, Functions and Parts

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Introduction

This article provides comprehensive knowledge about palletizers. Read further and learn about:

  • What is a palletizer and how does it work?
  • History
  • Conventional Palletizers
  • Robotic Palletizers
  • Hybrid Palletizers
  • And much more...
Low Level Palletizer
Image Provided by: TopTier

Chapter 1: What is a Palletizer and How Does It Work?

A palletizer is a mechanical system used to stack and organize various products into one cohesive load, thus improving efficiency in handling, storage, and transportation. Often, it is part of a larger packaging operation, which might include functions like weighing, counting, sorting, labeling, metal detection, and wrapping. These additional processes can sometimes be included within the palletizer or handled with different equipment.

Palletized products form a unit load by bundling materials for streamlined handling. It is generally quicker and more economical to move a single large unit rather than numerous smaller items. Typically, finished goods aren't made for individual shipping but are placed in boxes, cases, trays, or crates, then consolidated into a single load supported by pallets or roll cages. The packaging forms represent secondary unit loads, with roll cages identified as tertiary unit loads.

Unit Load

The palletizer arranges products onto a pallet, hence the term. Pallets are level, sturdy platforms crafted from wood, plastic, paper, or metal featuring notches or openings. These features accommodate forklifts and hand pallet trucks for lifting and relocating the load. These openings designate a pallet as either two-way or four-way, indicating forklift entry directions. Most pallets can support loads up to one metric ton over an area close to one square meter. Below are examples of standard pallet dimensions.

Dimensions
(W x L) in millimeters
Dimensions
(W x L) in inches
Unused Floor Space
(ISO Container)
Region
1016 x 1219 40.0 x 48.00 3.7% North America
1000 x 1200 39.37 x 47.24 6.7% Europe, Asia
1165 x 1165 45.9 x 45.9 8.1% Australia
1067 x 1067 42.00 x 42.00 11.5% North America, Europe, Asia
1100 x 1100 43.30 x 43.30 14% Asia
800 x 1200 31.50 x 47.24 15.2% Europe
Different Pallet Designs

Some palletizers are equipped to stack products using slip sheets or conveyor surfaces and are called unitizers. These unitized loads eliminate the need for a pallet. In some instances, "palletizers" and "unitizers" are interchangeably used terms.

Types of Pallets

There are three main types of pallets made from wood or plastic, and one type made from cardboard.

The most prevalent is the GMA pallet, typically measuring 40x48 inches, with notches on the sides facilitating side lifting access.

The CHEP pallet ranks as the second most used. This design, also usually sized 40x48 inches, incorporates blocks on every side, making handling possible from any direction. These pallets are easily recognized by their distinctive blue color.

PECO pallets are emerging in the industry, providing similar services as CHEP. They are known for their red paint identifiers.

The Pull Board is characterized by a corrugated sheet with dual 3-inch tabs generally located on adjacent sides. Forklifts equipped with special attachments can use these tabs to push or pull loads on or off the prongs. Pull Boards are favored for their hygiene benefits and space efficiency, allowing up to an additional 5 inches of space per load, potentially saving significant costs by accommodating additional layers in a transport vehicle.

Certain palletizers are engineered to stack items on slip sheets or conveying surfaces, termed unitizers. With unitized loads, there's no requirement for a pallet, and in some applications, the terms "palletizers" and "unitizers" are used interchangeably.

Diverse companies may demand various pallet arrangements tailored to their specific requirements.

  • Companies might apply tier sheets or unconventional configurations to maintain load stability, especially during manual transport of palletized loads to a stretch wrapper using fork trucks.
  • Pallet movement in automated systems is exceptionally smooth, allowing pattern simplification to optimize pallet utilization.
  • Improved pallet utilization can yield considerable savings throughout a company's supply chain encompassing transportation and warehousing.
  • Simplifying palletizing methods helps customers achieve elevated speeds and greater operational efficiencies.

Pallet Patterns

This stacking arrangement strengthens load integrity with a foundational column that bolsters the whole pile. In warehouses, pallets can be stacked up to four units high, leveraging load strength from the vertically aligned box corners. The top interlocked section adds further stability, ensuring unwrapped loads can be safely maneuvered with a forklift to a wrapping station.

Chapter 2: What is the history of palletizers?

Before the advent of automatic palletizing systems, warehouses and distribution centers relied heavily on manual hand stacking to organize products into pallet loads for storage and shipping. This method of manual palletizing was extremely labor-intensive and time-consuming, with workers expending considerable physical effort to achieve relatively low throughput. As global commerce expanded and supply chain efficiency became a top priority, the need for optimized material handling solutions became increasingly apparent. The adoption of pallets and pallet handling equipment revolutionized logistics in the early 20th century, particularly during World War II, when rapid and reliable transport of heavy loads became critical for military and industrial supply chains.

The introduction of the first mechanical palletizer by Lamson Corp. in 1948 marked a major milestone in warehouse automation technology. This early row-forming palletizer was designed to automate the process of arranging products—such as cases, cartons, bags, or boxes—into rows. These rows were then systematically transferred to a stacking area, where each new layer was placed upon the previous one until a complete pallet load was constructed. Compared to manual operations, this innovation greatly increased both throughput and consistency, setting the stage for future advancements in automated palletizing equipment and machinery.

With the rise of high-speed production and distribution demands in the 1970s, the material handling industry introduced the in-line palletizer. Unlike traditional row-forming palletizers that relied on intermittent movement, in-line palletizers utilized continuous product flow technology. This enabled the precise orientation and positioning of products onto layer-forming platforms, significantly boosting line efficiency and reducing bottlenecks. In-line palletizers are especially valued in industries such as food and beverage, consumer packaged goods, and manufacturing, where rapid end-of-line automation is essential for scalable operations.

The 1980s brought further innovation with the development of robotic palletizers, a major leap forward in automation and versatility. These advanced palletizing robots employ articulating arms equipped with end-of-arm tooling (EOAT)—such as mechanical grippers, vacuum suction grippers, or magnetic devices—tailored to handle a diverse array of packaging types and product sizes. Robotic palletizing systems facilitate flexible operation, fast changeovers, and precise stacking patterns, making them ideal for environments with high product variability or custom palletizing requirements. The widespread adoption of robotic and automated palletizing solutions has since transformed modern warehouses, distribution centers, and manufacturing facilities, leading to greater productivity, improved worker safety, and enhanced supply chain optimization.

Today, the evolution of palletizer technology continues with the integration of smart sensors, machine learning algorithms, and cloud-based warehouse management systems. Advanced automatic palletizers and robotic palletizing solutions now offer real-time data tracking, predictive maintenance, and seamless connectivity with upstream and downstream automation for enhanced operational efficiency. As e-commerce, just-in-time delivery, and global trade accelerate, investing in state-of-the-art palletizing systems is increasingly essential for businesses aiming to minimize costs, reduce manual labor, and stay competitive in the rapidly evolving materials handling industry.

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    Chapter 3: What are the types of conventional palletizers?

    Palletizers are mainly divided into two categories: conventional and robotic palletizers. Both can receive products at high and low elevations. High elevations typically range between 84" to 124", while low elevations are 30" to 36". Conventional palletizers are then divided into floor- (low-) level and high-level palletizers.

    Floor-level Palletizers

    These palletizers typically have an infeed level of 30" to 36". As products travel through the infeed conveyor, they are oriented by a turning device or conveyor before being moved to the row-forming area. Products are arranged into rows until a row is complete. This row is then transferred to the layer-forming area. Once a full layer is formed, it is pushed forward to the stripper plate, where the products are adjusted in height and placed onto the pallet or the previous layer. The stack remains stationary during the load-building process, which continues until the pallet is fully loaded. The finished pallet is then transferred to the discharge conveyor, usually set at an 18" discharge level.

    Low Entry Palletizer

    Floor-level palletizers are generally less expensive and simpler to construct compared to high-level palletizers, and they require less floor space. With most components positioned at floor level, maintenance is quicker and more straightforward due to easy access to the parts. Additionally, operators can easily monitor the machine’s operation since most moving parts are at eye level. When integrating with other equipment in the packaging line, floor-level palletizers are ideal because they do not require elevation changes for the infeed conveyor, making them well-suited for pairing with packers and sealers.

    High-level Palletizers

    High-level palletizers typically have an infeed level ranging from 84" to 124" or more. Like floor-level palletizers, products are transported by the infeed conveyor to a turning device or conveyor that rotates them into the correct orientation before moving them to the row-forming area. Products are arranged into rows until a row is complete, then transferred to the layer-forming area. Once a layer is formed, it is moved into position on the pallet or stack. The main distinction from floor-level palletizers is the ability of high-level palletizers to raise and lower the stack with each layer added. After the stack is completed, it is lowered onto the discharge conveyor, which is usually set between 18" to 30". In many installations, a raised operator platform is built alongside the machine for easier operation and monitoring.

    High-level palletizers are ideal when there is sufficient space for an inclined conveyor, allowing the packer and sealer to be positioned at a distance from the palletizer. Compared to floor-level palletizers, high-level machines offer higher throughput relative to their size, making floor space utilization more efficient. They are capable of handling throughputs of approximately 40 to 50 items per minute, regardless of the discharge elevation of the packer or sealer.

    Chapter 4: What are the parts of a conventional palletizer?

    A conventional palletizer consists of various components, including both static and moving parts. Some of these components may be integrated directly into the palletizer, while others can be installed as separate pieces of equipment.

    Knockdown Conveyor

    Bags exiting the packaging units and sewing machines are typically in an upright position. They are then positioned or flattened by the knockdown conveyor to prepare them for palletizing.

    Knockdown Conveyor

    Checkweigher

    This can be either an integrated or separate machine used to ensure the accuracy of the weights of bagged products prior to storage and distribution.

    Metal Detector

    Similar to the checkweigher, this device can be integrated with the palletizer or operate as a separate machine. The metal detector identifies any ferrous, non-ferrous, or stainless-steel contaminants in the product.

    Metal Detector

    Reject Conveyor

    Products that are detected as either being off-weight or containing metal contaminants are diverted by the reject conveyor to a staging area or platform.

    In-feed Conveyor

    Products can enter a palletizer from different sides, including the side, rear, or front. These infeed types apply to both floor-level and high-level palletizers.

    Bag Flattener

    To ensure the pattern is formed correctly, the bag flattener adjusts and shapes the bags to the proper height.

    Bag Flattener

    Turning Devices

    As products are fed onto the palletizing machine via the conveyor, they are oriented into the correct position before entering the row-forming area. Various turning devices are used for this purpose, including turn shoes, cushioned turns, turntables, and soft turn devices. Turn shoes and cushioned turns gently nudge the product to rotate it by 90°. Turntables lift and rotate products by +90°, -90°, or 180°. Soft turn devices utilize two sets of rollers driven by variable frequency drives (VFDs) to achieve rotations of +90°, -90°, or 180° by varying roller speeds.

    Heavy Duty Turntable

    Stops

    These mechanical devices are used to create the desired pattern in the row-forming area by establishing side-to-side gaps. Stops are activated by pneumatic valves and cylinders, which are controlled by programmable logic controllers (PLCs). To alter forming patterns, only software controls need to be adjusted, eliminating the need for hardware changes.

    Pusher Gate

    These mechanical devices, similar to stops, assist in pattern formation by creating front and back gaps. Once a layer is complete, it is transferred onto a stripper plate or apron, which then moves it onto the pallet. When the stripper plate is in place on top of the pallet or stack, a gate descends to block the layer's movement. The stripper plate is then retracted, leaving the layer in position on the stack. A pusher gate holds the layer in place until it is released.

    Bi-parting Stripper Apron

    This component enables the creation of front and back gaps without the need for a pusher gate. As the stripper apron opens in the middle, it forms gaps while the layer is placed onto the stack below.

    Empty Pallet Dispenser

    As the name suggests, this component dispenses and conveys pallets to ensure the continuous operation of the palletizer. When one unit load is completed, the pallet dispenser feeds a new pallet. Typically, a pallet dispenser holds 10 to 20 pallets in its pallet magazine.

    Empty Pallet Dispenser

    Slip Sheet Dispenser

    For some materials, such as bagged products, slip sheets are needed between layers. A slip sheet dispenser uses a venturi vacuum system to efficiently place these slip sheets.

    Slip Sheet Dispenser

    Finished Pallet Conveyor

    This component transfers completed unit loads onto a platform, where they can be picked up by forklifts or hand pallet trucks for storage.

    Control Panel

    This is the control area where operators troubleshoot, adjust, or reprogram the palletizer and its automated components. The main element of the control panel is the PLC, which controls circuit functions according to the machine’s programming.

    Chapter 5: What are the different types of robotic palletizers?

    These palletizers utilize robotic arms to maneuver the end effector and perform pattern formation. Robotic palletizers are categorized into Cartesian, gantry, SCARA, and articulated types. Each type varies in flexibility and range of movement.

    Cartesian Palletizer

    This type of palletizer has an end of arm tool that can move in three directions of space, or the Cartesian axes X, Y, and Z, hence the name Cartesian. Its mechanical structure consists of beams and a telescopic mast usually actuated by servo motors. This type of robotic palletizer is slow and is used for products with consistent weight and sizes. This is generally the cheapest type of robotic palletizer suiting single line speeds of up to 10 items per minute.

    Cartesian Palletizer

    Gantry Palletizer

    A gantry palletizer features an end effector assembly mounted on a beam that moves along one axis. The beam itself moves along a perpendicular axis, allowing for movement in the X-Y plane. To move vertically along the Z-axis, the end effector assembly uses a telescopic or articulated arm that can extend or retract. Gantry palletizers are often categorized as Cartesian palletizers due to their linear movement along Cartesian axes. While they perform pick-and-place operations, they are generally slower than Cartesian robots and tend to be larger and more expensive. However, they offer the advantage of lifting heavier loads.

    Gantry Palletizer

    Selective Compliant Articulated Robot Arm (SCARA)

    A SCARA robot features an arm that is flexible in the X-Y plane (left, right, forward, and backward) but rigid along the Z-axis (up and down). This "Selective Compliant" characteristic is what defines its name. The "Articulated Robot Arm" of a SCARA resembles a human arm, consisting of two linked segments connected by a joint, allowing for extension and folding. SCARA robots are faster than Cartesian palletizers and can handle multiple palletizing lines, operating at speeds of around 20 items per minute.

    SCARA Palletizer

    Articulated Palletizer

    This type of palletizer offers two additional degrees of freedom compared to SCARA palletizers. Articulated palletizers feature arms connected by a simple joint at one end, similar to SCARA models, but they lack a mast. Instead, one arm is mounted on a swivel joint with a fixed base, allowing for greater flexibility in movement. Articulated palletizers are faster than SCARAs and can handle multiple production lines, typically processing around 25 items per minute.

    Articulated Robot Palletizer

    Chapter 6: What are the parts of a robotic palletizer?

    Robotic palletizers vary in their approach to pattern formation and use distinct components based on their design. While elements such as check weighers and metal detectors are utilized, they are typically installed as separate pieces of equipment. Below are the common components of a robotic palletizer.

    Robotic Palletizing System

    Beams

    This component supports the end effector and allows linear movement along a single axis. Motion is provided by servo motors through mechanisms such as rollers and rails, rack and pinion gearing systems, or chain and sprocket drives. Beams are commonly found in Cartesian and gantry palletizers.

    Columns or Mast

    Mounted on a fixed base, this part supports the beam or arm and end effector assembly. It uses hydraulics, servo motors, or chain drives to enable vertical movement, allowing the connected components to move up and down.

    Arms

    Typically consisting of two linked segments, arms enable the end effector to move horizontally by rotating, extending, or folding.

    Joints

    These components provide rotational movement between various parts of the palletizer system. The number of joints can vary depending on the required versatility of the system.

    End Effectors

    Often referred to as end-of-arm tools, end effectors are crucial in robotic palletizer assemblies due to their versatility compared to conventional palletizers. They are responsible for picking up and placing products in the correct location and orientation on the stack. Designed to handle a variety of products with a single tool, they can also be equipped to retrieve pallets from a pallet rack or to pick slip sheets, tier sheets, or top caps from a dispensing rack. These features enhance the robot's functionality and efficiency.

    Following are the most common types of end effectors.

    Clamps

    Clamps lift products by gripping the sides, enabling the handling of multiple items with the same orientation simultaneously, which speeds up throughput. They are particularly useful for stable products or those not suited for vacuum handling, such as HSC (cases with no top) or display cases.

    Forks

    Fork tools are used for delicate, unstable, or special cases like HSC (cases with no top) or warm/hot shrink-wrapped products where gentle handling is necessary. The tool features cutouts that allow it to slide underneath the product for lifting and cradling. A clamp can be added to the fork tool for added stability during movement.

    Fingers

    Finger end effectors are mechanical tools that open and close in two directions, providing support underneath the product. They are commonly used for handling bags.

    Finger End Effector

    Vacuum

    Vacuum end effectors are commonly used for picking up RSC cases and can be configured to handle multiple cases simultaneously. They use a blower to generate a high volume of vacuum necessary to lift thin, porous corrugated boxes made from recycled materials. This approach is often preferred over venturi systems, which rely on plant air that may be unreliable or insufficient for the required air volume.

    Bags

    Bag end-of-arm tools are designed to pick up large bags of product one at a time. They can be equipped to add slip sheets or tier sheets between layers, depending on the speed requirements.

    Magnetic

    Magnetic end effectors use electromagnets to handle products and are typically employed for stacking and palletizing canned goods.

    Magnetic End Effector

    Chapter 7: What are the differences between conventional and robotic palletizing?

    While conventional palletizers represent the earlier generation of palletizing technology, they are not fully superseded by newer robotic models. Each type of palletizer offers distinct benefits tailored to specific applications. Given the wide variety of industries that utilize palletizers, no single design fits all needs. Below are the advantages of using conventional palletizers compared to robotic ones.

    Merits of Using Conventional Palletizers:

    Tolerance of Packaging Types

    Conventional palletizers build the unit load by turning and pushing products into their designated positions and orientations, eliminating the need to pick up and place each item. This method allows for flexibility in handling different packaging dimensions or types without affecting the palletizer's operation. Any necessary adjustments can be made through control program changes, without requiring hardware modifications.

    Palletizing Patterns

    Faster Complex Pattern Forming

    Robotic palletizers can be slow when operating by picking and placing individual products. To improve throughput, they often collect and handle multiple products simultaneously. However, this approach typically offers less flexibility compared to conventional palletizers, which can be easily adjusted to change pattern configurations without impacting throughput.

    Benefits of Robotic Palletizers:

    Robotic Material Handling

    Cost-Effective for Simple Applications

    For straightforward palletizing tasks where speed is less critical, a robotic arm can be a cost-effective choice. It eliminates the need for additional systems such as conveyors, turning mechanisms, stoppers, and gates. As long as the robotic arm meets the required throughput, it presents a more economical solution.

    Economical for Multiple Lines

    A single robotic palletizer can be positioned between several packaging lines and handle multiple product types simultaneously. In contrast, conventional palletizers require separate upstream product accumulation systems to manage multiple lines. By eliminating the need for these additional systems, robotic palletizers reduce overall investment costs.

    Flexible Pattern Formation

    Robotic palletizers offer greater flexibility in changing pattern formations compared to conventional systems. However, it’s important to note that modifying the pattern may impact the palletizer's throughput.

    Chapter 8:What are hybrid palletizers?

    Hybrid palletizers combine the speed and reliability of conventional palletizers with the flexibility of robotic systems. They use traditional row-forming methods, such as turning devices and stoppers, but employ a robotic arm to pick up and place entire layers onto the pallet or stack. This design overcomes the limitation of high-level palletizers, which require products to be moved up by a conveyor, while retaining the advantage of higher throughput.

    Hybrid Palletizer

    Another type of hybrid palletizer features robotic pattern forming. In this setup, a robotic arm handles the orientation and positioning of products in the layer-forming area. Once the layer is complete, a conventional palletizer takes over to place it on the stack and manage additional tasks, such as feeding pallets and slip sheets.

    Conclusion

    • A palletizer is an automated unit load forming machine used to stack and orient several individual products into a single load for a more convenient and economical method of handling, storage, and shipment.
    • Unit load refers to the assembly of materials combined for efficient handling. It is faster and more economical to move a large, single unit instead of several small individual items.
    • There are two main types of palletizers: conventional and robotic. Conventional palletizers use turning devices, stoppers, gates, and stripper aprons to do pattern forming. Pattern forming for robotic palletizers are done by two-link robotic arms or moving beams and telescopic masts.
    • Conventional palletizers are further divided into floor-level and high-level palletizers in which their difference is the infeed entry height, and which remains static (layer or pallet) during operation.
    • Robotic palletizers can be Cartesian, gantry, SCARA, or articulated. These types differ in the type of robot used and the degree of freedom of the robotic arm.
    • Both conventional and robotic palletizers have their advantages. Conventional palletizers are used for faster throughput, while robotic palletizers are used for their simplicity and flexibility. Hybrid palletizers are another type that can utilize both of their advantages.

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      Table of Contents

      What is a Palletizer and How Does It Work?

      History of Palletizers

      Types of Palletizers: Conventional

      Conventional Palletizer Parts

      Types of Palletizers: Robotic

      Robotic Palletizer Parts

      Conventional vs. Robotic Palletizing

      Hybrid Palletizers

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