Robotic Palletizer

A robotic palletizer utilizes a robotic arm to handle, position, and stack individual items into a cohesive load. Representing the evolution of palletizing technology, these systems are poised to surpass traditional palletizers.

Robotic Palletizer
A robotic palletizer utilizes a robotic arm to handle, position, and stack individual items into a cohesive load. Representing the evolution of palletizing technology, these systems are poised to surpass traditional palletizers. Their benefits, including reduced upfront costs, adaptability, and capability to perform multiple tasks, position them as the preferred option in specific scenarios. Nevertheless, challenges related to speed, product size variability, and durability prevent them from fully supplanting conventional palletizers.

Like conventional palletizers, robotic palletizers leverage the concept of unit load. Unit load involves consolidating materials to facilitate efficient handling. Transporting a single large unit is quicker and more cost-effective than moving numerous smaller items individually. Finished goods are typically packaged in containers such as boxes, cases, trays, or crates, which are then aggregated onto pallets or roll cages to form a unified unit. These containers constitute secondary unit loads, while pallets or roll cages supporting them form tertiary unit loads.

Before the advent of automated palletizing, manual hand stacking was the norm for organizing products into pallet loads for storage and distribution. However, this method proved slow due to the labour-intensive nature relative to its output. Pallets and pallet handling emerged as crucial logistics tools in the early 20th century, especially during World War II, as the transportation of heavier loads became more rapid, necessitating new material handling and storage capabilities. The first mechanical palletizer, developed by Larson Corp. in 1948, utilized a row-forming technique. Materials were arranged on a row-forming area before being transferred to another section where layers were stacked. This process continued until a complete stack of materials was formed and ready for pallet placement, laying the groundwork for conventional palletizers.

In the 1980s, robotic palletizers entered the scene. These systems employed a robotic arm equipped with an end effector or product gripper to pick up items from conveyors or layer tables and position them on pallets. The end-of-arm tool could be a mechanical, suction, or magnetic gripper, offering versatility in handling various types of products.

Advantages of Robotic Palletizers



Automatic palletizers typically provide numerous advantages within a packaging or production line. They enhance manufacturing efficiency by removing the human element that can impede the plant's operational speed. The benefits derived from palletizers often outweigh the initial investment costs. Some of the advantages of utilizing palletizers include:

Enhanced productivity: 

Palletizers streamline the unitization process by eliminating manual labor. They operate with greater efficiency, lifting heavier loads and completing tasks more rapidly. Unlike humans, they do not tire or risk injury. With regular maintenance, palletizers can run consistently, 24/7, minimizing potential bottlenecks in the packaging line.

Improved product handling: 

Automated palletizers execute pre-programmed movements, ensuring careful product handling without damage. Unlike human operators, they don't require continual decision-making, reducing the risk of errors and ensuring better product handling overall.

Enhanced workplace safety: 

Well-designed palletizers mitigate workplace risks linked to manual labor. Manual palletizing exposes workers to hazards such as falls, slips, trips, and crushing incidents. Additionally, repetitive tasks like reaching and stacking can cause muscle strains and lead to lower back injuries, posing long-term health risks to employees.

Decreased operating expenses: 

In many scenarios, especially within sizable packaging systems, investing in a palletizer yields favourable cost-benefit outcomes. Operational cost savings stem from heightened throughput, minimized product waste, and decreased labor expenses.

If the attributes are insufficient, robotic palletizers offer additional distinctive advantages. When considering the purchase of a palletizer, the initial inquiry often revolves around the choice between robotic and conventional models. Therefore, understanding the strengths and weaknesses of each type is crucial. Both varieties possess unique merits tailored to specific applications. The following table provides a comparison between the two types of equipment.

Types of Robotic Palletizers



Classification of robotic palletizers is based on their configuration and construction, with different configurations determined by the mode of operation. Robotic palletizers can operate independently or in conjunction with other units, and they may also fulfill functions beyond palletizing. Listed below are various types of robotic palletizers categorized by configuration.

Single, In-Line Palletizer

This configuration, the simplest and most prevalent type, comprises a single robotic palletizer. It handles palletizing tasks, with certain designs offering additional capabilities like slip sheet and pallet dispensing, as well as stretch wrapping.

Single, In-Line palletizers can accommodate one or multiple palletizing lines, each potentially featuring identical or distinct product SKUs, depending on the palletizer's design. Typically equipped with articulated arms and customized end-of-arm-tools, these palletizers offer high versatility.

However, their drawback lies in their lower throughput capacity.

Palletizing-Depalletizing: 

This type of palletizer introduces an additional layer of versatility through depalletizing functionality. Depalletizing involves the reverse process of disassembling individual items from unitized or palletized loads. This feature proves valuable in applications requiring the unloading of products from mixed pallets. Additionally, the depalletizing robot is capable of sporting goods based on product SKUs.

Typically, robotic palletizers specialize in either palletizing or depalletizing functions, seldom performing both simultaneously. However, when a machine is labelled as a palletizer-depalletize, it signifies programmable capabilities for both functions. Palletizers are primarily utilized in end-of-line processes encompassing packaging and storage, while depalletizes are employed in the unloading and distribution of raw materials such as empty bottles, boxes, and cases. The benefits provided by palletizers extend to depalletizes as well.

Layer-Forming Palletizer

This robotic palletizer configuration involves multiple robots working collaboratively. Layer forming entails an integrated system wherein each robot performs a specific task. A basic layer forming system typically consists of two robots: one assembling the layers and the other stacking them. This process significantly enhances the throughput of the entire palletizing system.

The number and types of robots, programmed actions, and other features vary from manufacturer to manufacturer. Other designs also combine conventional and robotic palletizers. These palletizers are known as hybrid palletizers. In this configuration, layer forming is done by a conventional palletizer. Conventional palletizers are better suited for layer forming since they can easily and quickly accept incoming products from conveyor belts. After layer forming, robotic palletizers pick up the entire layer and stack them from the previous. They are much more efficient in stacking since they are designed in pick and place movements. 

Mixed Configuration Palletizer

Mixed palletizing refers to the ability of robotic palletizers to accept different products and unitize them into a single pallet. Mixed configuration robotic palletizers are usually top-of-the-line. They usually have sophisticated programs, custom end-of-arm-tools, and sensors. They are the most versatile palletizers since they can perform minute adjustments to their arm and tooling motions without the need for reprogramming. They can adapt to the profile of the product and determine its location on the stack. Mixed configuration is useful in high SKU packaging, storage, and distribution lines.

Robotic palletizers can also be categorized based on their construction, with each type distinguished by its range of allowable movement. The complexity of their construction correlates with the extent of their movement capabilities. Here are the four primary types of robotic palletizers based on their construction:

Cartesian Palletizer

This type of palletizer features an end-of-arm tool capable of movement in three directions of space, known as the Cartesian axes. Its structure typically comprises beams and a telescopic mast actuated by servo motors, geared rollers, rack and pinion, chain and sprocket, or lead screw mechanisms. Cartesian palletizers are characterized by slower speeds and are best suited for handling products with consistent weights and sizes. Their end-of-arm tooling tends to be relatively basic, making them suitable primarily for pick-and-place applications. Generally, Cartesian palletizers are the most cost-effective option, suitable for single line speeds of up to 10 items per minute.

Gantry Palletizer

A gantry palletizer comprises an end-of-arm tool or end effector assembly mounted on a beam capable of movement along one axis. The beam also moves along another axis, facilitating horizontal movement. For vertical motion, the end effector assembly may utilize a telescopic or articulated arm capable of folding or extending vertically. Gantry palletizers are categorized as Cartesian palletizers since they demonstrate linear movement along the three Cartesian axes. While primarily performing pick-and-place operations, they typically operate at slower speeds compared to Cartesian robots. Additionally, gantry palletizers tend to be larger and therefore more expensive. However, they offer the advantage of lifting heavier loads.

Selective Compliant Articulated Robot Arm Palletizer (SCARA Palletizer)

A SCARA-type palletizer features an arm that is compliant or flexible in the horizontal plane but remains rigid in the vertical direction, hence the term "Selective Compliant." Its articulated robot arm resembles a human arm, consisting of two links connected by a joint at their ends. Typically, this joint offers a single degree of freedom, allowing the robotic arm to extend or fold. SCARA palletizers are typically faster than Cartesian palletizers and can cater to multiple palletizing lines, achieving speeds of approximately 20 items per minute.

Articulated Palletizer

Articulated palletizers offer two additional degrees of freedom to the end effector compared to SCARA palletizers. They represent the most advanced type, closely resembling a human arm in functionality. The end-of-arm tool is attached to a wrist with one or two degrees of freedom. Articulated palletizers feature arms connected by a simple joint at one end, like SCARA models. However, they lack a mast. Instead, one arm is affixed to a swivel joint with a fixed base, enabling more flexible movement. This type operates faster than SCARA palletizers and can manage multiple production lines, achieving speeds of approximately 25 items per minute.
Robotic Palletizer


Common Robotic Palletizer Parts



End-of-arm-tools, columns, arms, and joints are terms frequently utilized in previous discussions to delineate the various components of robotic palletizers. In contrast to conventional palletizers, the components of robotic palletizers bear a closer resemblance to those found in automated assembly and manufacturing systems. Mechanically speaking, a robotic palletizer can be viewed as an assembly of links and joints, each designated according to its function within the robotic system and its placement within the assembly.

Column or Mast

Columns and masts represent the vertical components directly affixed to a fixed base (in Cartesian, gantry, and SCARA types) or a rotating base (in articulated models). Responsible for bearing the weight of the load and the entire palletizer assembly, columns serve as attachment points for the beam, arm, and end effector assemblies. Various mechanisms such as hydraulics, servo motors, lead screws, or chain drives facilitate the vertical movement of connected parts, enabling them to ascend or descend.

Beams

Beams constitute horizontal load-bearing elements that support the end effector assembly or end-of-arm-tool. Equipped with guided rails, beams facilitate the translational movement of a trolley carrying the tool. While a single beam confines movement to a single axis, a two-beam assembly allows for movement within the horizontal plane. Beams are commonly found in simpler robotic palletizers like Cartesian and gantry types, except for gantry palletizers utilizing a robotic arm as an end effector.

Arms

Arms are comprised of two-link mechanisms that facilitate movement of the end-of-arm-tool in two- or three-dimensional space through rotation, extension, or folding. Connected by joints offering one or two degrees of freedom, the range of motion of the palletizer is determined by the length of the arms and the permitted motion of the joints. Arms are specific to SCARA and articulated palletizer types.

Joints

Joints enable rotational or translational movement between the links of an arm. The number of joints present in a palletizer system varies based on the desired versatility. A robotic palletizer arm with full, unrestricted motion typically comprises six joints, with each joint providing a single degree of freedom.

Wrist:

The wrist serves as the joint in a robotic arm responsible for carrying the end-of-arm-tool. Typically, it facilitates rotational movement to adjust the orientation of the tool. Some designs offer additional functionality, allowing for two-degree movement types.

End-of-Arm-Tools (EOAT)



End-of-arm-tools, also known as end effectors, represent a critical component of a robotic palletizer, embodying the machine's versatility. These devices are tasked with picking up and placing the product in its designated location and orientation within the stack. EOATs can be engineered to handle not only finished products but also various other materials such as packaging materials, wrappers, slip sheets, pallets, and more.

Varieties of End-of-Arm-Tools

The end-of-arm-tool, or EOAT, stands as the component distinguishing robotic palletizers from their conventional counterparts. As discussed in the preceding section, this element is fundamental to the versatility of robotic palletizers. Presented below are several of the most utilized EOATs within the palletizing industry.

Clamps

These EOATs function by lifting the product through clamping and gripping its sides. Typically, one part of the clamp remains stationary while the other moves. Grip is achieved by bringing the movable part closer to the stationary part and against the product. Clamps have the capability to gather and position multiple products with consistent orientation simultaneously, facilitating accelerated throughput.

Forks:

These end effectors are designed for products requiring support from underneath. Offering additional stability, forks can handle heavier loads without risking damage to the product's sides. Their operational principle is akin to clamp types, involving the use of one side to push the products onto the fork. As products are pushed, they are loaded onto the fork for transport. Like clamps, forks have the capability to gather and position multiple products simultaneously.

Fingers

Finger end effectors are mechanical tools capable of opening and closing in two directions. They not only grip the product at its sides but also offer support from underneath, rendering them more sophisticated than clamp and fork types. Fingers are frequently employed for handling delicate products or items packed in fragile materials such as paper or thin plastic sheets.

Vacuum or Suction Cups

These end effectors utilize pneumatic systems equipped with a venture device to generate vacuum pressure. Vacuum types employ multiple suction cups to secure the product on its upper surface. Unlike mechanical types, they don't inflict damage on the packaging material during product retrieval. Moreover, they boast greater reliability due to their fewer moving parts. However, vacuum types do have limitations regarding weight capacity. Additionally, they palletize at slower speeds because they begin to lose grip when rapidly accelerating the product.

Magnetic Grippers

This EOAT variant employs magnetic devices to lift either magnetic products or items enclosed in magnetic casings or packaging. Permanent magnets are viable options as they don't require continuous power consumption; however, they necessitate a mechanical device for detaching the collected object. Electromagnets, on the other hand, offer straightforward operation, enabling the object to be lifted or released simply by supplying or cutting power to the electromagnet. While magnetic grippers have their advantages, their suitability as a palletizer EOAT is restricted since only a select few products exhibit magnetic properties. Moreover, their applicability is further limited by the potential for magnetism to cause damage or induce magnetic properties in non-magnetic items.

Custom

Custom EOATs are specially crafted tools designed for the handling of irregularly shaped products. These tools can incorporate a blend of mechanical, pneumatic, or magnetic actuators, enhancing the versatility of the palletizer. Additionally, custom EOATs enable the robotic palletizer to undertake secondary tasks such as dispensing and wrapping, further augmenting its functionality.

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