Palletizing – Conventional or Robot?

First Published: March 18, 2024

Placing packaged items, such as shipping boxes or bags, onto a pallet is an area where automation has been adopted for some time to replace the repetitive manual work.

The last couple of years have seen a major change in how automatic palletizing is handled—the continued march of robots has had an impact.

Conventional Palletizers

Conventional palletizers, or traditional or mechanical palletizers, have been used in packaging lines for decades. They rely on a series of mechanical components, such as chains, conveyors, and guide rails, to transport and arrange packaged products onto pallets.

Conventional Palletizer from Brenton

Operation:

Product Infeed: Packaged products are fed onto the palletizer’s infeed conveyor, typically in a single lane or multiple lanes, depending on the production rate and product dimensions.

Product Arrangement: The products are then guided onto a pattern-forming table or sweep mechanism, which arranges them into the desired pattern for each layer of the pallet load.

Layer Transfer: Once a complete layer is formed, it is transferred onto a pallet stationed below the pattern-forming area, either by a sweeping mechanism or a descending layer deposit system.

Pallet Lowering: After each layer is deposited, the pallet is lowered incrementally to make room for the next layer.

Layer Separation (Optional): In some designs, a layer separating mechanism (e.g., slip sheets, corrugated pads) is inserted between layers to provide stability and facilitate easy removal of individual layers during unloading.

Pallet Discharge: When the desired pallet load height is reached, the completed pallet is discharged from the palletizer, typically onto a conveyor for further handling or stretch wrapping.

Best Suited Applications:

Conventional palletizers are often preferred for applications involving:

– High-speed production lines with consistent product sizes and shapes

– Stable and rigid product packaging (e.g., canned goods, bottled beverages, boxed items)

– Consistent pallet patterns and load configurations

– Lower product diversity, where changeovers are infrequent

Robotic Palletizers

Robotic palletizers, as the name suggests, utilize industrial robots to perform the palletizing process. These systems offer greater flexibility and adaptability compared to conventional palletizers.

Robotic Palletizer from Douglas Machine

Operation:

Product Infeed: Packaged products are typically fed onto the palletizer’s infeed conveyor(s) in a single or multiple lanes, depending on the production rate and product diversity.

Robot Picking: An industrial robot equipped with specialized end-of-arm tooling (EOAT) picks the products from the conveyor and builds the pallet with each item.

The common types of EOAT are:

  • Vacuum: The package is lifted onto the pallet using vacuum suction cups. This is a very common type of tooling and is one of the lowest in cost.
  • Clamp: The tool clamps two sides of the package to lift it. When using this tooling, the package must be strong enough to not be damaged by the force of the clamp.
  • Spatula: This tool inserts fingers beneath the product to lift it. It is often used for fragile products, where the spatula fingers support the weight.
  • Full Layer Sweep: This tool can pick a complete pallet layer in one cycle and can be used on high-speed packaging lines. Because of the weight of many products, a heavy-duty industrial robot is usually specified.

Pallet Pattern Programming: The robot is programmed with various pallet patterns and load configurations, allowing it to place the products onto the pallet in the desired arrangement. A good example of this is the QBox pallet building software from Quest.

Layer Building: The robot builds each layer by precisely placing the products according to the programmed pattern, accounting for factors such as product orientation, weight distribution, and layer stability.

Layer Separation (Optional): Depending on the application, the robot can insert layer separators (e.g., slip sheets, corrugated pads) between layers for added stability and easy unloading.

Pallet Discharge: Once the desired pallet load height is reached, the completed pallet is discharged from the palletizer, typically onto a conveyor, for further handling or stretch wrapping.

Best Suited Applications:

Robotic palletizers are well-suited for applications involving:

– High product diversity and frequent changeovers

– Irregular or unstable product packaging (e.g., bags, pouches, odd shapes)

– Complex pallet patterns and load configurations

– Mixed product pallets (multiple SKUs on a single pallet)

– Harsh or hazardous environments where human intervention should be minimized

It’s worth noting that robotic palletizers often come with a higher initial investment cost compared to conventional palletizers. However, their flexibility, adaptability, and ability to handle a wider range of products and pallet patterns can provide long-term benefits, especially in dynamic production environments with frequent changeovers and product variations.

Conclusion

Both conventional and robotic palletizers have their advantages and limitations, and the choice between them depends on factors such as production requirements, product characteristics, desired level of automation, and overall operational costs. Manufacturers often evaluate their specific needs and constraints to determine the most suitable palletizing solution for their packaging lines.

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