Depalletizer Product

Overview

A depalletizer automatically removes stacked layers of cartons or trays from an incoming pallet and feeds them onto a conveyor line downstream. The machine is positioned at the head of a packaging line, accepting full pallets of finished goods and singulating them for secondary operations (case labelling, case erecting for new product, or direct shipping). Depalletizers are found in beverage bottling, fresh-food distribution, consumer goods and logistics centres. Speed ranges from 60 to 180 layers per hour, depending on load weight, layer height and whether slip sheets must be separated.

Pallet handling and lift

The incoming pallet is positioned on the Pallet Table. Fine positioning jacks (the Position Jack array) shift the pallet slightly so its corner aligns with the pickup head, or optional rotation via a Rotate Motor may centre the layers. A Pallet Lift (powered by a Lift Pump) raises the pallet stack so the topmost layer sits at the height of the Layer Pickup Head. The lift travels via vertical Lift Guide rails, powered by hydraulic or pneumatic Lift Cylinder units. As each layer is removed, the pallet is lowered slightly so the next layer rises to pickup height.

Layer pickup head

The Layer Pickup Head is the critical assembly. It contains 8–16 large rubber Suction Cup elements (each 50–100 mm diameter) arranged over the footprint of the layer. A Vacuum Block (an aluminium manifold with drilled ports) connects all cups to a central evacuation point. A Blower Motor generates vacuum (600–800 mbar) by pulling air through the manifold. When the head descends onto the top layer, all cups make contact, and the vacuum is applied. Atmospheric pressure then holds the entire layer (~100–500 kg) suspended as a rigid mass. Once gripped, a pneumatic or servo actuator lifts the head vertically, extracting the layer cleanly from the stack.

Slip sheet separation

Most palletised layers are separated by a slip sheet (a thin corrugated board or plastic sheet) to allow manual forking if needed. The Slip Sheet Removal system engages as the layer is lifted. Mechanical fingers (part of the Sheet Extractor) grip the leading edge of the slip sheet below the layer. A Extractor Actuator (pneumatic or servo) then pulls the sheet horizontally out from under the lifted layer, separating it from the cartons above. The sheet is then either discarded or dropped into a recycling chute. Modern slip sheet materials are biodegradable cardboard or lightweight plastic.

Conveyor discharge

Once the slip sheet is removed, the pickup head advances horizontally over the Infeed Conveyor. The vacuum is released, and the layer gently sets down on the moving belt. The Conveyor Motor (variable-speed AC) drives the Conveyor Belt, which can be a heavy-duty modular plastic belt or a slat conveyor. The belt carries the singulated layer downstream to the next station: a case labeller, case erector, or palletiser.

Coordination and control

All operations are orchestrated by the Control PLC, which sequences the lift, pickup head descent, vacuum-on, lift-up, horizontal advance, slip-sheet extraction, and belt discharge. The Main Drive — a variable-frequency motor synchronized to the PLC — coordinates mechanical actions if the machine uses cam timing or shaft-driven actuators. Modern machines rely more on individual servo motors and pneumatic solenoids driven by the PLC. The HMI Panel displays pallet count, current layer, any jams or misdetections, and throughput in layers per minute.

Precision and misdetection

Depalletizers must handle real-world variability: slightly tilted pallets, sagging cardboard, oversized cases, or mixed pallet heights on the same job. The machine uses proximity sensors or load cells to detect when a layer is successfully gripped (a sudden shift in vacuum draw or pressure spike during the lift). If detection fails, the PLC triggers an alarm and halts the layer from being conveyed, alerting the operator. Pallet position can be automatically corrected in real-time by the fine-positioning jacks.

Safety and guarding

The Safety Guarding system includes interlocked guards (the Guard Gate) around the pallet station and pickup head, Interlock Switch elements that disable machine motion if a guard is opened, and Light Curtain presence-sensing safety devices monitoring the discharge conveyor. An emergency stop button is always accessible to the operator. The Safety Relay implements the safety circuit, meeting PLd or PLe standards depending on local risk assessment.

Alternative pickup technologies

Some depalletizers use mechanical vacuum finger arrays instead of continuous suction cups, allowing them to work with higher layers (~800 kg) or more textured carton surfaces. Other machines employ robotic arms with specialized clamps for extremely high-speed, very light layers. Slip-sheet removal can be fully vacuum-based (pneumatic fingers) or mechanical (motorised rollers or blade), depending on sheet material and stiffness. The choice depends on throughput requirements and carton stability.