Case Depalletizer

A case depalletizer unloads packed cartons, shipping cases, and trays from pallets and puts them on a conveyor in a controlled flow. It differs from a bulk machine in one basic way: the unit it moves is a package that holds product, not a loose container. That changes the grip, the way layers are separated, the way damaged cases are found, and the way the next machine receives the load. For the family of machines as a whole, see the depalletizing systems hub. For loose empty containers, see the bulk depalletizer guide and the bottle depalletizer guide.

How it works

A case depalletizer has to find the load, separate cases, move them, and clear the empty pallet. The steps below describe a typical cell, and details vary by machine.

1. A fork truck or pallet conveyor delivers the pallet. Stretch film, bands, and corner boards are removed first, either by hand or by a film cutter or destrapper upstream.
2. A sensor, light curtain, or vision system finds the top layer and, in robotic cells, the position of each case. A fixed machine relies on the pallet pattern being the one it expects.
3. A gripper removes cases from the top layer. Depending on the design, it takes one case, a row, or a complete layer, and a conventional machine may push or lift a whole layer instead.
4. The cases are set on an outfeed conveyor. A robot may place each case in a set position and orientation, while a layer machine places the layer on a table that then feeds a conveyor.
5. A slip sheet or tier sheet between layers is lifted away and stacked. Supplier literature notes tools that handle slip sheets and top sheets.
6. Some cells check that only one case was placed, to avoid putting two on the conveyor at once. One supplier describes imaging the place zone for this purpose.
7. When the last layer is gone, the empty pallet leaves the cell for stacking or pickup, and the next full pallet enters.

A well-designed cell takes the top layer completely before starting the next one. One supplier describes this as a way to reduce the risk of toppling.

Types and configurations

What is being unloaded

Full cases are sealed cartons or shrink-wrapped trays of filled product. They supply a distribution center flow, feed a case unpacker at the start of a repack line, or move finished goods to a sorter. Case strength, weight, and surface matter, because the gripper must hold the case without crushing it.

Empty shippers and carton blanks arrive on pallets and feed a case erector, a packer, or a sleeve loader. They are light, may be open or collapsed, and often shift in their pallet pattern, so gripping them without deforming them takes careful tooling.

Trays, with or without film, are common in food, beverage, and produce packaging. Supplier literature lists wrapped and unwrapped trays and cartons in trays among products that robotic cells handle. Open trays have fewer flat surfaces to grip, so they may need fork-style or clamping tools.

Some suppliers offer a single cell for cases, trays, pails, and jugs. Treat bags, pails, and jugs as separate applications until the supplier confirms the grip method and rate.

Row, layer, and single-case unloading

The unit taken from the pallet changes the rate and the risks.

Supplier literature describes cells that handle products individually, by row, or by full layer depending on production goals and product mix. The choice depends on throughput needed, case rigidity, and whether the pattern can be recognized and handled in groups. Rows and layers may also be rotated or split after pickup, so a layer cell can still feed a single-file conveyor.

Conventional versus robotic case depalletizing

Conventional case depalletizers are fixed-motion machines, usually layer or row based. They work best when pallets always hold the same product in the same pattern, and for plants that need a steady, high rate. Because the motion is dedicated, changing to another pattern usually means adjusting guides, recipes, or tooling. They are generally simpler to program and maintain, and cheaper to run for a single product.

A robotic case depalletizer carries a gripper on an arm and may use vision to see the load. Supplier literature describes vacuum, clamp, fork-style, magnetic, and layer-gripping tools, and tool changers for plants that run several case types. Robots handle variable patterns and can run many SKUs without hardware changes. They tend to have a lower rate per cell than a dedicated layer machine, and they depend on vision and software, which need setup and care.

The comparison is a general starting point drawn from how suppliers describe the two approaches. Rates and capability depend on the case, the pallet, and the cell design, so ask for tests on your own loads. The robotic palletizer guide discusses the same robot cell issues in reverse, since many robotic cells can both palletize and depalletize.

Hybrid and manual-assist arrangements

Some plants add a lift table, pallet positioner, or vacuum assist so an operator can unload cases at a good height. These suit low volume and do not remove the ergonomic load of repeated lifting. A hybrid cell may use a layer machine for standard pallets and a manual station for odd loads.

Mixed-SKU and incoming-goods applications

The hardest case depalletizing is not a fast uniform pallet. It is an unpredictable one.

Single-SKU pallets hold identical cases in a known pattern, and a conventional layer machine or a simple robot with a pattern library handles them. Rainbow pallets have a different single product on each layer. One supplier describes rainbow depalletizing as handling rows of homogeneous layers where each layer can differ in shape, size, and weight, so the machine has to detect the change between layers.

Mixed-case pallets combine products and sizes within a layer with no pattern. Mixed-case palletizing is more common as plants and distributors ship many different SKUs in smaller quantities, and unloading these pallets needs vision to find each case and decide where to grip. Pallets from outside suppliers vary in pattern, wrap, case condition, and label position, which is why supplier literature says vision systems are deployed mainly in warehouses and distribution centers.

Supplier descriptions of mixed-case cells share some features:

• The system analyzes the pallet and sends picking commands for each pickable case. It may find skewed layers and compare the case count with what it expects.
• Flat black cases, cases with alternating colors on the flaps, banded cases, and cases with reflective tape or gaps can be hard to see. One supplier lists these among conditions its software is built for. Another describes a light array that shields the camera from overhead light.
• If a case is not recognized, some systems start a remote call for a person to help, while others eject the case for manual reintroduction.
• One supplier case study reports a mixed-case cell with a daily volume of 6,500 cases and capacity for up to 10,000 cases a day. That is one plant’s example, not a rate to expect elsewhere. Ask for a rate on your pallets, including recognition time, unrecognized cases, and pallet changes.
• In that case study, cases move to an orientation inspection station that scans the labels. Cases found in the correct orientation continue downstream, and any case that cannot be identified is ejected.

Specifications to evaluate

Request every value in writing for your own cases, pallets, and line.

Quote comparisons only make sense on the same basis. A robot rated by cycles per minute moves different numbers of cases per hour depending on whether each cycle picks one case, a row, or a layer.

Container and package compatibility

Corrugated shipping cases are the most common load. Check board strength, case condition, and whether the top surface is flat enough for a vacuum gripper, since printed or glossy coatings change vacuum performance. Shrink-wrapped trays and film-wrapped packs may have loose or wrinkled film that affects vacuum sealing. Clamp or fork-style tools can help, and the supplier should confirm the wrap type.

Empty cases and blanks are light and sometimes open or collapsed. Layer squaring and a gentle grip help. Confirm the pattern can be recognized and that cases do not nest or stick.

For heavy cases, the payload limits of the robot, gripper, and conveyor become important. Confirm the heaviest case and whether the gripper can lift it with a margin. Incoming pallets also often hold damaged or crushed cases, so decide in advance whether the cell should pick them, reject them, or stop.

Bags, bales, pails, and drums need their own tooling. Some suppliers list these among products their robots can handle, but each deserves a separate check.

Integration upstream and downstream

Pallets arrive by fork truck, pallet jack, or conveyor. Plan film removal, banding removal, staging space, and a way to present the pallet in a repeatable position. For robotic cells, light protection for the vision system and clear pallet visibility matter. Incoming pallets should meet an agreed specification, such as pattern, overhang, and wrap type, so the cell sees consistent loads.

Next in the line may be a case unpacker, an uncaser, a case opener, or a packing machine. These often need the case in one orientation and at a set spacing, and a case that arrives sideways, upside down, or with the wrong face forward may jam the unpacker or keep it from opening the case. There are several ways to meet this need:

• A robot can rotate each case before setting it down. A layer machine often has fixed orientation, so the pallet pattern must match.
• A guided turn, rotating section, or pop-up diverter can turn cases after they leave the depalletizer. Supplier literature mentions roller or belt conveyors that unscramble, singulate, orient, and position products after depalletizing. See case conveyors for the usual hardware.
• A scan station can read labels and verify that cases are right side up, with unreadable cases ejected for manual handling.
• Unpackers have a cycle time, so the feed needs consistent gaps. An accumulation area lets the depalletizer and unpacker run at different rates, and accumulation conveyors hold the buffer.

Agree on orientation, face, flap direction, spacing, and rate with the supplier of the next machine, and write the agreement into both specifications.

Define start, stop, fault, full, and starved signals between the depalletizer, conveyors, and the next machine. When the downstream machine stops, the depalletizer should stop placing cases in a controlled order and resume without lost or doubled cases.

Incoming-goods use in food plants is covered in food packaging, with the general application in case handling.

Footprint, utilities, controls, and safety

A conventional machine needs space for the elevator, layer table, pallet infeed, empty pallet exit, and sheet stacker. A robotic cell needs room for robot reach, fencing, pallet stations, and often two pallet positions so one pallet can be changed while another is worked. Request a layout drawing showing fork truck access, door openings, and maintenance clearance.

Electric power is standard, and compressed air or vacuum is typical for grippers and sheet handling. Values depend on the machine and gripper, so ask for them on the data sheet. For controls, look for a programmable controller, a clear operator screen, recipes for pallet patterns, and diagnostics. Vision-based cells add camera views, image logs, and setup tools.

Main hazards include falling cases, robot and elevator motion, pinch and crush points, moving pallets, fork truck interaction near pallet stations, and stored energy in pneumatic or gravity-loaded parts. Typical controls include perimeter fencing, interlocked gates, light curtains, safety-rated scanners, emergency stops, and controlled pallet exchange zones.

In the United States, 29 CFR 1910.212 requires one or more methods of machine guarding to protect operators and others in the machine area from hazards such as nip points and rotating parts. The lockout/tagout rule, 29 CFR 1910.147, applies to servicing and maintenance in which unexpected startup or release of stored energy could injure workers, and it requires an energy control program. A suspended gripper or raised elevator can carry stored energy after power is removed. Supplier guarding does not replace a site-specific risk assessment, which should cover the entire installation, including pallet exchange, downstream conveyors, and maintenance access.

Cost factors

This page does not give prices. The main drivers of a quote are:

• A robot cell adds the arm, gripper, vision, and guarding, while a layer machine adds a frame, elevator, and drives.
• Higher rates and layer handling need more capable drives and grippers.
• More patterns, case types, and mixed pallets need more software, tooling, and testing. Vacuum, clamp, fork, and layer tools differ in cost, and plants with many case types may need a tool changer.
• Sheet removal, empty pallet stacking, and film or strap removal each add equipment.
• Turning, scanning, spacing, and accumulation can be a large share of the project. The packaging conveyor cost guide lists drivers for the conveyor side.
• Guarding, scanners, and documentation depend on the site, and installation covers rigging, utilities, programming, commissioning, and training for operators and maintenance staff.

Compare installed cost together with labor, ergonomics, damaged-case losses, and downtime, not only the machine price.

Selection checklist

1. Define the load: full cases, empty cases, or trays, with dimensions, weights, and construction.
2. List pallet patterns, load heights, and variation, including mixed and rainbow pallets.
3. Describe the incoming condition: film, bands, sheets, damaged cases, and label positions.
4. Set the required rate in cases per minute, based on the next machine plus a margin.
5. Decide the pick unit: single, row, or layer.
6. Specify the orientation, face, and spacing needed at discharge.
7. Count products and how often they change.
8. Plan pallet infeed, staging, and empty pallet handling.
9. Confirm floor space, utilities, and fork truck routes.
10. Set the safety scope, guarding, and the site risk assessment.
11. Agree acceptance tests on your own pallets, including the worst incoming loads.

The commissioning and acceptance checklist covers scope, documentation, and acceptance testing from the buyer’s side.

Common mistakes

• Planning on the demonstration pallet. Real incoming pallets are messier than a test load.
• Mixing up rate bases. Cycles per minute, cases per minute, and layers per minute are different measures.
• Ignoring orientation. A fast depalletizer that delivers cases at random only moves the problem to the unpacker.
• Underestimating case variety. Surface finish, wrap, and construction change grip performance.
• Having no plan for exceptions. Decide what happens when a case is crushed, unreadable, or missing.
• Skipping the buffer. Without accumulation, each pallet change stops the downstream machine.
• Choosing a robot for a uniform pallet. A dedicated layer machine may give a higher rate for a single product.
• Adding guarding late. Pallet exchange and jam clearing need safe access from the start.

Alternatives

If the load is loose empty containers rather than packed cases, use a bulk depalletizer or a bottle depalletizer. Where all pallets follow one pattern, a layer machine without a robot gives high rate and simple operation. A lift table or vacuum hoist reduces strain at low volume, though it does not remove the need for labor.

Some plants avoid depalletizing by delivering cases to the line on conveyors from the supplier or an upstream packer. That changes the supply chain, not the equipment.

If the same plant builds pallets, the pattern and case choices at the palletizing end affect how easily they can be unloaded later. See case palletizers and the guide on how to choose a palletizer.

Browse the equipment map to see how depalletizing connects to conveyors and palletizing.