High Level Palletizer

A high level palletizer is a layer-forming machine that receives product at an elevated infeed, builds each layer above the pallet, and lowers the load as it grows. It is the architecture most often chosen for sustained high case rates and for lines where overhead conveyors keep the floor clear. This guide goes deeper into the machine itself: the elevated infeed, how rows and layers form at the top, the apron or stripper plate, the hoist, case turning, and multi-line operation. For the comparison with floor-level designs, see the conventional palletizers guide, and for the other half of the pair, the low level palletizer guide. The palletizing systems overview places both within the wider set of options.

How it works

The layer-forming area stays at one fixed height while the pallet moves. That reverses the logic of a floor-level machine, and most of the design follows from it.

Cases arrive on a conveyor at the top of the machine. One manufacturer guide gives a typical infeed height of about 100 to 144 inches, roughly 2.5 to 3.6 meters. Another supplier gives 84 to 124 inches or higher. The spread reflects different designs, so the exact figure belongs in the quote, not in a generalization.

At the top, cases are metered, turned if the pattern needs it, and gathered into rows. A supplier describing its row-forming layer machine notes that a high-speed switch assigns each case a path, and pneumatic diverters guide cases into the right orientation. Cases that must be turned travel through a turning device before they reach the row-forming area.

A completed row is pushed onto the layer-forming area, and this repeats until the layer is complete. Some designs keep a second row waiting while the previous layer is released, which lets product keep flowing at the infeed and supports faster rates.

The layer sits on a fixed plate, often called an apron or stripper plate. The plate is usually split so it can open along a center line, and the layer waits there until the pallet is in position below it.

A hoist then raises the pallet to just under the apron. The plate opens and withdraws, the layer settles onto the pallet or onto the layer beneath, and the hoist lowers by one layer height. The cycle repeats until the pallet is full, and the finished load descends to a discharge conveyor. Only the pallet moves, and it moves a short distance for each layer, so this action is generally faster than lifting a formed layer upward. That is one reason the architecture is described as the faster conventional design.

Many designs square the layer before release, and some compress it from several sides. One manufacturer describes four-point pneumatic layer squaring before the hoist lowers the load. Compression is often used for bags and compressible packs, and tuning it is part of commissioning for cartons too.

Types and configurations

High level machines differ in how they form the row, how many infeeds they accept, and how they move the pallet. These choices shape both rate and layout.

Row-forming and layer-forming variants

Some machines sweep complete rows onto the layer area with a pusher, while others use a continuous in-line approach that arranges product in motion. A history of the technology from one supplier credits the first mechanical palletizer, in 1948, to the row-forming approach and the in-line type to the 1970s. Ask any supplier how its machine forms rows, how many cases are moved per sweep, and how the next row is staged during layer release.

Infeed arrangements

A single-lane infeed is the simplest. Wider infeeds use a switch to divide cases between lanes so rows and turns form in parallel, which raises capacity. One supplier lists models intended for different speed classes, including a unit described as its fastest row-forming design, but that is a marketing claim. Ask for the rate on your case size and pattern, not the highest rate on the family datasheet.

Multi-line infeed

A high level machine can sometimes accept product from more than one line, which lets a single palletizer replace several manual stations. Each line needs its own conveyor into the machine, and the control logic must decide how to merge streams, which line has priority, and what happens when one stops. The combined case rate must stay within the machine’s layer rate with room for pallet changes. Ask how the machine behaves when one line is starved and how mixed patterns are handled when each line runs a different product. If lines run different SKUs at the same time, a layer machine may be less suitable than a robotic cell.

Pallet and sheet handling

A pallet magazine or dispenser feeds empties to the hoist, and a sheet dispenser places slip sheets or tier sheets when the load needs them. Some machines place a sheet on top of every layer and some only at the base and top. Check the placement method and the effect on cycle time.

Specifications to evaluate

Package compatibility

High level palletizers are used with cases, cartons, trays, shrink bundles, and in some designs bags and cans in packs.

Corrugated cases are the core application. Uniform, rigid cases form rows and layers predictably, and the machine can run at its highest rates. Shrink bundles and trays are common in food, beverage, and tissue, and one supplier lists lightweight shrink bundles and heavy shipping cases among the formats its elevated machines handle.

Bags are possible with layer compression and squaring, but should be tested with the actual bag at the actual rate. Suppliers say lowering the layer is gentler than lifting it, which helps glass and thin cartons. Treat that as a design advantage to verify in a trial, not a guarantee. Irregular or frequently changing shapes are generally easier for robots.

Check the smallest and largest case, the heaviest layer, and the weakest case. Row forming and turning are sensitive to case length and aspect ratio, so very short or very long cases may need special tooling.

Integration upstream and downstream

Upstream, the palletizer needs a controlled stream. When the infeed is overhead, product travels from the packing line to the machine by spiral conveyor or vertical lift. That lift must carry more than the palletizer rate and must not become the bottleneck. The vertical conveyors page explains the types, and the accumulation conveyors page covers the buffer that lets the packer keep running during a pallet change. A comparison from one supplier notes that elevated systems can make better use of vertical space for accumulation, though with more complex mechanisms and maintenance needs.

If the plant already runs overhead conveyors, a high level machine connects at that height without a decline conveyor. That is one of the strongest reasons to select it.

Downstream, the load leaves the discharge conveyor toward a stretch wrapper, a pallet labeler, or an accumulation conveyor. Where a wrapper can be positioned in line, the pallet exit and pallet buffer matter, because a slow wrapper can hold back an otherwise fast machine. Plants that also unload pallets can compare case depalletizers for the reverse operation.

High-rate palletizing in a brewery is described in brewery packaging, and the general application in pallet handling.

Footprint, utilities, controls, and safety

Moving conveyors and the layer-forming stage overhead can free floor space for forklifts, pallet staging, and adjacent equipment, though the machine’s own floor footprint depends on the design, so ask for layout drawings. One guide gives a minimum clear ceiling of about 5 to 7 meters, versus about 4 to 6 meters for low-level designs. Structure for platforms and the lift, floor loading, and sprinkler or lighting clearances belong in the building review.

Expect electrical power and compressed air. Hoists, plate drives, and pneumatic diverters differ between designs, so ask for connected load and air consumption. A PLC and drives coordinate the machine, with an HMI for pattern selection. Ask how patterns are built, stored, and changed, and how the machine communicates with the packer, the lift, and the wrapper.

According to one comparison, the elevated design may require extra safety measures during operation and maintenance. Typical elements include guarding, interlocked doors, light curtains at the infeed and discharge, controlled-entry access, and safe platforms with guardrails for clearing jams. One supplier markets a Category 3 safety package, a classification from the machinery safety control standards. ISO 13849-1 defines performance levels for safety-related control functions, and a hybrid design with a robot adds the ISO 10218 and ANSI/A3 R15.06 family. A site risk assessment of the whole installation, including work at height, should set the safeguarding.

Cost factors

This guide does not state prices; the palletizer cost guide explains how to compare them. Supplier comparisons describe high level machines as generally costing more than floor-level machines, and these drivers are the main reasons:

• Rate class and number of infeeds
• Row-forming method and layer squaring or compression features
• Spiral conveyor or vertical lift to the elevated infeed
• Mezzanine, platforms, or structural work for the elevated section
• Building changes for ceiling height, floor loading, or sprinklers
• Pallet dispenser, sheet dispenser, and discharge conveyors
• Safeguarding for the elevated area and access platforms
• Controls platform, patterns, and integration with line equipment
• Installation, commissioning, training, and spare parts

Compare complete scopes. A machine quote without the lift, platforms, and building work can look far cheaper than it is.

Selection checklist

• Measure ceiling height, structural clearances, and floor loading.
• Record whether overhead conveyors already exist and at what height.
• Define the sustained case rate for each line, the case sizes, and the patterns.
• Decide the number of infeeds, now and over the machine’s life.
• Define the lift or spiral capacity and who supplies it.
• Specify pallet, slip sheet, and tier sheet handling.
• Decide the wrapper and pallet buffer arrangement.
• Ask about squaring, compression, and fragile product handling.
• Request the safeguarding approach, including work at height.
• Confirm maintenance access and training requirements.
• Ask for the changeover method and the time on the hardest change.
• Request an acceptance test with production cases.

Common mistakes

• Choosing for the headline rate alone. Check the sustained rate on the actual pattern.
• Forgetting the lift. The elevated infeed needs conveyors that carry more than the machine rate.
• Skipping the building review. Ceiling, floor loading, and lighting can force costly changes.
• Underestimating maintenance at height. Jams and adjustments happen on platforms, so safe access matters. For older machines, see the guide on palletizer retrofit and upgrades.
• Ignoring changeover, when frequent format changes can cancel the speed advantage.
• Leaving multi-line logic vague. One line can starve another unless accumulation and priority rules are defined.
• Specifying the wrapper late, when a slow wrapper limits pallet output.
• Comparing partial scopes. Include conveyors, platforms, and building work in every quote.

Alternatives

A low level palletizer takes product at floor height and lifts each layer, which suits moderate rates, lower ceilings, and simple layouts, and it avoids the lift. A robotic palletizer suits many SKUs, mixed packages, and frequent pattern changes, and the robotic vs conventional palletizer guide compares them. For the wider decision, the guide to choosing a palletizer lists the factors, and the case palletizers page covers case handling that applies to every architecture. If the plant has one fast line, tall ceilings, and overhead conveyors, a high level machine is usually the first design to price.