Palletizing conveyors
The conveyors around a palletizer: case infeed, accumulation, gapping, turners, pallet conveyors, pallet and slip sheet dispensers, inspection, and safety.
A palletizer is only as fast as the conveyors around it. Cases must arrive spaced, turned, and on time. Empty pallets and sheets must be ready for each load. Full pallets must leave before the next one is done. This page covers each piece of the palletizer system with models and ratings from their makers.
All speeds and capacities here are makers’ ratings. Real output depends on your cases, pattern, and how the whole line is controlled.
The parts of a palletizing line
Columbia, a palletizer maker, says it supplies “complete palletizing lines including case conveyor, spirals, palletizers, pallet conveyor, stretch wrappers, barcode scanners and more” (Columbia). Its HL6200 cut sheet shows a common layout in four parts: infeed, palletizer, pallet dispenser, and discharge (Columbia HL6200).
A typical line runs in this order:
- Case infeed and accumulation.
- Metering, gapping, and turning.
- Merging, if more than one line feeds the palletizer.
- The palletizer, fed by a pallet dispenser and sometimes a sheet dispenser.
- Full-pallet conveyor to a stretch wrapper and a pickup point.
Case infeed and accumulation
Accumulation lets cases queue up when the palletizer pauses. A pause can be a pallet change or a sheet placement. Without a queue, the line upstream has to stop.
Zero-pressure accumulation holds cases in zones so they do not push on each other. Hytrol’s 190-E24EZ is one example. Each zone has its own 24-volt motor and an EZLogic controller. Zones come in 18, 24, 30, or 36 in. lengths. Hytrol rates it at 37 lb per foot and 75 lb per zone, at a standard speed of 25 to 174 ft per minute (Hytrol E24 sheet).
Hytrol says that if an EZLogic controller “does not detect the presence of product for a selectable time period, the controller stops the zone from driving.”
Metering, gapping, and case turners
A palletizer often needs a set gap between cases. A gapper creates it by running each belt faster than the one before. Hytrol says “Having an adequate gap gives packages room to turn during merging and combining” (Hytrol). It describes two methods:
- Blow through. The belts run at fixed speeds. Hytrol says this suits “products with similar sizes.”
- Gap optimization. Sensors watch each case and adjust speed. Hytrol says it “works best with packages of various sizes.”
A case turner spins cases to the angle the pattern needs. The Finger Lakes Conveyors FLC-3100 uses two belts at different speeds. The speed difference turns the case. Finger Lakes says it can give “90 degree rotation of cases or trays.” It also has an “in-feed metering belt section to assist in proper product spacing while rotating” (Finger Lakes Conveyors). Many conventional palletizers have turning devices built in. Columbia lists “Turning Devices” in its accessories.
Merging more than one line
One palletizer can serve two or more packing lines. Columbia lists a “Dual infeed configuration” as an option on its HL6200. A robot cell can also pick from more than one infeed. See dual-line robot cells.
Merging needs gaps and controls. The merge has to know which line sends the next case. With mixed SKUs (stock keeping units, or distinct products), it must also track which product is which. Columbia lists barcode scanners as part of the lines it supplies. For multi-SKU loads, see mixed case palletizing.
Full-pallet conveyors
Pallet conveyors move heavy loads at low speed. The three main parts are straight conveyors, transfers, and turntables.
Chain-driven live roller (CDLR). Roller chains drive each roller. Omni Metalcraft rates its CDLR by roller size (Omni Metalcraft):
| Roller diameter | Omni’s rated capacity per unit load |
|---|---|
| 1.9 in. | Up to 1,500 lb |
| 2.5 in. | Up to 3,500 lb |
| 2 9/16 in. | Up to 4,000 lb |
| 3.5 in. | Up to 10,000 lb |
| 4 in. | Up to 15,000 lb |
| 5 in. | Up to 25,000 lb |
| 6 in. | Up to 30,000 lb |
Omni’s spec sheet lists speeds “Up to 150 FPM for straights and 80 FPM for curves” (Omni CDLR spec). FPM means feet per minute.
Zero-pressure pallet accumulation. Hytrol’s 25-CRE24EZ is a chain-driven roller conveyor with EZLogic zones. Hytrol rates it at a standard 28 ft per minute, with a maximum unit load of 1,300 lb (Hytrol E24 sheet). Many full pallets weigh more than that, such as beverages, bags, and building materials. Size pallet conveyor to your heaviest load plus the pallet. Heavier loads need heavier CDLR, such as the larger rollers in the Omni table above.
Chain transfer. A chain transfer moves a pallet 90 degrees onto a side conveyor. Chains rise between the rollers, lift the pallet, and carry it sideways. Omni lists palletizing and stretch wrapping as common uses. Its chart runs from 500 lb (C50 chain) to 6,000 lb (C100 chain), based on two chains at 30 ft per minute. Speed is “Up to 100 FPM” (Omni chain transfer spec).
Turntable. A turntable rotates a pallet on a section of conveyor. Omni says its powered turntable with CDLR can “Rotate products to change direction but maintain orientation” (Omni Metalcraft).
Pallet dispensers and stackers
A pallet dispenser holds a stack of empty pallets. It releases one at a time onto the conveyor that feeds the palletizer. A forklift loads the stack. A stacker does the reverse. It collects empty pallets into a stack, for example after a depalletizer. See depalletizers.
| Model and source | Rated rate | Stack or load capacity | Notes |
|---|---|---|---|
| Specialty Equipment DTS-3500 | “two pallets per minute” | 60 in. stack standard. Up to 20 pallets with the optional magazine. | Air-operated scissors lift with a “3,500 lb capacity.” Can dispense in three directions. |
| New London Engineering pallet dispenser (sold by Material Flow) | Chain speed “Standard 30 FPM” | “Holds 15–20 GMA or CHEP pallets” | About 60 in. W × 60 in. L × 108 in. H. |
| Columbia LTS-PD | Not listed | Internal upstacker “holds up to 15 pallets” | Part of a load transfer station that swaps pallets. |
Material Flow is a seller, not the maker. Its listing is the public spec we found for that model.
Match the dispenser to your fastest pattern. A full stack should last long enough that a forklift driver can refill it without stopping the line. Columbia lists “Low Pallet Detection” as a standard HL6200 feature. It warns before the stack runs out.
Pallet quality matters here. Broken boards jam dispensers and make loads lean. Use one pallet type per dispenser unless the maker rates it for more. The DTS-3500 is designed for “the same size pallet in a stack.”
Slip sheet and tier sheet dispensers
A sheet dispenser places a sheet on the empty pallet, between layers, or on top. Most pick sheets off a stack with vacuum cups. For what each sheet does, see slip sheets, tier sheets, and caps.
Specialty Equipment’s SSD-1000 uses a “four cup, vacuum assembly that picks-up the sheets.” It holds an 18 in. stack of corrugated sheets. It can place a sheet on a waiting pallet “every two minutes, or when called” (Specialty Equipment). It is pneumatic and runs on an Allen-Bradley PLC (programmable logic controller).
Conventional palletizers often have the sheet dispenser built in. Columbia lists a “Slip / Tie / Cap sheet dispenser” and “Low Sheet Detection” for the HL6200. Robot cells can use a vacuum gripper that picks both cases and sheets.
Pallet inspection
An inspection station checks empty pallets before they reach the palletizer. It sends bad ones to a reject lane.
- SICK’s Pallet Integrity Inspection System uses “four TriSpector 3D laser triangulation cameras to scan the pallet’s loading surface, base, all sides, and internal components.” SICK says it finds “cracks and fractures,” “missing or broken parts,” “twisted blocks,” and “protruding nails” (SICK). SICK does not list a rate on that page.
- Co.Mac’s PALinspect AI uses “3D profilometry and real-time AI classification.” Co.Mac rates it at “100 pallets per hour” (Co.Mac).
Make sure the station’s rated rate is above the number of pallets your line uses per hour.
Layout examples
These are common layouts, not designs for your plant. Your supplier should give you a layout drawing with real dimensions.
| Layout | Flow | Fits |
|---|---|---|
| Single line, straight through | Infeed, palletizer, pallet dispenser, discharge, wrapper | One packing line and one product at a time |
| Two lines, one palletizer | Two infeeds merge, or the palletizer has dual infeeds | Two slower lines that together match one palletizer |
| Robot cell with two pallet stations | One infeed. The robot builds on one pallet while the other is swapped. | Lower rates and frequent product changes |
| Line with wrapper loop | Discharge, chain transfer, wrapper, then pickup | Plants that wrap every load in line |
Leave room to walk around machines and to service them. Plan forklift paths so drivers do not cross the cell to reach the dispenser.
Conveyor safety
ASME B20.1 is the US safety standard for conveyors. ASME says it “applies to the design, construction, installation, maintenance, inspection, and operation of conveyors and conveying systems in relation to hazards.” ASME lists 2024 as the current edition (ASME).
Chain transfers, turntables, and roller drives all have pinch points. Keep these rules:
- Lock out and tag out the conveyor before you clear a jam or reach into it. OSHA’s lockout standard, 29 CFR 1910.147, covers servicing where “unexpected energization or start up” could cause injury (OSHA). Some routine jam clearing may use documented alternative measures instead, under OSHA’s narrow minor servicing exception. See palletizer safety for the limits.
- Guard nip points on chain transfers, turntables, and roller drives. OSHA’s machine guarding rule, 29 CFR 1910.212, names “ingoing nip points” as a hazard to guard.
- Place emergency stops within reach along the run, not only at the palletizer.
- Never walk or stand on a pallet conveyor. Rockwell lists “Person standing on the conveyor” as a palletizer hazard in its palletizer safety guide. Provide crossovers where people need to get across.
- Guard the openings where pallet conveyors pass through a cell fence. Muted light curtains there must stop a person who walks out beside the pallet. See palletizer safety for muting rules.
- Never bypass guards, interlocks, light curtains, or area scanners.
- Treat the palletizer, dispensers, and conveyors as one system in the risk assessment.
For robot cells, guarding, and cobots, see the palletizer safety guide. For the cost of a full line, see what a quote leaves out.
Common questions
A case infeed that accumulates and spaces cases, often with a case turner. Then an empty pallet supply, usually a pallet dispenser. Then a full-pallet conveyor that carries loads to a stretch wrapper and a forklift pickup point. Many lines add a sheet dispenser and a pallet inspection station.
CDLR means chain-driven live roller. Chains and sprockets drive each roller, so heavy pallets move without belt slip. Omni Metalcraft rates its CDLR from up to 1,500 lb per unit load with 1.9 in. rollers to 30,000 lb with 6 in. rollers.
Specialty Equipment rates its DTS-3500 at two pallets per minute. New London Engineering lists a standard chain speed of 30 ft per minute for its dispenser. Rates are rated, not real output. Check that the dispenser keeps up with your palletizer at its fastest pattern.
A machine that picks one sheet off a stack, often with vacuum cups, and places it on a pallet or between layers. Specialty Equipment says its SSD-1000 uses a "four cup, vacuum assembly that picks-up the sheets."
ASME B20.1, the Safety Standard for Conveyors and Related Equipment. ASME lists 2024 as the current edition. Lock out the conveyor under OSHA 29 CFR 1910.147 before you clear a jam or reach in. See conveyor lockout and jam clearing.