Automatic Gantry Palletizer – High-Speed Carton, Bag & Barrel Palletizing Machine
The LWT automatic gantry palletizer is an end-of-line stacking machine that takes sealed cartons, plastic crates, stretch-film packs and barrels from your product conveyor and builds a square, transport-stable pallet load at 20–30 cartons per minute — roughly three times the output of two operators stacking by hand for a full shift. It is built on a heavy-duty welded gantry frame with an adjustable base, a SEW-motor-driven lifting platform and a Siemens PLC control system, so it can sit at the end of a canned food, beverage, chemical or general packaging line without becoming the bottleneck that caps your real capacity.
The Real Cost of Stacking Cartons by Hand
Labor dependency. A manual palletizing station usually needs 2–3 operators per shift for a line running at 20–30 cartons/min. Add shift changes, absence cover and overtime and the station quietly becomes your highest-cost work point.
A line running below capacity. Hand stacking typically tops out at 8–12 cartons/min. If a seamer, labeller or case packer upstream is rated at 30 cartons/min, every carton stacked by hand costs you the difference between design capacity and actual output.
Unstable loads, damaged freight. Hand-built pallets lean, interlock poorly and lose their pattern on curves. The result is crushed corners, stretch-film waste and claims that erode the margin on every container you ship.
Safety and downtime exposure. Repetitive lifting of 10–20 kg cases is a recognized cause of musculoskeletal injury, and a single back injury can take two operators off the line at once.
Why the Gantry Design Holds 20–30 Cartons per Minute
Welded gantry frame with adjustable base. The structural framework is fabricated by welding rather than bolted profiles, which keeps the X-Y-Z carriage rigid under continuous load. The adjustable base lets us level the machine on an existing factory floor without a special foundation.
SEW-driven main lifting platform. A SEW geared motor drives the lifting platform, the component that decides how precisely a layer is placed and how long the machine stays accurate. Loads of up to 1500 kg per pallet are stacked at heights up to 2000 mm.
Double-speed infeed belt and steering mechanism. Infeed runs on a double-speed belt that accelerates the leading carton away from the pack, creating the gap the steering mechanism needs to turn and square each carton before it reaches the layer-forming area.
Sorting box area and roller stack conveyor. Cartons accumulate in the sorting box area until a complete layer is formed, then transfer onto the roller conveyor at the stack position — the layer is always complete before the gantry picks, which is what prevents dropped or misaligned cases.
2.5 m chain discharge and free roller conveyor. Finished pallets leave the machine on a 2.5 m chain conveyor and hand off to a free roller conveyor, so a forklift or AGV can collect without interrupting the stacking cycle.
Siemens PLC with portable HMI. Control is handled by a Germany Siemens PLC with a mobile human-machine interface and portable automatic fault display. Operators can read fault codes at the machine instead of opening an electrical cabinet, and new pallet patterns are selected from the recipe list rather than re-programmed.
Safety protection around the working area. Guarding and safety protection devices cover the palletizing envelope. The machine carries CE certification.
How One Palletizing Cycle Runs
- Infeed. Sealed cartons arrive from the Carton Packaging Machine and are carried into the gantry on a Conveyors System.
- Separation. The double-speed belt and steering mechanism create spacing, turn each carton and square it to the layer pattern.
- Layer forming. Cartons accumulate in the sorting box area until a full layer pattern is complete, then index onto the roller stack conveyor.
- Pick and place. The gantry carriage descends over the layer, grips it, lifts to the programmed height and releases it onto the pallet. The stacking height is set in the PLC recipe up to 2000 mm.
- Pallet indexing. The pallet conveyor advances so the next layer lands on a clean, correctly positioned surface.
- Discharge. The completed pallet travels out on the 2.5 m chain conveyor and free roller conveyor; an empty pallet is indexed in and the cycle restarts without an operator.
Where the Gantry Palletizer Fits in Your Line
Directly after case packing. Cartons that leave the Carton Packaging Machine are sealed, labelled and square — exactly the condition the gantry needs to build a tight load. This is the most common installation for canned food and retort pouch lines.
Downstream of labelling. Where traceability or retail presentation matters, cartons pass the Automatic Labeling Machine before entering the gantry, so the layer pattern is built from fully finished cases.
As the last station of a canning project. Product leaving the Filling Machine is sterilized, cased and then palletized — the gantry is the final automation step that turns a semi-automatic line into a Canned Food Production Line that runs end to end with minimal manual handling.
Typical Applications
- Canned food and retort pouch lines — stacked cartons of canned meat, seafood, fruit, vegetables, corn and beans leaving the case packer at 20–30 cartons/min.
- Beverage and bottled water — plastic crates, shrink-wrapped trays and film-wrapped packs of glass bottles, cans and PET bottles.
- Chemicals, daily care and general industry — barrels, drums, plastic boxes and stretch-film units where a fixed layer pattern is required.
- Bag handling — flat and soft bags of 5–50 kg can be palletized on a matched LWT bag palletizing configuration. Send us your bag weight and dimensions and we will specify the correct layer pattern and gripper.
Frequently Asked Questions
1.Can the pallet size, stacking height and machine footprint be customized?
Yes. The standard configuration handles a pallet of L1200 × W1200 × H150 mm at a stacking height of ≤ 2000 mm, and the pallet size, stacking height, equipment size and capacity are all customized to your product and factory layout during the technical review.
2.Does the machine handle bags as well as cartons?
This gantry palletizer handles cartons, plastic boxes, stretch-film packs and barrels. For flat and soft bags, LWT supplies a matched bag palletizing configuration — send us your bag weight and dimensions and we will specify the correct gripper and layer pattern.
3.What happens during installation and commissioning?
LWT supplies the machine with the palletizing pattern already programmed. Engineers are available to commission on site, and remote video commissioning is offered where travel is not practical. The machine is covered by a 1-year warranty with free replacement parts and on-site service.
4.Which control system is used, and how are faults handled?
The machine runs a Germany Siemens PLC with a portable human-machine interface and automatic fault display, so an operator can read a fault code at the machine and switch pallet recipes without re-programming.
Get a Pallet Pattern Layout and a Firm Quote
Send us four things — your case or bag dimensions, the unit weight, the pallet size you use and the cartons-per-minute you need to palletize — and our engineers will come back with a pallet pattern layout drawing, the matching gantry configuration and a firm FOB or CIF quotation, normally within two working days. If you would rather see the machine before you commit, we can arrange a live video walkthrough of a gantry palletizer running at our Shanghai plant, or put you in touch with an installed LWT line in your region for a reference visit. Every enquiry is handled by an engineer, not a call centre.
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