Robotic Bag and Sack Palletizing
Stacking 25 and 50 kg bags by hand is the job most plants automate first. It is heavy, repetitive and the labour turnover is high — and at two or three bags a minute over a full shift, the physical load on an operator is the limiting factor long before the bagging machine is.
A robot palletizer takes the bag from the discharge conveyor, orients it to the pattern and places it on the pallet. Pattern, layer count and pallet size are parameters, not mechanics: changing from a 5-bag to a 6-bag layer, or from one bag size to another, is a program selection rather than a rebuild. That matters in plants that fill several products on one line.
Which industries use it
Cement and dry mortar, mineral fertiliser, flour and sugar, animal feed, seed, salt, plastic granulate and mining concentrates. Anything filled into a valve or open-mouth bag and stacked on a pallet or slip sheet.
Choosing the robot
Two figures decide it, and both are usually underestimated.
Payload. Size it on the bag plus the gripper, not the bag. A bag clamp or vacuum head for 50 kg sacks is itself 25 to 45 kg, so a 50 kg bag needs a robot rated near 100 kg, not 50. Double-picking two bags at once — common on high-rate lines — doubles that again.
Reach. Measure to the top corner of the finished stack, not to the pallet. A 1.8 m column on a 150 mm pallet plus the height of the gripper takes more reach than most first estimates allow.
- RP24-130 — 130 kg, 2485 mm. The standard choice for single 50 kg bags with a clamp head.
- RP32-180 — 180 kg, 3130 mm. For double-picking, tall stacks, or two pallet positions served from one robot.
- RP18-25 — 25 kg, 1885 mm. Small bags, 10 to 15 kg, and light cartons.
- RP15-15 — 15 kg, 1530 mm. Compact cells and light packs.
All four are four-axis machines. The parallelogram linkage holds the load level without wrist rotation, which is both faster and more stable for stacking than a six-axis arm. Where the bag must be tilted or presented at an angle — some slip-sheet and interlayer operations — a six-axis handling arm such as the RA26-220 or RA28-360 is used instead.
What else the cell needs
The robot is one line item of five. Budget for the bag gripper (clamp, vacuum or fork type, chosen by bag material and whether the bag is deaerated), the infeed conveyor and bag flattener, pallet dispenser and empty-pallet magazine, safety fencing with an interlocked pallet exit, and — where the stack is shipped by road — a stretch wrapper.
Dust is the other design factor. Cement and fertiliser plants need the robot and its cabinet placed and protected accordingly; tell us the product and the fill rate and we will specify it with the factory.
Get a quotation
Send us the bag weight and dimensions, bags per hour, pallet size and stack height, and we will come back with a robot model, a gripper proposal and a price. Drawings are not required at this stage.
