By Liang Wei, Senior Application Engineer, EVST — robotic palletizing and end-of-line cells.
Last updated: 16 June 2026.
Answer first: Size a palletizing robot in three steps — payload first (how heavy is the unit load, across the 3–800 kg range), then reach (can it make the highest, farthest stack position), then rate and gripper (cycles per minute and how you grip a box, bag, can or part). Match those to your line and EVST sizes the cell. Get it wrong and you either overpay for a heavy robot on light cartons or buy one that can’t lift or can’t reach.
Why “which palletizing robot” is really a payload question
Most palletizing mistakes trace back to picking the robot before defining the load. A heavy-duty arm on light cartons is wasted capital; an undersized arm on heavy sacks can’t lift; and a short-reach arm can’t build the top layer of a full pallet. The single most useful thing you can do up front is to put a number on the unit load and the stack — then the robot almost selects itself.
EVST builds palletizing cells across the full 3 to 800 kg payload band, so the goal here is to choose the right size, not the biggest one.
Step 1 — Payload sets the robot size
The unit load is the weight the robot lifts in one pick: the box, the bag, the layer (if you pick a whole layer with a layer gripper), plus the gripper’s own weight. That total sets the payload class:
- Light (≈3–20 kg) — single cartons, small bags, trays. Often a compact or collaborative arm.
- Medium (≈20–120 kg) — case packs, mid bags, small layer picks.
- Heavy (≈120–800 kg) — full-layer picks, large sacks (cement, fertilizer, feed), drums, building materials.
Always size to the real total including the gripper, and leave headroom — running an arm at its absolute limit shortens life and slows the cycle.
Step 2 — Reach covers the tallest, farthest position
Payload alone isn’t enough: the arm has to physically reach the highest and farthest pallet position with the load. Define pallet height (often 1.8–2.4 m built), the number and spread of pallet stations, and any infeed/slip-sheet positions. The vertical-plus-horizontal envelope sets the required reach — and for long lines or multiple pallet stations, a floor rail (7th axis) extends one robot across positions a fixed arm can’t cover.
Step 3 — Rate and gripper finish the spec
Throughput (cases or bags per minute) and the gripper type close the selection:
- Rate decides how fast the arm must cycle, which can push you up a payload class for the structural speed, or toward a high-speed delta for light, fast picks.
- Gripper is matched to the product: vacuum for boxes, clamp/bag-grippers for sacks, fork plates for layers, custom tooling for cans, pails or odd parts. Vision locating handles loosely presented infeed so you don’t need rigid nesting.
Change the product or the stack pattern and you change the program — not the line.
Selection at a glance
| Step | Question | What it sets |
|---|---|---|
| 1. Payload | How heavy is the unit load (incl. gripper)? | Robot payload class (3–800 kg) |
| 2. Reach | How tall and far is the build? | Reach / need for a floor rail |
| 3. Rate | How many picks per minute? | Speed class / delta vs articulated |
| 3. Gripper | Box, bag, can, layer or part? | Gripper type + vision need |
Figures are typical ranges; validate against your real unit loads, pallet pattern and rate.
When a robot palletizer pays off
- Heavy or repetitive lifting that is hard to staff or causes injury (sacks, layers, drums).
- Multiple SKUs or stack patterns where a fixed palletizer is too rigid — a robot changes pattern by program.
- End-of-line throughput that a manual crew can’t sustain reliably.
- Mixed light-to-heavy product families that need one flexible cell rather than several fixed machines.
Where it fits: cross-industry
The same payload-first method sizes cells for food and beverage (cases, shrink packs), building materials (bricks, bagged cement), hardware and metal parts, bagged chemicals and feed, and ceramics. The product changes the gripper; the selection logic does not.
Standards and references that frame the design
- ISO 10218-1 / ISO 10218-2 — industrial-robot and cell safety (guarding, interlocks, risk assessment around the pallet cell and conveyors).
- ISO 9283 — manipulating industrial robots: performance criteria and test methods (pose accuracy / repeatability), the basis for honest placement-accuracy figures.
- Ergonomics / manual-handling limits — the case for removing heavy repetitive lifting from people.
Pre-deployment checklist
- Measure the real unit load (product + packaging + gripper) and the heaviest case.
- Define pallet pattern(s), built height and number of pallet stations.
- Set target rate (picks/min) at peak.
- Choose gripper type per product; confirm vision need for infeed variation.
- Decide single arm vs floor rail for reach across stations.
- Run the cell risk assessment to ISO 10218-2.
Frequently asked questions
What payload do I actually need? Size to the heaviest unit load including the gripper, with headroom — not the average. That total drops you into the light, medium or heavy class within the 3–800 kg band.
Can one robot handle multiple stack patterns? Yes — patterns are programs. Changing SKU or pattern is a program change with the right gripper, not a mechanical rebuild.
Robot palletizer vs a fixed/gantry palletizer? A fixed palletizer wins on a single high-rate SKU; a robot wins on mixed SKUs, multiple patterns, or where reach/flexibility matters. Match the machine to the mix.
How do I reach a tall, multi-station pallet build? Reach class plus, where needed, a floor rail (7th axis) so one robot serves several pallet positions.
Does it handle loosely presented infeed? Yes — vision locating absorbs position variation so rigid nesting isn’t required.
Key takeaways
- Choose by payload first, then reach, then rate and gripper — across the 3–800 kg range.
- Size to the heaviest unit load including the gripper, with headroom.
- Patterns and SKUs are programs; a floor rail extends reach across stations.
- Match robot vs fixed palletizer to your SKU mix and rate.
Talk to EVST about your palletizing cell
Send us your unit load, pallet pattern, rate and product — we’ll size the robot, reach, gripper and (if needed) floor rail, and quote the cell.
→ Contact us for a payload sizing and cell quote.
Or reach us directly: [email protected] · Tel / WhatsApp / WeChat: +86 19381626253
Related reading: welding-positioner selection, robot floor rails (7th axis), and collaborative palletizing.