Preparing the published article.
Scoping a Robot Cell: Payload, Reach and Cycle Time
The three numbers that decide whether a robot can do the job before any quote is written.
Measure payload honestly
Rated payload is not usable payload. Add the end effector, the workpiece, any fixture carried by the robot and a margin for tooling changes. A robot quoted at its rated payload will run slow and wear out early; the practical rule is to stay near 60-70% of the rated figure for a cycle that repeats all day.
Reach includes the gripper
Reach is measured to the tool flange. Subtract the tool length, then check the worst-case position in the cell — not the average one. Robots lose accuracy near the edge of their envelope, so plan the motion path to keep the critical operations inside the middle of the working volume.
| Parameter | How to measure | Common mistake |
|---|---|---|
| Payload | Workpiece + gripper + cabling + margin | Using the workpiece weight alone |
| Reach | Flange-to-target at the furthest point | Forgetting the gripper length |
| Cycle time | Sum of moves + grip + process + settle | Ignoring I/O and handshake delay |
Cycle time is a system number
Add the time the machine spends waiting for a signal, the time the operator needs to present a part, and the settle time after a fast move. Simulation is useful for the robot motion; the handshakes are usually what break the takt time in the real cell.