Preparing the published article.
Understanding Payload Curves and Duty Cycles
Why the same robot performs differently at the edge of its envelope.
The payload curve
A robot's rated payload applies at a defined centre of gravity and distance. Move the load further from the flange, or shift its centre of gravity, and the usable payload drops. Manufacturers publish these limits as curves, and ignoring them is a common cause of premature gearbox wear.
| Factor | Effect | How to check |
|---|---|---|
| Centre of gravity offset | Reduced allowable payload | Payload diagram for your tool |
| Speed and acceleration | Higher dynamic torque | Cycle simulation with real masses |
| Duty cycle | Heat in motors and gearboxes | Compare with rated duty |
| Mounting angle | Changed gravity load | Check installation variants |
Duty cycle in practice
Continuous, high-acceleration work needs a robot rated for it, or a longer cycle with cooling. Cells that run at the limit of the dynamic envelope all day usually show wear first in cables and gearboxes, an expensive way to learn that the margin was there for a reason.