Attractive price, unknown history
A used robot listing gives the brand, model, year and perhaps an hour count. What it leaves out matters more: what job did the robot do, how worn are the gearboxes, was it serviced on time? A robot from a welding line and a robot that moved light parts are not in the same condition, even if they were built the same year.
The trouble usually shows up after the cell is built and in production. Backlash grows on one axis, the cable harness breaks at the wrist, a controller board fails and no replacement can be found. The low purchase price is gone with the first long stoppage.
The real risks of a used robot
- Unknown operating hours: if the controller keeps this record, we read it. If it doesn't, or it has been reset, only an inspection tells you the robot's condition.
- Worn gearboxes: backlash, noise under motion and metal particles in the oil are signs of gearbox wear. A gearbox replacement is one of the most expensive repairs on a robot.
- Cable harness wear: the cables running between axes fatigue with motion, especially at the wrist axes. Intermittent encoder or motor faults often start here.
- Older controller generation: ABB S4C+ and the KUKA KR C2 generation are out of production; new parts are scarce and expensive. IRC5 is now being phased out too: ABB continues to support it, but its current generation is OmniCore. The controller generation decides how many more years parts will be available for the robot.
- Missing software options: an option you need (for example safety-rated zone monitoring or an application package) may not be enabled on that controller. Adding it later costs extra.
- Missing documentation: operating and maintenance manuals, spare-part lists, program backups and calibration data often don't come with the robot.
The CE mark comes with the cell, not the robot
Installing a used robot in a new cell creates a new machine. The cell as a whole needs a risk assessment, a designed safety circuit and a CE mark at handover. That doesn't change because the robot is used. Older controllers may need additional safety hardware for the safety circuit to meet current requirements.
How we take the risk out
Before the robot goes into a cell, we measure its condition:
- Inspection: backlash measurement on every axis, noise and vibration checks while jogging each axis, and a read-out of the controller's fault history.
- Gearbox oil and grease: we check the condition and change it to the maker's interval.
- Battery and cables: where the robot has a backup battery for its position memory, we replace it. We check the cable harness and connectors and replace them where needed.
- Backups: the robot's existing programs, system and calibration data are backed up.
- Refurbishment: replacing worn parts found in the inspection.
- Spare-part plan: we list the critical parts for that controller generation and agree with you which ones should be on your shelf. We supply new and used parts with warranty for ABB, KUKA and other brands, and we repair and test robot boards and drives in our own workshop.
One limit, honestly: an inspection can't tell you exactly how much life a gearbox has left. It shows the signs of wear. That is why, on a critical line, we suggest putting long-lead parts into your spare-parts plan from day one.
If the controller is very old, there is another route: keep the arm and replace the control cabinet with a current generation. Where the maker offers an upgrade path for that arm, we do this too.
Who sources the robot?
There are two cases. If you have found a robot, we look at it together before you buy. If you'd like us to supply the robot as well, ask us. Either way, we agree the warranty terms in writing at the start.
For robots you are taking out of another plant, our robot cell relocation service covers the same process: dismantling, transport, re-installation, re-mastering the axes and a safety check.
Questions buyers ask
How much does a used robot save? It depends on the robot's age, controller generation and refurbishment needs. We add inspection and refurbishment cost to the robot's price and set it side by side with a new robot.
Will an older robot run as fast in a new cell? Payload and reach stay the same. Motion planning on older controllers can be slower. We check the cycle time in simulation using that robot model.
Who will maintain it? We can take on periodic maintenance for the robots we commission.