Buying a Used Robot

Used, refurbished and ex-demo are different

Sellers use these labels loosely, so pin down what each one means for the unit in front of you. An ex-demo robot has usually worked at shows or in a showroom and may still carry part of the original warranty. A refurbished unit should have been inspected, repaired and tested by someone who can show you the work done, ideally the maker or an authorised partner. A plain used robot is sold in the state it left its last owner, with whatever wear that involved. Ask for the serial number, the date of manufacture and the history of each unit, then price each category differently, because the risk you carry is different in each case.

Inspecting a used industrial arm

For arms, ask for operating hours, the maintenance log, the controller and software versions, and records of any collisions or gearbox replacements. Then see the robot run. ISO 9283:1998 sets the performance criteria and test methods for manipulating industrial robots, so ask the seller to repeat a positioning test along those lines with a payload similar to yours and compare the result with the original datasheet. Listen for noise from the joints, check cables and dress packs for wear, and confirm that safety functions and emergency stops respond. Find out whether software options and licences transfer to a new owner, because a controller locked to the previous company can cost more to release than the arm saved.

Safety duties still apply second-hand

Buying used does not take safety responsibility out of the picture. In Great Britain, the Health and Safety Executive's guidance on second-hand products says suppliers must make sure equipment is safe for use at work, and that selling it as seen does not remove that duty under section 6 of the Health and Safety at Work etc. Act 1974. It adds that machinery never before placed on the UK market, including grey imports, must go through conformity assessment as if it were new, and that suppliers should provide the original instruction manual or a copy. If you import a used robot yourself, you may be taking on those duties, so check the paperwork before you pay.

Batteries, software and support after resale

Wear on a used robot is easy to see, while fading batteries, expired software and withdrawn support are not. Ask for a battery health report or the cycle count, and price a replacement pack into your offer if the seller cannot provide one. Check whether the robot needs a cloud account, app or subscription to work, and whether the previous owner has released it so you can register it in your name. Contact the maker with the serial number and ask whether it will still service that unit, supply parts and provide updates to a second owner. A maker that declines to support resold units can turn a bargain into a display piece.

Sources and further reading

• Second-hand (re-supplied) products — Health and Safety Executive.
  HSE guidance on safety duties when used machinery is sold on, including grey imports and instruction manuals.
• ISO 9283:1998 Manipulating industrial robots: Performance criteria and related test methods — International Organization for Standardization.
  The test methods behind accuracy and repeatability figures, useful for checking that a used arm still performs.

Common questions

Is a refurbished robot vacuum worth buying?

It can be, if the refurbisher replaced the battery, brushes and filters and offers a warranty you can actually claim on. Check that the app still supports the model and that the unit has been removed from the previous owner's account before you pay.

Do used industrial robots come with a warranty?

Some do, especially when sold by the original maker or an approved refurbisher, but terms are often shorter and narrower than on new robots. Get any warranty in writing, check whether it covers the controller as well as the arm, and ask who will honour it.