Automating Machine Tending

Fix how parts arrive and leave

A tending robot spends most of its effort on the parts around the machine, not inside it. Decide how raw blanks are presented: in drawers, trays, stackable pallets or a vision-guided bin. Decide where finished parts go and how inspection samples are pulled out. The more consistently blanks are positioned, the simpler the gripper and programme can be, and the longer the cell can run between refills. Count how many parts one load of the input station holds and compare that with the cycle time to see how long the cell can work without a person. That figure, more than robot speed, often decides the value of the cell.

Design grippers for raw and finished parts

A tending gripper usually has to hold a rough blank going in and a machined part, which may be hot and wet with coolant, coming out. Dual grippers let the robot unload and reload in one visit to the door, which shortens the time the spindle waits. Check that the gripping faces will not mark finished surfaces, and that chips and coolant cannot jam the fingers. Ask how the robot confirms that a part is seated in the chuck or vice before the cycle starts, for example through a clamp pressure signal or a sensor in the fixture. Plan a blow-off or wash step if swarf left on parts could upset the next operation.

Agree where machine and robot rules meet

Two safety standards meet at the machine door. ISO 16090-1:2022 sets safety requirements for machining centres, milling machines and transfer machines, and it applies to workpiece transfer devices for loading and unloading when they form an integral part of the machine. Where the robot is a separate addition, the cell is covered by ISO 10218-2:2025, which deals with integrating industrial robot applications and robot cells, including their integration with other machines. Ask the integrator and the machine builder to agree, in writing, how the door interlock, the machine's safety functions and the robot's safeguards work together, and who validates the combined system.

Prepare the shop for unattended running

The value of tending often comes from running through breaks, shift changes or nights, and that brings new risks. Tool wear, broken tools and chip build-up that an operator would notice need monitoring when nobody is standing there. Ask the machine builder which tool life and breakage detection its control supports, and route alarms to someone on call. Check that fire detection covers the cell if it will run unattended. Write a start-up and shutdown routine, and decide which faults the robot may clear itself and which must wait for a person. Begin with attended running, then extend unattended hours as reliability records build up.

Sources and further reading

• ISO 16090-1:2022 Machine tools safety: machining centres, milling machines, transfer machines, Part 1: Safety requirements — International Organization for Standardization (ISO).
  Safety requirements for machining centres, including loading devices that form an integral part of the machine.
• ISO 10218-2:2025 Robotics: safety requirements, Part 2: Industrial robot applications and robot cells — International Organization for Standardization (ISO).
  Safety requirements for integrating industrial robots into applications and cells, across the whole life of the system.

Common questions

Can one robot tend two CNC machines?

It can, when the machines' cycle times leave the robot enough spare time to serve both and the layout lets it reach both doors and the part stations. Simulate the combined cycle first, because an idle spindle usually costs more than an idle robot.

Should I use a cobot or an industrial robot for machine tending?

Both are used for tending. A cobot can suit low-volume, high-mix work where operators also use the machine, while a guarded industrial arm suits heavier parts and faster cycles. Let part weight, cycle time and the risk assessment decide.