CNC machine tending in a 20-person shop wasn't automatable until the robot could move between machines
A dedicated tending cell made sense next to a machine that ran one part all year. A job shop with six machines and a hundred part numbers could not justify a fixed robot at any of them. Collaborative arms on wheeled carts, with standardized workholding and automatic doors, made one robot serve several machines and many jobs.
The short answer
Machine tending is the first robot in most small shops today, and it was almost nobody's first robot fifteen years ago. The difference is not the arm. It is that a collaborative arm can sit on a cart with its own gripper and part table, be rolled to whichever machine needs an unattended shift this week, and be set up by a machinist in an afternoon. Combined with automatic doors on the machines and workholding that locates parts consistently, the cell pays back on spindle hours gained rather than on a single part number.
Why this job resisted automation for so long
A traditional tending cell is bolted to the floor in front of one machine, fenced, and integrated into that machine's controller. It is excellent for a production part that runs for years and useless for a shop whose work changes weekly. The programming needed a specialist, the fixturing was custom, and the economics only worked if the machine ran near capacity. Small shops had none of those conditions. They had six machines each waiting on an operator part of the day, a second shift they could not staff, and a different job on every one of them.
What changed
Collaborative arms made the fenceless cart possible, subject to a risk assessment. Grippers became modular and quick to change. Tablet-based programming let a machinist teach a pick and a place without writing code. Machine tool builders started offering automatic doors and robot-ready interfaces as options rather than custom engineering. And the shop floor habit of standardizing workholding, so a family of parts loads into the same vise or chuck the same way, turned out to be the single biggest enabler, because a robot that puts the part in the same place every time needs the fixture to accept it the same way every time.
The casebook on this site carries published examples: a 25 to 50 person machine shop that filled a night shift with one cobot, an optics shop with two rail-mounted cobots tending three machines, and another 25 person shop running its Haas overnight with a vision-guided cobot. The common pattern is a few machines, a cart or rail, and parts presented on a grid.
What it looks like now
A collaborative arm on a cart or pedestal, a gripper or two, a presentation table or drawer system that holds a shift's worth of blanks on a grid, an automatic door or a door opener on the machine, and a connection so the robot knows when the cycle is finished. The operator sets up the job, loads the table, and goes home or goes to another machine. The planning ranges on this site's machine tending guide cover equipment and integration separately, because the door, the workholding and the interface are often where the money goes.
What still disqualifies a shop
Parts that cannot be presented consistently, or that need deburring and inspection between operations the robot cannot do. A machine without an automatic door and no practical way to add one. Cycle times so short the robot cannot keep up, or so long that one operator could tend four machines by hand anyway. And the classic error: automating the machine that is easiest to automate instead of the one that is the constraint.
How to find out if yours is automatable
List your machines and estimate how many hours a week each one sits with the spindle stopped waiting for a person. Multiply by your shop rate. The machine with the biggest number is the candidate, whether or not it has the easiest parts. Describe that machine and its parts to Joe, the concierge on this site. It will ask about the door, the workholding and the part family, and give you a preliminary read on the cell and what an integrator will want to verify.
Related on this site
- CNC machine tending
- CNC lathe tending
- Grinder and saw tending
- Robots for machine shops
- Who will run the cell
The robot is the easy half. Automatic doors, consistent workholding and a part presentation table are what make a job shop tending cell actually run unattended.
Put it to the test on your own job
Tell Joe what you are running and he will apply this to your numbers, including telling you when a robot is the wrong answer.
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