Plain talk, with jokes

Fenced or fenceless: the napkin version of a decision the integrator will finish

October 1, 2026 · 4 min read

Every buyer wants the fenceless cell. It is smaller, cheaper to build and friendlier to look at. Sometimes it is also the right answer. Here is how to make the first cut on a napkin, before an integrator makes the real decision in a risk assessment that you do not get to skip.

The short answer

A collaborative robot is one with features that make a fenceless application possible: power and force limiting, speed and separation monitoring, rounded surfaces. Whether your application is collaborative depends on the part, the gripper, the speed, the layout and the people, and a certified integrator decides that in a risk assessment under ISO/TS 15066 and the arm standards. You cannot decide it yourself and neither can a dealer. What you can do on a napkin is predict which way the assessment is likely to go, so you budget for the right cell.

The napkin, five lines

The part. Light, blunt, not hot: a point toward collaborative. Heavy, sharp, hot, or likely to fly if dropped: a point toward fenced. A 25 kilogram case of wine is at the edge. A casting with a burr is a weapon.

The gripper. A soft vacuum pad or padded fingers: collaborative-leaning. A hardened two finger gripper with a steel part in it, or a torch, or a spindle: fenced-leaning, however gentle the arm.

The speed. Collaborative operation limits how fast the arm may move near a person, and that limit is derived from physics, not marketing. If your peak rate needs the arm to move faster than the assessment will allow with people present, the cell is either fenced or it is slower than you need. This is the most common place fenceless dreams end.

The people. Who is near the cell, how often and why. An operator who loads a table every two hours is one situation. A busy aisle where anyone can wander in is another. The brake press unloader in this site's casebook ran unguarded in a busy aisle only after the provincial safety authority approved the assessment, and the company added a zone sensor that drops the robot to 20 percent speed when something unknown enters, voluntarily.

The layout. Six feet of floor between a press and an aisle, as in that same account, is exactly where fenceless earns its place, because a fence would not fit. A corner of a plant with room for guarding gives you the choice, and the choice is often fenced with a fast arm, because fast pays.

What fenceless really costs

A collaborative cell is usually cheaper to build. It is often slower to run, because the assessment limits speed near people, and that trade is the one buyers underweight. A fenced cell with a conventional arm runs at full speed, costs more in guarding and floor space, and is sometimes the better business decision for a line with a real peak. The casebook has both kinds doing well. It also has collaborative arms running behind light curtains and area scanners, which is the common middle: collaborative hardware, with guarding where the assessment demanded it.

The things people get wrong

That the sticker decides. It does not. That a cobot is safe with any gripper. It is not; a knife is a knife at any speed. That fenceless means assessment-free. It means the assessment is more involved, not less. And that the dealer can tell them which way it will go. On this site the concierge will give you the napkin version and then say, every time, that the integrator's assessment is the decision.

Why the napkin is still worth drawing

Because it sets the budget. If your napkin says fenced, price the guarding and the floor space now instead of discovering them in the second quote. If it says collaborative, price the speed limit against your peak rate now instead of discovering it on the acceptance test. Either way you walk into the integrator's visit knowing which conversation you are about to have. Asimov's robots had the laws built in. Yours gets them from a document with a signature on it, and the document is the product.

Describe your part, your gripper idea and who stands near the station to Joe, the concierge on this site. He will draw the napkin with you and tell you which way it leans, and then introduce the people who get to decide.

Related on this site

• Collaborative does not mean fenceless
• Why we will not tell you a cell is safe
• What Asimov got wrong about the factory floor
• What changed when a Quebec fixture maker unloaded a brake press in six feet of floor space
• The ten application guides