Cobots Without a Safety Fence: Safety, Risk Assessment, and ISO/TS 15066 Explained
Yes, cobots may often work without a separating safety fence — but not automatically. Whether fence-free operation is permitted is always decided by the risk assessment of the specific workstation. Here is how collaborative safety works and what you need to watch for.
"Cobots may work without a fence" is one of the most frequent statements — and one of the most frequently misunderstood. The truth is: they often may, but never automatically. It depends on the workstation.
What collaborative safety actually means
A cobot is built from the outset to detect contact and to work with limited force and speed. The most important collaborative operating mode is called power and force limiting: the robot may touch a person, but only with so little force that no injury occurs. How much force and pressure are permissible is described in the ISO/TS 15066 specification, with concrete biomechanical limit values for the different body regions.
The risk assessment decides, not the robot
The decisive point: it is not the cobot alone that determines whether a fence is needed, but the risk assessment of the entire application. It considers not just the arm, but also the tool at the end of the arm (gripper, blade, welding head), the workpiece, the speed, and the environment. Only when this evaluation shows that no unacceptable hazard exists is fence-free operation permitted.
When a guard is still necessary despite a cobot
An additional guard can be required when the tool or workpiece poses a hazard that the cobot does not defuse itself:
- sharp or pointed tools,
- hot parts or processes,
- heavy loads that could cause injury on contact,
- high speeds that exceed the force limits.
In such cases, measures like a laser scanner (which slows or stops the robot when someone approaches) or partial fencing are used. That does not take away the cobot's advantage — it just makes the application safe.
Who is responsible: the CE marking
Responsibility for safety and the CE conformity of the complete cell lies with whoever places the system on the market — as a rule, the integrator who builds the cell. They prepare the risk assessment, implement the protective measures, and affix the CE marking for the overall system. For you as the operator, this means: make sure your integrator explicitly delivers the risk assessment and CE conformity. That is not a detail — it is an obligation.
In short
Cobots may often work without a safety fence — but only once the risk assessment of the specific workstation allows it. ISO/TS 15066 provides the force limits; the integrator provides the risk assessment and CE. Actively ask for both before you sign.
Frequently asked questions
May cobots be operated without a safety fence?
Often yes, but not automatically. Whether a cobot may work without a separating safety fence follows from the risk assessment of the specific workstation. Only when this shows that the robot, tool, and workpiece pose no unacceptable hazard is fence-free operation permitted.
What is ISO/TS 15066?
ISO/TS 15066 is a technical specification for collaborative robots. It supplements the ISO 10218 standards and describes, among other things, biomechanical limit values — how much force and pressure are permissible in contact with a person — above all for the power and force limiting operating mode.
When does a cobot still need a guard?
When the tool or workpiece poses a hazard that the cobot itself does not defuse — for example sharp blades, hot parts, heavy loads, or high speeds. Then a guard such as a laser scanner or fencing may be necessary despite the collaborative robot.
Who is responsible for the CE conformity of the cobot cell?
The party that places the complete system on the market is responsible — usually the integrator who builds the cell. They prepare the risk assessment, implement the safety measures, and affix the CE marking for the overall system.
This article is a general, simplified orientation and does not replace safety engineering or legal advice. The applicable standards, the Machinery Directive or Machinery Regulation, and the risk assessment of your specific workstation are authoritative.