ISO/TS 15066 in Plain English: Force Limits, Tooling, and Real-World Examples

When collaborative robots first entered factories, many engineers assumed that “safe collaboration” simply meant running robots slower. In reality, true safety is governed by measurable physical limits — and that’s what ISO/TS 15066 defines. This technical specification translates theory into numbers: how much force, pressure, and speed a cobot can apply without harming a human. Here’s a practical breakdown, free from jargon.

What ISO/TS 15066 Covers

ISO/TS 15066 supplements ISO 10218 by setting quantitative thresholds for human–robot contact. It defines acceptable force and pressure limits for 29 body regions, measured under controlled test conditions. It also explains how to test, validate, and document compliance — essential steps for any manufacturer or integrator deploying collaborative robots.

The goal is not to eliminate all contact, but to ensure any contact is non-injurious. These values form the benchmark for collaborative modes like Power and Force Limiting (PFL).

How Force and Pressure Limits Work

Each part of the human body has a different tolerance. For example:

• Hand and arm: higher limits, typically up to 140 N transient force.
• Head and face: far lower — around 65 N transient force.
• Joints and soft tissue: critical areas; should be avoided entirely.

When designing collaborative applications, always consider the contact type (transient or quasi-static) and the contact area. The same force applied by a sharp edge vs. a rounded surface produces very different pressure values.

Tooling Design for Safety

The end-effector often determines whether a cobot stays within safe limits. To meet ISO/TS 15066:

• Use rounded, padded, or soft tooling materials.
• Eliminate sharp corners and protruding bolts.
• Use force sensors or compliant mechanisms when possible.
• Design gripping surfaces to release parts safely during collision.

Tool mass is another key variable — a lightweight gripper at low speed may pass, while the same motion with a heavier tool could exceed safe limits. Always verify combined kinetic energy.

Measuring and Validating Compliance

Validation requires measurement. Specialized force and pressure measuring devices simulate human tissue to verify that contact values stay below ISO/TS 15066 limits. Common procedures include:

1. Measuring contact forces at different speeds and payloads.
2. Checking compliance for each robot posture and path.
3. Documenting results in the project’s safety file.

Manufacturers must retain this documentation — it’s proof of compliance during audits, insurance checks, or CE/UKCA certification processes.

Real-World Example: Packaging Line Deployment

One European SME integrated a cobot for packaging cosmetic bottles. During validation, initial readings exceeded 180 N due to tool weight. After redesigning the gripper with lightweight composite material and adding torque limits in software, contact forces dropped to 90 N — fully compliant with ISO/TS 15066. The project passed inspection and improved throughput by 18 %.

Another Example: Shared Welding Station

In a collaborative welding setup, the cobot operates only while the operator is behind a defined zone. Safety scanners enforce Speed and Separation Monitoring (SSM), switching to PFL mode only during part handover. This dual-mode design reduced safety stops by 30 % while maintaining full compliance.

Best Practices Checklist

• Base all safety settings on actual force measurement, not guesswork.
• Design tooling first, validate early, and iterate before production.
• Train operators to recognize the meaning of visual indicators (speed, mode, warnings).
• Revalidate whenever tool mass, speed, or workspace boundaries change.

Related Articles

• Cobot Safety in 2025: A Practical Playbook for Fast, Compliant Deployments
• From Risk Assessment to Run Time: How to Make Collaborative Robots Truly Safe
• 10 Cobot Safety Mistakes SMEs Still Make — And How to Fix Them
• Cobot Cells That Scale: Modular Fencing, Light Curtains, and Safe Sensors

Quick Q&A

Q: Does ISO/TS 15066 replace ISO 10218?
A: No. ISO 10218 defines general robot safety; ISO/TS 15066 adds collaborative-specific thresholds and testing methods.

Q: How do I know if my cobot meets force limits?
A: You must perform physical tests using a compliant measuring device — software limits alone aren’t sufficient proof.

Q: How often should compliance be rechecked?
A: At least annually or whenever significant changes in tooling, speed, or workspace occur.

Conclusion

ISO/TS 15066 gives manufacturers a practical, measurable way to make collaboration genuinely safe. By applying its force and pressure limits, validating real-world contact, and designing smart tooling, integrators can ensure cobots work safely — not just theoretically, but every shift, every day.