Keep people out or keep robots in?

In recent years, the effectiveness of machine guarding around industrial robots has come into question. While many assume these fences should be able to contain robots completely, the reality is more nuanced.

Several factors must be considered:

Accident historically: Historically, guard fencing was primarily aimed for keeping people out of hazardous areas. However, accidents involving robots often occur due to errors or malfunctions, highlighting the need for comprehensive safety measures. Accidents also occur when people enter the hazard zone where the robot operates.

Risk assessment: Selecting the appropriate safety measures, including machine guarding, requires a thorough risk assessment considering factors such as robot size, speed and potential hazards.

Restricted space: The robot needs generous operating space so it doesn’t collide with the machine guarding during operation or hits a person standing directly in front of a light curtain. A “restricted space” is larger than the “operating space” and smaller than the “safeguarded space”. It serves to ensure that a safety distance will always remain between the safeguard and the “operating space.”

However, one should understand, that principally machien guarding is not meant to hold back stray robots. ISO 10218-2 clearly shows that other measures shall be taken to restrict robot motion. Machinery and system design that relies on guard fencing as a “catch all” is faulty design. Guard fencing is primarily meant to keep people out, not the robot in.