How to prevent unexpected machine starts with “full body access” in robot streets
The ISO standard for safety requirements for industrial robots (ISO 10218: 2011) has been adopted in many regions, including the USA (RIA 1506-2012), Canada (CSA Z434 – 2014), Australia (AS 4024.3301 / 2: 2017) and India (IS 14530: 2019). This is good news for everyone involved in the design and manufacturing, as well as for users.
Full-body access is a situation where the entire body of a person can enter the secured area. Robot cells are often provided with a large (unclear) shielded area, which means that full-body access must be considered. ISO 10218-2: 2011 provides very clear guidelines to prevent an unexpected start-up of a robotic system when an operator is in the protected area.
First, the start and reset controls must be in a clear and unobstructed place in the protected area. This may seem simple, but it is often difficult to achieve. This is due to the large surfaces, where machines or additional equipment obstructs the view. Another cause is dark and dusty environments.
If the first option is not feasible, or if the risk assessment requires it, other protections should be used to avoid an unexpected restart.
Examples include: locking the door, in the open position (with a Trapped Key Interlock system, with security keys or containment protection), arrangements for isolating and locking dangerous machines within the secured area. Or a reset facility with a time delay (so that a visual check can take place in the protected area).
Only if no other means are possible to prevent an unexpected restart, an audiovisual pre-start warning can be used (e.g. signal lamp with siren). This must be combined with an identifiable and accessible emergency stop device, so that when someone is warned by the signal, the emergency stop can be activated.
Unique Safety Products has a wide range of products to help you reduce the risk of an unexpected machine start. These include secure radar scanners, fully mechanical Trapped key interlocks and tongue-actuated safety key interlocks. These can be added to existing systems without the need for control modifications.
Means to avoid an unexpected start:
1. Create a clear and unobstructed view of the protected area from the start/reset device
2. Use presence sensors to detect operators in the protected area
3. Provide other protective measures:
- Means to isolate and lock down hazardous equipment
- Measures to lock a door when open
- Extra reset facilities with time delay in the protected area
4. Audiovisual pre-start warning signal that can be heard from the inside and gives enough time to go outside
We also have a selection of safety switches and safety interlocks available on our web shop www.machinesafety-shop.com.