Now that you have hard guarded your machines where applicable as we discussed in part 1 of this blog, it is important to bring in electrical safety technology to fill the gaps and ensure the work environment is safe for your labor force. Here are some simple guidelines to follow for electric automation safety components and machine design.
Top 5 Machine Design Guidelines for Automation Machine Safety
1) Light Curtains for Open Access into Machine
When efficiency or process do not allow for hard guarding such as fencing, extrusion assemblies with appropriate panels, doors with locks, or other physical barriers, light curtains are the go-to option to prevent machine elements from moving when human operators are loading/unloading materials into the machine. In use of light curtains, it is important to select components that have self-test functions for simulating a blocked beam or self-diagnosis for beam alignment and intensity to ensure proper operation and help notify operators if a light curtain needs cleaning from dust or other contaminants in the environment. The point is that having a light curtain for open access isn’t enough and the light curtain should be sophisticated enough to ensure proper operation 100% of the time, or be able to notify the machine controller of an issue to avoid machine operation if need be.
2) Utilize Area Scanners or Safety Mats to Protect Zones
Many automation solutions can’t be hard guarded due to the process or movement of material with vehicles, overhead cranes, robotics, and other large scale automation. In these cases, it is very important to utilize area scanners and/or safety mats to sense when workers are in a potentially dangerous area or zone. A common mistake with area scanners is not considering them in the design upfront which can create “blind spots” and other potential pitfalls in the design. Safety mats can be a nice solution because not only do they notify the machine, the worker physically steps on a mat which lets them know they are in an area where safety is paramount.
3) Redundant Safety with Safety Relays
Avoid using standard relays (non-safety rated) due to cost and reach for approved PLe/Safety Category 4 (EN ISO13849-1) safety relays. Safety relays provide redundant circuitry to ensure if one channel fails, the safety equipment will still operate with the second channel. These relays also come equipped with intelligence and can notify the machine controller if one channel fails so the device can be serviced or replaced.
4) Safety in Robotic & Motion Control Devices
Similar to recommendations with hard guarding, motion and robotics are no different. When in doubt, select motion control and robotic solutions that have safety certifications and features built-in as standard specifications. There are lots of products that have these features and typically will not significantly affect the cost of the overall machine design. Certifications such as IEC 61508 SIL3 and safe torque off help specify components that reduce machine risk and increase overall reliability. With robotics, the “collaborative” innovation has brought even more safety technology to not only collaborative robots, but also industrial robots and motion control/servo systems with the ability to detect collision to either stop or reduce current/torque applied to the servo motors in order to prevent/eliminate damage or harm. Combining “collaborative” with a feature like “safe speed” allows the machine to reduce speed to safely allow operators to perform some type of work without completely stopping the machine.
5) Specify Components & Equipment for the Environment
Just like physical hard guarding, electrical/motion/robotic components must also factor in to the operating environment to ensure safety. Temperature is always a big factor to ensure proper operation of electronics, so make sure the ambient temperature of the operating environment is factored into the sizing and selection of any of these components. Additionally, any other dust, contaminants, fluids which could either damage components or prevent proper operations should be reviewed and factored into the selection of every component.
Mechatronic Solutions is a high-tech automation distributor with mechanical and electrical design engineers to help create machine safeguarding solutions, including aluminum extrusion assemblies and safety fences with light curtains, area scanners and other electrical safety components for motion control and robotic automation systems. With its mechanical and electrical value-added assembly shop, Mechatronic Solutions can also assemble a large variety of complex machine guarding structures including robotics, safety light curtains, UL 508A electrical panels, motion control, actuators, pneumatic components and more.
Contact us to have a Mechatronic Solutions' design engineer help design an appropriate safety solution specific to your machine and need.