Safety Considerations for Collaborative Machine Tending

Machine tending is the most common application for cobots due to the ease of installation, the high return on investment, and the benefits from the robots’ flexible manufacturing capabilities. Machine tending applications can be misleading in their appearance of safety; in fact, they are one of the industry’s top safety concerns for experts who have completed many inspections and safety assessments.

To maximize safety in automated machine tending applications, manufacturers must use a safety-rated gripper to safeguard against operator injury, and they should also investigate whether the product itself presents any dangers (such as extreme heat or sharp edges).

Other things to consider include:

  • Do other machines need to be safety control-linked to prevent either from operating when the other is in a safety stop condition?

  • Is material handling equipment being used? If so, what are the necessary safety considerations?

  • Since cobots used in machine tending can be moved from machine to machine, how are the safety setting and program validated?

  • Are there warning zones for the operator that will indicate hazards or operation interference?

It is also extremely important to review the entire area for any circumstances where an operator could be trapped or clamped by the robot and surrounding pieces of equipment.

Safety Considerations for Collaborative Material Handling

Figure 3. Collaborative robots provide a highly flexible solution for packaging applications.

Material handling applications that benefit from the incorporation of cobots encompass picking, packing, palletizing, sorting, and more (Figure 3). The wide-ranging use of these applications makes them a more site-specific solution for safety implementation. Operators and other workers are often moving or transporting other materials around the cobot, requiring additional planning to avoid hazardous contact.

Safety-rated grippers are rare in the market at the present time. Currently, manufacturers typically use pneumatic grippers, which require safety considerations for impacts and the loss of power or suction.

Application designers must also investigate whether the product itself presents any damagers like being heavy or containing hazardous material — characteristics that could be especially problematic if the product were to be dropped.

Other things to consider include:

  • Do other machines need to be safety control-linked to prevent either from operating when the other is in a safety stop condition?

  • Since cobots can be moved from application to application, how could this affect validation of the safety settings and program?

  • Are there warning zones for operator that will indicate hazards or operation interference?

As with automated machine tending applications, manufacturers must review the entire area for any circumstances where an operator can be trapped or clamped.

Safety Considerations for Collaborative Assembly

Figure 4. Collaborative robots can work with a variety of end effectors, each of which must be evaluated for safe operation.

Assembly applications employing cobots often involve special tooling and close collaboration with operators while also requiring high-speed operation zones to be present. The extensive variety of custom end-of-arm tooling makes these applications especially complex (Figure 4). If multiple robots are involved, application designers must coordinate the safety solutions for each one.

As with material handling applications, it is important to consider safety requirements for pneumatic grippers, places were an operator could be trapped or clamped, and any products that are heavy or that contain hazardous substances.

Other things to consider include:

  • Do other machines need to be safety control-linked to prevent either from operating when the other is in a safety stop condition?

  • Since cobots can be moved from application to application, how could this affect validation of the safety settings and program?

  • Are there warning zones for operator that will indicate hazards or operation interference?

Summary

Designed with a human collaborator in mind, cobots are generally considered to be safe; however, they still require risk assessments to guarantee safety of human operators throughout their use. It is crucial for manufacturers to consider all the possible hazards associated with hand-guided teaching, including transient and quasi-static contact, as well as what may happen when the robot is involved in an emergency stop.

Designers of automated machine tooling, material handling, and assembly applications must consider all the ways in which the robot would interact with an operator, what aspects of the surroundings might cause clamping or entrapment, and what characteristics of the end-of-arm tooling might pose a risk due to high heat, sharp edges, or other hazards.

If a risk assessment is performed thoroughly and requisite safety measures are implemented, it will ensure the successful efficiency gains of an application and boost performance.

This article was written by Tina Hull, TUV Functional Safety Expert and Product Engineer, and Darrell Paul, Market Manager of Robotics and Motion, at Omron Automation Americas, Hoffman Estates, IL. For more information, visit here .