Get a Gripper - Cobots and end of arm tooling considerations

Get a Gripper

Cobots and end of arm tooling considerations

As many manufacturers look to greater production flexibility, the demand for collaborative robotics becomes compelling.

A collaborative robot, or ‘cobot’, is an easily operated machine that is designed to work safely with, or in close proximity to, human workers without the need for additional safeguarding. Cobots are designed without sharp corners, exposed motors and pinch points; and, if properly configured, they have the ability to work free from vision systems, laser scanners and fencing.

For a robot using any of these four collaborative modes (Monitored Stop, Speed and Separation Monitoring, Power- and Force-Limiting, and Hand Guiding), end users should take care when selecting a compatible and safe gripper for their application.

From ease of programming to quick return on investment, end users have many motives for choosing collaborative automation. Regardless of these reasons, however, collaborative robots must be equipped with the appropriate end-of-arm tooling to fulfill a specific task.

The Importance of End-of-Arm Tooling

Without the appropriate end-of-arm tooling a robot will do little to add value to the production process. Moreover, for an application to preserve it’s collaborative status, particular attention must be given to the end of arm tooling, or specifically, the end effector. While a collaborative robot may be safe, the entire robotic system must be considered carefully when designing and commissioning a system that will pass a risk assessment.

Example – if a collaborative robotic arm is equipped with an end effector that features a knife or a sharp-edged tool (or even picks up a part that could cause harm), this is by definition “unsafe”, and the robotic cell is still dangerous to human workers. Therefore, manufacturers should always participate in a risk assessment to ensure the use of a cobot does not compromise worker safety and application integrity.

Concepts to Consider when Choosing EOAT for Collaborative Operation

Collaborative robots present uncommon challenges for EOAT that can be unexplored territory to end users familiar with conventional robotic EOAT methods. An accurate risk assessment should be able to provide precise insights for guiding companies through the following concepts to consider when choosing an end effector for a collaborative robot:

ISO Safety Standards

While worker safety is a primary concern with any robotic application, there are more stringent requirements for collaborative systems designed to work with or near, human workers. Every collaborative application requires a specific type of tool that is compliant with all ISO safety standards (ISO 10218-1, ISO/TS 15066, ISO 13849-1 PLd Cat 3).

Process Needs

Selecting the proper end effector for a collaborative application is primarily based on an end user’s process needs, and depending on the application, EOAT can be electric, pneumatic, and in some cases hydraulic. Factors such as weight, speed, accuracy, complexity and power consumption should all be considered when selecting an end-of-arm tool.

Gripper Technology

From simple gripper configurations, such as a two-jaw parallel design or suction cup, to complex gripper variations, such as a force feedback electric gripper, there are a host of gripping solutions available to end users. While this abundance of options can be overwhelming, a good rule of thumb for decision makers to follow is to keep the technology as simple as possible.

Process needs and part size usually determine the type of end-of-arm tool required to meet production demands, and in most cases depending on the application, an electric or pneumatic gripper can be used. A cost/benefit analysis can help determine if a pneumatic or electric device is more advantageous over the robot system’s lifecycle.

Electric Grippers offer flexibility and precision, potentially giving end users the ability to program the gripper for various jaw travel lengths. Likewise, electric grippers can provide control over velocity or force. These are ideal for applications where part size and shape may change on a regular basis. Keep in mind that electromagnetic grippers may be the best solution for parts containing ferrous materials.

Typically, more expensive at the start than their pneumatic counterparts, electric grippers can save on cost and complexity, especially if it allows the system to eliminate an air compressor.

Pneumatic grippers typically offer simple open and close jaw position, compared to the programmability of electric grippers. Depending on the input air pressure provided, pneumatic grippers can adjust their grip force to varying degrees. Often designed for one product, these grippers are well-suited for applications where part size and shape remain consistent.

Don’t forget that pneumatically operated suction cups or magnetic grippers may also be a viable option depending on the weight and composition of your part. While less expensive upfront, pneumatic grippers could add additional cost if you don’t have easy access to compressed air.

End Effector Supplier

Depending on application needs, there are end effector suppliers that specialise in certain areas of gripper technology (i.e., vacuum components and clamping systems). When choosing a gripper supplier for collaborative systems, decision makers should ensure that the gripper meets or exceeds all ISO collaborative requirements.

In Summary

Not all processes are applicable to collaborative robots, and not all end-of-arm tooling is safe to work in a collaborative manner. For this reason, a risk assessment of the overall application solution should be done to determine the potential hazards, and to ensure the proper devices are used while the appropriate procedures to mitigate any risk are followed.

Once this has been accomplished, end users can confidently move forward with selecting end effector technology for collaborative operation. From simple gripper configurations to complex end-of-arm variations, there are a plethora of gripping solutions available.

While a large selection of electric or pneumatic options may be overwhelming to end users, a good piece of advice for decision makers to follow is to keep it safe and simple.

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