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End Effectors - Get A Grip!

Often called "end of arm tooling" (EOAT) or end-effectors, robotic grippers are the physical interface by which the robot performs an operation. Although it seems like only a small portion of the project, end effector design can often define the success of a robotic system. End-effectors can be a tool such as a gripper, a vacuum pump, camera, laser, tweezers, scalpel, blowtorch - just about anything that helps the machine do its job. To ensure successful automation applications, choosing the proper end effector is essential. Straight-forward pick and place applications usually have straight-forward EOAT, and standard, off-the-shelf EOAT components are available. Custom end effectors are necessary when you have difficult-to-hold part or parts needing additional manipulation.

The precision automation experts at DWFritz Automation routinely design custom end effectors that incorporate a camera with a gripper on a single end effector, significantly increasing the accuracy of the operations. These types of custom EOAT are called hybrids. The ability to integrate vision systems with robots has increased the level of precision and accuracy of handling small parts. Handling precise parts means taking into account additional factors. For instance, when part dimensions are measured in millimeters, gravity is the dominant force in pick-and-place operations. However, when part dimensions are measured in microns, other forces might come into play which could cause a tiny part to stick to a gripper instead of dropping into place. Often times, the problem is not grasping micro-parts, it is releasing them. Utilizing a custom end effector that is designed specifically for the project helps eliminate those uncertainties. DWFritz has developed many custom end effectors that have taken into account a diverse set of design requirements and conditions.

Some examples:

10 individually rotating vacuum grippers on a single end effector
                     Custom gripper EOAT for screws
Custom, precision gripper for inspection applications
Industrial robot with custom end effector designed to dispense four different wire types


Factors to consider when determining and designing a custom end effector include:

1. What is the shape and weight of the object to be grasped and/or manipulated?

2. What is the uniformity or tolerance of handled objects?

3. Are the objects’ surfaces smooth?

4. What is the spacing of objects?

5. How will they be oriented and presented?

6. What are placement tolerances?

7. What are grasping forces or pressure limits?

8. Are complementary tools needed?

9. Is compliance necessary for assembling parts?

10. Are there special environmental considerations? (cleanroom, harsh/hazardous, food processing, etc.)

11. Will one end effector do the job, or are multiple needed?