Robotic grippers are one of the most common types of end-of-arm-tooling devices integrated with robots. They give industrial robot to capability to handle, manipulate, and lift workpieces. Robot users have three main types of grippers to choose from when it comes to automating part handling processes, these include angled, finger, and parallel grippers.
Parallel style grippers are the most widely used gripper type for robotic automation. They feature a two-jaw design that mostly varies among the fingertip construction as this part of the device typically needs to be customized toward specific object types. Parallel grippers grasp parts when the two sides close parallel to one another around a workpiece. The workpiece is released from the gripper when both sides simultaneously open and let go of the object. For example, a FANUC M-20ia integrated with a parallel gripper for its EOAT will move and lower its arm to the workpiece. The parallel gripper then closes both sides to secure the workpiece so the M-20ia can then move the part.
Parallel grippers are commonly utilized for pick and place applications. They are best suited for working with parts that are repeatable and have pre-determined geometries. This means these devices are designed to handle specific part shapes that will remain consistent during the manufacturing process. If your production process involves the transferring of several different part types, a parallel gripper would not be recommended. They are also not suited for handling irregular part shapes or circular parts because they only have two points of contact. For instance, a FANUC M-710ic fitted with a parallel gripper can easily handle the transferring of boxes to a conveyor because of their symmetrical and simple shape.
There are two subcategories of parallel grippers. These categories are based upon the power sources used which can either be pneumatic or electric. Pneumatic parallel grippers are powered through compressed air. With this type an air supply is connected to the robot gripper. When air is fed through the intake valve pressure is applied to the device’s piston. The piston then moves and applies force causing the sides of the gripper to close around an object. When the air pressure is released the piston moves back to its original position, releasing its force on the gripper allowing both sides to open and let go of the object. The ABB 2600-20 is an example of a robot that is commonly integrated with this type of EOAT. The key to successful operation is determining the proper amount of air to apply and may require several tests in order to best determine this.
Electric parallel grippers, as the name implies, are powered through electric motors. Servo motors are commonly used with these devices, but other motor types can also be used. A parallelogram mechanism translates the motor rotations into a straightforward motion to open and close the end-effector. Electric grippers can allow for adjustments to both force and speed. They can also allow for more versatile finger designs, making them more adaptable to a wider range of part types. The Motoman HP20 is ideal for operating an electric parallel gripper.