A Critical Review of Releasing Strategies in Microparts Handling

In the last ten years, various grasping principles and releasing techniques suitable for microassembly have been hypothesised and successfully tested. Since in microdomain adhesion forces overcome the gravity one, new grasping principles have been exploited to grasp microparts. Unfortunately, in microassembly the most critical phase is not to grasp a micropart, but to release it. Therefore, the development of releasing strategies plays a fundamental role in the entire assembly cycle. This paper proposes a scheme for classifying many releasing strategies developed in the microassembly field, provides a map of interesting grasping-releasing couples and analyses in detail one of the most reliable grasping principles (i.e. capillary gripper) and the related possible releasing strategies. Finally, a procedure for the selection of grasping and releasing strategies on the basis of the components to be handled and on the boundary conditions is provided.