A hybrid manufacturing process for a microgripper using selective laser melting 3D printing and wire EDM

Flexure hinge-based actuators are useful devices that provide precise control over minute manipulations. It is impossible to manufacture the hinge using conventional machining processes because the flexure hinge is thin and has a high aspect ratio structure. Wire electrical discharge machining (wire EDM) is the only machining method for fabricating the device. Wire EDM is a precise method for manufacturing microstructures, but it has the disadvantage of a very slow machining speed. This study proposes a hybrid manufacturing process that uses selective laser melting (SLM) 3D printing and wire EDM to overcome the problem of production speed when manufacturing a flexure hinge-based microgripper. Metal 3D printing alone cannot produce the very thin structure needed for a microgripper. Therefore, the flexure hinges of the gripper were machined using wire EDM after the main structure was manufactured by 3D printing. This not only increased the production speed but also resulted in a more durable gripper. Repeated use of a conventional gripper causes fatigue fracture at the flexure hinge. However, manufacturing the gripper body using SLM metal 3D printing increased the hardness of the product due to the repeated melting and quenching of the material powder. The thermal process increased the fatigue life of the flexure hinge. Therefore, the microgripper manufactured by the proposed hybrid method had a longer endurance life than the gripper machined using only wire EDM. The proposed method is expected to improve the productivity and durability of a variety of flexure hinge-based devices, not just microgrippers.