Intelligent soft jaws for clamping complex geometric surfaces using active-controlled MRF in a 3D-printed TPU-cushion

Abstract

Both additively manufactured and conventional cast parts lack suitable surfaces for precise positioning and repeatable clamping during initial machining operations. Therefore, these parts with freeform surfaces require flexibly adaptable clamping methods. In this project, a clamping system for workpieces with complex geometries was developed, based on the vise principle. The system’s flexible adaptability was achieved by utilizing formable thermoplastic polyurethane (TPU) cushions filled with magnetorheological fluid (MRF), additively manufactured through the fused filament fabrication process. To monitor the clamping status and actively control the clamping force or the frictional force for the workpiece, an intelligent jaw was designed and integrated into the clamping system. In addition to the mechanical components, hardware and software for the control system were also developed. Preliminary validation results indicate that the stiffness of the MRF cushion increases rapidly after applying a magnetic field. Although the range of controllable clamping force is limited, the increased material stiffness allows the MRF cushion to retain its negative form, which results in tighter encapsulation of the workpiece, improved form-fitting contact, and enhanced frictional force. This proof of concept highlights the potential for industrial applications, and further research on this topic is recommended.