Design of eddy current dampers for vibration suppression in robotic milling

The milling robot normally has a low stiffness which may easily cause chatter during machining. This article presents a novel eddy current damper design for chatter suppression in the robotic milling process. The designed eddy current dampers are installed on the milling spindle to damp the tool tip vibrations. The structural design and the working principle of the eddy current dampers are explained. The magnetic flux density distribution and the magnetic force generation of the designed eddy current damper are analyzed with the finite element method. The tool tip dynamics without and with eddy current dampers are modeled, and the damping performance of the proposed eddy current dampers in the robotic milling process is verified through both simulations and experiments. The results show that the peaks of the tool tip frequency response function caused by the milling tool modes are damped significantly, and the stable depth of cut is improved greatly with eddy current dampers.

Current and Future Manufacturing of Chest Orthoses, Considering the Case of Osteogenesis Imperfecta

The present paper aims at discussing the current manufacturing processes of chest orthoses, considering patients affected by Osteogenesis Imperfecta (OI) and a possible future scenario. OI is a genetic disease caused primarily by the genes responsible for collagen production. One of the most common symptoms among the groups of living subjects affected by OI is scoliosis, the abnormal deformation of the spine curvature. The non-invasive treatments for realigning the spine consist of both physical exercise and use of chest braces. The latter are strongly patient-dependent devices; thus, the level of customization is high. The production processes can be classified in: traditional, modern and research process. The first one consists of a sequence of manual operations on plaster casts and final orthoses. The modern process integrates CAD/CAM systems for the first phases of virtual 3D modeling and the automation of the cast production using milling robot, but maintaining the second part of the process. The research process considers the introduction of polymer Additive Manufacturing (AM) in substitution to the thermoforming. Advantages and disadvantages related to each process are discussed in relation to the OI problem.

Design and Implementation of CNC Milling Bot for Milled Circuit Board Fabrication

This research paper presents an alternative way to fabricate a Milled Circuit Board (MCB) with the help of a Computer Numerical Controlled (CNC) milling robot. Printed Circuit Boards (PCB) are one of the most widely used control modules in electrical and electronic industries. In this research paper we propose a computer controlled milling machine which can be used for quick fabrication of double layered PCBs called MCB where a user wants to test the circuit without the need to wait for the conventional PCB fabrication. The end effector of the CNC milling machine has the provision to move in 3 axes-x, y and z in accordance with the input received from the controller. DipTrace, an EDA/CAD software is used for creating the schematic diagram for the milled circuit boards. The design to be engraved on the copper clad board is uploaded to a software called CopperCam, where it can be converted to G-code files after making the necessary modifications. These G-code files are then uploaded to the CNC machine using the software Universal G-code Sender, thus enabling the microcontroller to direct the rotation of motors and coordinate the movements of the end effector so as to engrave the board design on to a copper clad.