Machine Tool Component 3: Magnetorheological Damper

We conceived a damper for a fixture’s plate modal mass. The outer part is attached to the fixture’s plate. The internal part, the electromagnet, is the moving mass of the DVA which is attached to a disk of steel which plays the role of a spring and will provides the required stiffness. A reservoir was dug in the moving mass to receive the MR fluid. Without magnetic field, the MR fluid does not provide contribution; so the damping factor of the DVA is low and its stiffness is brought only by the disk in steel. But when the natural frequency of the fixture’s plate becomes higher, we must increase the damping and the stiffness of the DVA. This is done by applying a current in the electromagnet to generate a magnetic field so that the MR fluid introduces extra damping and stiffness in the DVA.Finally the damper was mounted below the plate for damping its vertical bending model. Some cutting tests were performed comparing the result with and without the DVA. The damper managed to eliminate chatter and obtain nice surface quality in a wide range of cutting conditions.