High Precision Positioning with Ferrofluids as an Active Medium

Study of the influence of ferromagnetic material on the characteristics of an actuator based on ferrofluid and permanent magnets

“…It may be concluded that, according to (8), the force produced by the actuator in Fig. 1 is directly proportional with the coil current, with the circular disc area and with the initial ferrofluid polarization or magnetization.…”

“…is a coefficient that depends on the geometry of the coil and the number of coil windings, the final expression for the magnetic force on the non-magnetic body placed at equal distances from the two magnets is: 0 2ȝ m M F kAM I = (8) Although eq. (8) does not serve to calculate accurately the value of the magnetic force, it has the advantage of simplicity in expression and interpretation, mentioning the main quantities and how they are involved in generating the force.…”

“…The principal drawbacks of the actuator are: stable levitation is obtained for large currents, between 50% and 100% of the current range and the drive force is very small. Positioning systems using different actuator configurations with a nonmagnetic body levitated in a ferrofluid are described by Uhlmann et al [6][7][8]. Several prototypes of precision positioning systems were developed and investigated, the influence on velocity and accuracy of positioning being discussed [8].…”

“…Positioning systems using different actuator configurations with a nonmagnetic body levitated in a ferrofluid are described by Uhlmann et al [6][7][8]. Several prototypes of precision positioning systems were developed and investigated, the influence on velocity and accuracy of positioning being discussed [8]. Such a large scale prototype with optimized magnetic field, using a coil with a ferromagnetic core, a field former (ferromagnetic cylinder) and a ferrofluid with cobalt particles, was able to position loads of up to one kilogram, on small distances of 2-3 mm.…”

Materials in machine tool structures

“…Exemplary applications were presented in Refs. [69,93,273]. Weinert and Biermann developed a damping system for deep-hole drilling using MRF (Fig.…”