Design of a passive alternative for long stroke linear aerostatic stages based on ferrofluid bearings

The objective of this research is to demonstrate the capability of a long stroke linear ferrofluid (FF) stage. This stage is a passive alternative to existing linear aerostatic stages and can be used in low loaded CNC devices, pick and place machines, microscopy or scanner applications. To compete with aerostatic stages the bearing must be...

Fundamental Electromagnetic Configuration for Generating One-Directional Magnetic Field Gradients

In this article, electromagnet layouts are presented, which generate a magnetic field with a magnitude gradient that does not vary significantly in a horizontal plane but decreases monotonically with the vertical height above the magnet. Such a one-direction magnetic field gradient is a specific requirement for magnetic density separation ...

Optimum Coil-System Layout for Magnet-Driven Superconducting Magnetic Density Separation

This article discusses the optimum layout of coils of a superconducting magnet system for magnetic density separation (MDS). MDS is a novel separation technology that combines a vertical magnetic field gradient with a ferrofluid to separate mixtures of non-magnetic particles based on their mass density. The MDS process can separate more than...

Magnetic fluid bearings & seals: Methods, design & application

The bearing and the seal are two commonly used tribological components since nearly all moving machinery relies on them for proper operation. Even a small improvement in these components can have a big impact on both the market and the environment. The two main problems of these components are wear and friction. In addition, seals suffer from...

Smart magnetic fluids: Controllable distributedfluidic actuation

This thesis is centred around the problem that heart failures become more common when other dis-eases could be treated better. Although surgery could fix the immediate effects of heart failures, therecovery after the surgery is hindered by the heart not being able to pump enough blood. There aresolutions available but they are not implemented...

Total magnetic force on a ferrofluid droplet in microgravity

The formulation of the total force exerted by magnetic fields on ferrofluids has historically been a subject of intense debate and controversy. Although the theoretical foundations of this problem can now be considered to be well established, significant confusion still remains regarding the implementation of the associated expressions....

Ferrofluid rotary seal with replenishment system for sealing liquids

Ferrofluid rotary seals are mechanical contact-free magnetic liquid seals that are characterised by their simple structure, low friction and ability to hermetically seal. Although ferrofluid rotary seals for sealing vacuum and gases are part of a well established industry, the sealing of liquids has not been implemented yet. Literature learns...

Capillary rheometer for magnetic fluids

Magnetic fluids have been around since the 1940s. They come in different forms: magnetorheological fluids (MR fluids) and ferrofluids. MR fluids characterise themselves by having a large change in viscosity under the influence of a magnetic field. Ferrofluids have a significantly smaller change in viscosity, however ferrofluids are colloidal...

Ferrofluid Rotary Seal with Replenishment System for Sealing Liquids

Ferrofluid rotary seals are mechanical contact-free magnetic liquid seals that are characterised by their simple structure, low friction and ability to hermetically seal. Although ferrofluid rotary seals for sealing vacuum and gases are part of a well established industry, the sealing of liquids has not been implemented yet. Literature learns...

A compact low-cost XY360° stage: using Arduino and PWM based amplifiers

The application of actively controlled micrometer precision positioning stages in products that are accessible to start-ups, individual consumers or third world countries is currently limited by their price and size. To solve this problem, the use of low-cost and compact components in stages is investigated. Earlier research done in the MSD...

Microcapillary magnetorheometer

Magnetorheological fluids, (MR fluids) have been around since the 1940's. After their discovery many applications followed, such as the MR clutch and MR damper. In these applications the fluids are subjected to ultra high shear rates although no knowledge is available on what happens to the rheological properties under these conditions. In...

Designs for rotary shaft fluid seals in an aqueous environment using fer- rofluid

Seals are used throughout the technology spectrum to prevent products form leaving their container or preventing foreign products to enter. With the sealing of rotary parts like shafts the seal needs to not only provide sealing capabilities, but also simultaneously allow for the desired movement without too much friction or wear. This is often...

Validation of the in-plane friction behaviour of a ferrofluid bearing

The repeatability of precision positioning systems can be improved by reducing the effects of stick-slip in the system. Stick-slip effects introduce a spontaneous jerking motion when overcoming the static friction coefficient, creating accelerations that are hard to predict. Contactless bearing types, such as magnetic levitation or fluid...

Nanometer Precision Six Degrees of Freedom Planar Motion Stage with Ferrofluid Bearings

This MSc research project is a feasibility study to explore the possibilities of using ferrofluid bearings in high precision, low load applications. Ferrofluids are fluids containing suspended ferromagnetic particles, which are influenced by magnetic fields due to their ferromagnetic properties. In similarity to for example iron powder, a...

Planar Ferrofluid Bearings for Precision Stages

Background The general objective of this research is to investigate the use of ferrofluids in planar bearings for precision stages. Ferrofluids are suspensions of magnetic nanoparticles in a base fluid. When in a magnetic field, these particles are attracted and the fluid is pressurized. The induced pressure can be used to carry a load. This...

Rheology of a ferrofluid and magnetorheological fluid in a magnetic field

Through flow experiments, we determined the rheological properties of both a ferrofluid and a magnetorheological fluid. These rheological properties were affected by the presence of an external, variable, magnetic field. The rheology of the ferrofluid was almost unaffected by the magnetic field. The rheology of the MRF was strongly affected by...