University research in the Soviet Union, Bulgaria, Germany, Poland, and US began in the 1960s with practical usage appearing by the 1980s and 1990s.
The growth of the semiconductor, aerospace, and optics industries have resulted in the continued development of better methods for attaining high form accuracy and surface integrity.
Since MAF does not require direct contact with the tool, the particles can be introduced into areas which are hard to reach by conventional techniques.
The normal force at the surface applied by a magnetic particle can be defined as a function of area S and magnetic field B in the following expression:[3] The tangential force of the brush can be defined as a change in energy of the brush due to an obstruction.
however increasing particle size has adverse effects such as the inability to hold small abrasives and the presence of air gaps as a result of a larger packing factor.
Close control of the surface texture and roughness can be manipulated through the selection of the right abrasive size and oscillation speed and spindle rpm.
[2] MAF can be divided into three main categories, each defined by the type of magnetic particles utilized in the finishing operation.
Each type has its specific niche that it may fulfill better than its counterparts therefore knowing the application of the process is key to selecting the proper finishing operation.
The different MAF processes are listed in increasing surface roughness resolution while decreasing in applied force.
Unlike a conventional brush the magnetic chains of particles are flexible and will conform around any geometry.
Therefore, this specific variety of MAF is aimed towards finishing of the free form external surfaces such as airfoils or prosthesis.
The main difference between internal and external finishing operations is the location of the brush and the workpiece however the application of force is essentially the same hence the material removal mechanism is identical in both cases.
Magnetorheological finishing or "MRF" uses the shearing of a viscous mixture of micron sized iron particles, abrasives, and oil to impart a machining force or pressure onto the workpiece surface.
This flow results in material removal of the sidewalls through the momentum of the fluid and shearing of the side walls with the abrasives.