. The grinding speed can be significantly higher (~3000 rpm) compared to a few hundred rpm in conventional polishing or lapping (Zhang).
This technology allows removal rates to be increased by more than 100 times yet does not cause brittle fracture damage the way conventional polishing or lapping does (Zhang). The process achieves a high accuracy of 0.1 ¦m sphericity (Zhang).
This type of grinding works on the principle of the ômagneto-hydrodynamic behavior of a magnetic fluid that can float nonmagnetic materials suspended in it under the action of a magnetic fieldö (Zhang). The magnetic field is generated by a bank of permanent magnets having the N and S poles arranged alternately at the bottom of a magnetic fluid container (Zhang). To reduce consumption of the magnetic fluid, it is sealed within a chamber (Zhang). The future of Magnetic Fluid Supported Grinding may lead to its use in grinding brittle materials other than ceramic balls, such as in the planarization of wafer and lens grinding (Zhang).
Another innovation is externally-assisted grinding processes. These are grinding processes that are enhanced by electrical energy, dynamic motion, chemical activity, or thermal input; they also often overlap with externally assisted dressing techniques to keep the grinding wheel sharp and clean from loading (Webster 1). Several of the electrical externally-assisted grinding or truing/dressing systems developed in the last decade include:
Electro-Chemical Discharge Machining (ECDM)
Contact Discharge Truing and Dressing (CDTD)
Electro-Contact Discharge Dressing (ECDD)
Electro-Discharge Machining and Grinding (EDMG)
Electrochemical in-process Controlled Dressing (ECD)
Electro-Discharge Diamond Grinding (EDDG)
Rotary Electro-Discharge Machining by grinding wheel (REDM)
Abrasive Electro-Discharge Grinding (AEDG)
Electrolytic In-process Dressing (ELID) (Webster 1).
Although some of the above syst...