Many types of machining process have been developed and utilized by researchers and engineers with objectives to improve devices’ performance, function, economic, compact, light-weight, and design.
Loose abrasive machining is one of the processes, which contributes to improving precision, such as surface roughness and form accuracy of manufactured components.
Loose abrasive process is categorized as a constant pressure process. Since abrasive is not fixed, material removal depends on the amount of pressure that is set. On the other hand, fixed abrasive process such as grinding is categorized as a constant depth-of-cut process. The amount of material removal will therefore depend on how much the depth of cut is set.
Preston’s equation is a well-known formula in explaining the relationship between material removal rate (MRR) during process relative to main parameters (Preston 1927). This is useful in the understanding of material removal mechanism under constant pressure process. According to Preston’s equation, the MRR is proportional to the product of the polishing pressure, p, and relative velocity between workpiece and polishing tool, v:

where h is the amount of material removal; t is the processing time; and k is the Preston coefficient. Since this equation is adaptable to most of the loose abrasive processes, it is useful to aid in the understanding and estimation of the processed results.
In this chapter, processes for ultrasmooth surface, p complex geometry, and mass finishing are introduced respectively. Followed by a machining process, using ultrasonic is also introduced with detail information.