Polishing
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Polishing Fabio Jose Pinheiro Sousa Mechanical Engineering, University of Kaiserslautern FBK, Kaiserslautern, RheinlandPfalz, Germany
Synonyms Buffing; Smoothing
Definition Polishing is a finishing process in which fine loose granules, while dispersed in a fluid or paste, are rubbed against the workpiece using a soft counterpart in order to smooth the surface of the workpiece without changing its nominal mass, dimension, or shape.
Theory and Application Polishing process consists in exposing the surface of a solid workpiece to the action of a mixture of fluid (carrier) and fine granules pressed against a soft moving counterpart (the lap). To assure a uniform distribution of pressure and the desirable softness at the same time, the laps typically used for industrial polishing consist of a soft pad
adhered to a rigid plate onto which the normal load is applied. Common materials for the softer layer of the pad are pitch, leather, cloth, polyurethane, or other polymeric materials, whose hardness usually ranges from 10 to 50 Shore D. The applied load is usually small (dozens of KN/m2). This process and its main components are exemplified in Fig. 1. In the classical polishing process, the surface is smoothed to a mirror level, so that specular reflections can occur on opaque surfaces and be perceived as luster or gloss. In case of transparent materials, such as lenses, polishing minimizes the amount of incident light physically scattered by asperities and small defects of the surface. In both mentioned examples, the surface need not to be smoothed on atomic scales but only to a fraction of the wavelength of the incident light, depending on the incident angle (Komanduri et al. 1997). After polishing, the achievement of surfaces presenting roughness with arithmetic averages (Ra) of 20–200 nm is fairly common. By reducing the amount and severity of surface damages, polishing may also increase the performance of mechanical components. Historically, however, the process was originally conceived for the fabrication of optical elements as well as obtaining aesthetic effects. Since introduced in the industrial practice at the beginning of the nineteenth century, polishing had been remaining for about seven decades entirely dependent on the craftsmen’s skills. The
# CIRP 2017 The International Academy for Production Engineering et al. (eds.), CIRP Encyclopedia of Production Engineering, DOI 10.1007/978-3-642-35950-7_6434-5
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Polishing, Fig. 1 Components of the polishing process (After Evans et al. 2003)
modernization started with the mass production of low- and medium-quality optics using high-speed polishing processes, which accordingly required the improvement of the polishing machines and the development of new lap materials (Rupp 1971).
Mechanisms of Material Removal Motivated by the industrial advance, extensive efforts were directed toward the description of the smoothing process during polishing. As a result, several hypotheses addressing the mechanisms of material removal have been proposed. Such hypotheses were individ
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