A mirror-like surface requires the total elimination of all surface roughness. The
is capable of achieving such finishes by selectively filtering out successive levels of roughness without changing the basic form of the surface.
The diagram below demonstrates how
categorizes the different levels of roughness.
to obtain mirror-like surfaces offers a number of advantages but also has some limitations.
maps a surface as a collection of different frequencies of roughness. It then removes only the targeted frequency ranges, moving from the highest frequencies to lower ones. As a result of this extremely precise approach,
achieves mirror-like surfaces with far less material removal than traditional cutting action polishing processes
Limiting the material removal to specific frequency ranges gives
other benefits that differentiate it from classic polishing processes. Since the frequencies of roughness
removes are significantly higher than the frequencies of the underlying form of the part, the resulting mirror-like finish leaves edges sharp and fine details undisturbed, meaning that
is very well suited to creating uniform mirror-like finishes on complex geometries.
is an isotropic (homogeneous) treatment, if obtaining a mirror-like surface requires removal of form errors (i.e. low frequency),
may not be a good solution. Defects in the form of the part will require localized removal of material, and probably a lot of material relative to the amounts
typically removes. In general, if a part requires non-homogeneous removal of material (i.e. changes to the actual shape of the part),
is not likely to be the best choice.
Mirror-like polishing is often required in luxury applications (watch-making, jewellery), medical implant and instrumentation applications, and plastic injection molding.
In the case of luxury goods, minimal removal of material is critical not only because the item needs to retain all of its subtle design details and sharp edges, but also because of the importance of preserving the maximum amount of the precious materials (i.e. gold, platinum) used to make the parts. To take advantage of
's minimal material removal, the initial surface should be free of shape defects. Typically a 320 grain grinding or a fine turning operation are appropriate prior to applying
. When these conditions are met,
can deliver a homogeneous mirror-like polish with far less material removal and greater retention of detail than can be attained using other polishing methods.
For medical and injection molding applications the emphasis is more focused on maintaining tolerances.
is the best path to a mirror-like finish for these applications because of its ability to preserve complex geometries while still delivering a uniformly polished surface.
's broad material and coatings compatibility is another benefit in these applications, and in many cases
also delivers shorter, more predictable lead times at lower cost.
also creates mirror-like finishes on MIM and/or CIM parts, provided the initial surface is free of porosity.
In conclusion, depending on the applications and markets, the mirror-like surface produced by
is often the best choice due to low material removal, the ability to preserve the initial shapes and designs, an improvement of technical properties of the surface, reproducibility and homogeneity, accessibility to complex shapes, and superior lead times and overall cost.
- © MicroTek Finishing 2012