Mechanical Polishing & Stainless Steel Polishing
See Photos of Mechanical Polishing
polishing covers grinding, polishing and buffing - all processes for improving the
surface conditions of a product for decorative or functional purposes.
The various techniques are abrading operations although some plastic working
of the surfaces may occur, particularly during buffing.
The Mechanical Polishing Process
The process is to do grinding first, polishing second, and buffing third.
In general, grinding permits far more aggressive abrading action than
polishing. Likewise, polishing is a far more aggressive abrading action
In grinding, polishing and buffing, labor is a major variable in the
process. The requirement if for highly skilled labor with years of experience
and a thorough knowledge of the art of their craft.
The basic mill plate and sheet metal finishes for stainless steel include
five grades that have finishes that are produced mechanically by using
abrasive compositions and buffing wheels. There is also available on the
market what is generically known as 'non-directional No. 8."
Special mechanical polishing procedures are required for preparing metal
surfaces, such as stainless steel, for electropolishing. Please look at the comparison table and
compare the various polished mill finishes against, the abrasive grit
number used to produce them, and the surface roughness readings before
and after electropolishing.
Polishing Mills Comparison Table
Surface Roughness, Ra
Surface Roughness, Ra
|* Values are Approximate. Electropolishing generally
reduces surface roughness readings of a non-electropolished
surface by 50 percent.
Basic Mill Plate Finishes for
Mechanical Stainless Steel Polishing
Polishing is an intermediate step used to improve the surface finish
from the grinding step, such as found on a common household stainless
steel sink - lustrous, but not mirror-like. Polishing uses abrasives firmly
attached to a flexible backing, such as a wheel, belt or orbital motion
Mechanical stainless steel polishing is an abrading operation used to remove or smooth
grinding lines, scratches, pits, mold marks, parting lines, tool marks,
stretcher strains, and surface defects that adversely affect the appearance
or function of the part. The process causes some plastic working of the
surface as metal is removed. A mechanically polished surface yields an
abundance of scratches, strains, metal debris and embedded abrasives,
and always distorts the metal surface. Burnishing metal by lapping or
buffing decreases the micro-inch roughness and improves the image-defining
quality of a surface, but it never completely removes the debris and damage
metal caused by mechanical polishing. Delstar's stainless steel mechanical polishing process is available on all grades of stainless including 316 and 304.
Learn more about the differences between the electropolishing process and the mechanical polishing process.
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