| Electro Polishing streamlines
the microscopic surface of a metal object by removing metal
from the object’s surface through an electrochemical
process similar to, but the reverse of, electroplating.
In Stainless Steel Electro Polishing, the metal is removed ion by ion from
the surface of the metal object. Electrochemistry and the
fundamental principles of electrolysis replace mechanical
finishing techniques as the final finish. In basic terms,
the object to be Electro-Polished is immersed in an electrolyte
and subjected to a direct electrical current. The object is
maintained anodic, with the cathodic connection being made
to a nearby metal conductor.
Smoothness of the metal surface is a primary and very advantageous
effect of Electro Polishing. A film of varying thickness
covers the surface of metal. This film is thickest over
micro depressions and thinnest over micro projections. Stainless Steel Electro Polishing
selectively removes microscopic high points “peaks”
much faster than the corresponding rate of attack on the
corresponding micro depressions or “valleys.”
Stock is removed as metallic salt. Metal removed under certain
circumstances is controllable and can be held to .0001 to
.0025 inch.
Metals that produce excellent results are: 200 &
300 Series Stainless Steel
ELECTRO POLISHING BENEFITS OF STAINLESS STEEL
- Improved Physical Appearance--No fine directional lines
from abrasive polishing, Excellent light reflection and
depth clarity, Bright, smooth polish; uniform luster of
shaped parts
- Enhanced Mechanical Properties—Less friction and
surface drag, Increase production and duty cycles in process
equipment and decrease fouling, plugging, scaling, and
product build-up, fatigue strength is not reduced, surfaces
is stress relieved, reduces galling of threads on stainless,
carbon steel and other alloys.
PHYSICAL CHARACTERISTICS OF ELECTRO-POLISHED SURFACE
- Smoothing without mechanical treatments provides
a correct and reproduces micro hardness measurement
on the surface of metals.
- Electro Polishing 0.001" of metal off the surface
will reduce the RMS value by approximately 1/2.
- Electro Polishing reduces friction, abrasion, and
increases magnetism.
- Electro Polishing is comparable in effect to stress
relieving anneal.
- No Hydrogen embrittlement develops because the work
is bathed in oxygen.
- Electro Polishing is used to remove grit lines thereby
producing a brighter and smoother finish.
- Best commercial method of Stainless Steel passivation.
- Aluminum, stainless steel, and bronze are shown to
have a higher resistance to aqueous corrosion than mechanically
polished specimens.
a. Reduced Stress
b. No contamination embedded in surface (Beilby layer)
c. Reduces surface area- is more uniform and chemically
homogeneous
d. Imparts a monomolecular oxide film on the surface
e. Part absorbs oxygen rather than hydrogen
f. Removes elemental iron from the surface of the metal
while increasing chromium concentration on surface and
nickel just beneath.
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