Electropolish Your Mixing Impeller

Why consider electropolishing on agitator wetted parts?

Electropolishing employs electrical current and chemicals in a highly controlled electrolytic bath to create a smooth surface finish and produce a high luster finish. This stress-free process removes contaminants, passivates the surface, and creates an outer layer that retards corrosion. This all provides for a more sanitary mixing assembly.

Benefits Of Electropolishing For An Agitator And EP On the Mixing Impeller

• Electropolishing provides a smooth, clean, sanitary look to stainless impellers
• EP also passivates the mixing wetted parts
• EP removes elemental iron while increasing chromium concentration on the surface and nickel just beneath, a benefit for sanitary mixing impellers
• Provides a less reactive stainless agitator, better corrosion resistant mixer assembly
• Decreases contamination embedded in surface, allows for optimum sterilization and purity of the mixer and mixing impeller

Some photos of sanitary mixing impellers, some of them electropolished, can be found our sanitary impeller page.

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During the electropolishing process, the stainless mixer parts are immersed in an electrolytic chemical bath, which reaches both interior and exterior surfaces, and electrical current is applied at a controlled rate. The electropolishing process removes burrs, weld marks, and can produce a high-luster surface finish down to less than 10Ra, depending on the part configuration. This process is ideal for finishing mixer shafts, and mixing impellers . Electropolishing has become the standard for mixers used in the biotech and pharmaceutical industry, as well as aerospace equipment, food service equipment, medical and surgical devices, and semi-conductor parts.

Features of the Electropolishing Process:

Creates a clean, sanitary, uniform finish on the mixer and mixing impeller

Removes any tiny burrs and weld marks on agitator prop

Bright, highly reflective appearance which is ideal for sanitary mixers

Superior to passivation

Surface resistance to the impregnation of bacteria, important for sanitary mix applications

Chemically-bonded oxide layer resists corrosion for many years

Improved sterilization by removing surface impurities

What does electropoloshing do to the mixer wetted parts?

EP removes elemental Iron from the surface of stainless steel alloys, enhancing the chromium/nickel content resulting in dramatically improved resistance to corrosion. Electropolishing improves the near surface chemistry of stainless steel. Not only does it remove embedded particles and inclusions, it also improves the atomic ratios of the materials alloying elements. Electropolishing preferentially dissolves Iron from the material and leaves the surface with a higher relative concentration of Chromium. Upon exposure to oxygen, this improved surface will form a thicker and more uniform oxide layer with enhanced corrosion resistance properties.

Electropolished stainless steels are better suited to resist the onset of pitting corrosion, crevice corrosion, stress corrosion cracking, and microbiologically influenced corrosion.
EP improves surface smoothness by leveling micro peaks and valleys resulting in easier sterilization and maintenance of clean surface on medical, food and beverage, and biopharm mixing equipment. Improved microfinishes can do more than improve the appearance of a part. Superior microfinishes can improve seals, lower friction, reduce real surface area, allow for easier sanitation and cleaning.

The roughness of a surface can be measured and quantified by a profilometer. A profilometer is an instrument that measures roughness by moving a diamond tipped stylus across a surface. A profilometer will produce a reading of the surface roughness in either micro-inches (μin) or micrometers (μm).

The improved microfinish produced by electropolishing reduces product adhesion and contamination buildup. Reduced adhesion can limit product build up and significantly lengthen duty cycles. When cleaning is necessary, cleaning operations can be completed in less time and with less effort.

Electropolishing facilitates sterilization and maintenance of hygienically clean surfaces. Furthermore, electropolishing reduces the appearance of rouging on the inside surfaces of distillation columns, storage vessels, and distribution systems for hot purified water and clean steam. The most striking benefit of electropolishing is the resulting lustrous surface. Electropolishing is a non-mechanical process. No tools come in contact with the piece so there is no risk of creating directional polishing lines. The material is treated electrochemically, leaving a microscopically smooth surface that is highly lustrous.

There are many reasons to consider passivation and/or electropolishing for your sanitary mixer and agitators.