Electropolishing

Our electropolishing process removes impurities, imperfections, and burrs from the surface of metal objects, replacing traditional mechanical polishing or buffing.

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precision controlled

The electropolishing process, also known as electrochemical polishing, dissolves surface imperfections down to the micron, leaving the surface clean and polished. We carefully formulate our electrolyte chemistries to ensure optimum results for stainless steel finishing.

electropolishing, polishing, corrosion resistance, passivation

Products Requiring Electropolishing

Medical implants and devices
Surgical instruments
Aerospace components
Precision electronic components
Light fittings
Cookware and utensils
Hydraulic fittings
Fasteners
Wire racks
Automotive parts

Results That Matter

Electropolishing removes subsurface contaminants that cause corrosion, providing an enhanced level of passivation (ASTM B912). This process offers these additional benefits.

Benefits of Electropolishing

Up to 30x corrosion resistance over passivation
No directional lines from abrasive polishing
Strips contaminants
Smooths surface imperfections
Uniform Luster
Meets tight tolerances
I.D. Polishing

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Surface Roughness Conversion Chart
Ra (micrometers)	Ra (microinches)	RMS	CLA (N)	Rt	N	Cut-off Length (in)	Cut-off Length (mm)
0.025	1	1.1	1	.3	1	0.003	0.08
0.05	2	2.2	2	0.5	2	0.01	0.25
.1	4	4.4	4	0.8	3	0.01	0.25
.2	8	8.8	8	1.2	4	0.01	0.25
0.4	1.6	17.6	16	2.0	5	0.01	0.25
0.8	32	32.5	32	4.0	6	0.03	0.8
1.6	63	64.3	53	8.0	7	0.03	0.8
3.2	125	137.5	125	13	8	0.1	2.5
6.3	250	275	250	25	9	0.1	2.5
12.5	500	550	500	50	10	0.1	2.5
25.0	1000	1100	1000	100	11	0.3	8.0
50.0	2000	2200	2000	200	12	0.3	8.0
Ra = Roughness Average in micrometers or microinches. RMS = Root Mean Square in microinches. CLA = Center Line Average in microinches. Rt = Roughness Total in microns N = New ISO (grade) scale numbers. Cut-off Length = Length required for sample.

FAQs

The reverse plating process often called “electropolishing” is also referred to as electrochemical polishing, anodic polishing, electrolytic polishing, or EP.

The electropolishing process involves an electrical current passing through stainless steel or alloy parts submerged in a sulfuric or phosphoric acid bath mixture to remove a thin metal surface layer.

Polishes areas inaccessible by other polishing methods
Improves surface reflectivity and brightness
Levels micro peaks and valleys for better sterilization (roughly 20-40 micrometers thick)
Removes surface iron and enhances the chromium/nickel content
Slightly reduces the part size, if necessary
Provides a corrosion-resistant surface
Removes surface discoloration from heat treating and/or oxidation

AC7000 – AUDIT CRITERIA FOR NADCAP ACCREDITATION

AC7108 REV I – NADCAP Audit Criteria for Chemical Processing

AC7108 Anodize; Hard Anodize and Sulfuric Anodize (Not for Metal Bond) – AC7108/8 must also be selected
AC7108 Chromate (non-hexavalent)
AC7108 Passivation
AC7108 Electropolish
AC7108 Standalone Cleaning
AC7108 Descaling
AC7108 Solution Analysis & Testing – AC7108/4 must also be selected
General Cleaning & Pre-Cleaning
Alkaline Cleaning
Chemical Cleaning
Titanium Cleaning
Emulsion Cleaning
Semi-Aqueous Cleaning
Solvent Cleaning
Ovens for Thermal Treatments – Heat Processing; Part Dying
Stripping of Coatings
Inorganic Coatings
Other Stripping

AC7108/4 REV C – NADCAP Audit Criteria for Solution Analysis and Testing in Support of Chemical Processing to AC7108

Solution Analysis (In Support of AC7108)
Testing Performed Internally (In Support of the Chemical Process Accreditation)
B05 – Salt Spray Testing (In Support of Chemical Process Accreditation)
B06 – Water Immersion / Humidity Testing (In Support of AC7108)
B09 – Taber Wear Testing (In Support of AC7108)
B10 – Adhesion Testing (In Support of AC7108)
B13 – Coating Weight Testing(In Support of AC7108)
B 14 – Conductivity Testing (In Support of AC7108)
B15 – Resistivity Testing (In Support of AC7108)
B16 – Coating Thickness Measurement (In Support of AC7108)
B23 – Other Testing (In Support of AC7108)

AC7108/8 – NADCAP Audit Criteria for Anodizing (Not for Metal Bond)

Anodized Aluminum, Hard Anodize
Anodize Aluminum, Sulfuric Acid
Dye
Seal

AC7108/11 – NADCAP Audit Criteria for Conversion Coating

Aluminum, Non-Hexavalent Chrome Alternatives

AC7108/12 REV A – NADCAP Audit Criteria for Standalone Cleaning, Descaling, Passivation, and Electropolishing

Passivation

Electropolishing reduces surface irregularities and micro-level peaks and valleys, leading to a smoother and more uniform surface with a lower RA value. Typically, RA values can be reduced by 10 to 30 microinches or more, depending on the material and initial surface condition.

Electropolishing is commonly used for stainless steel.

Electropolishing may not be suitable for components with intricate internal passages, as the process primarily affects external surfaces. It may also not be suitable for all metals and alloys, so a feasibility study is recommended.

To determine the expected RA improvement, you should consult with our electropolishing experts at Arrow. We can evaluate your part’s current condition and provide a more accurate estimate of the improvement achievable through electropolishing.

Electropolishing is effective for a wide range of Stainless-Steel metal components, but its suitability depends on factors such as the geometry, size, and material of the part. It’s best to consult with our electropolishing experts at Arrow for specific recommendations.

Electropolishing Specs
ASTM B912-02	1.1 This specification covers the passivation of stainless steel alloys in the 200 (UNS2XXXX), 300 (UNS3XXXX), and 400 (UNS4XXXX) series, and the precipitation-hardened alloys, using electropolishing procedures	6. Test Procedures 6.1 Water Immersion Test (Specification A967/A967M)— The article(s) shall be alternately immersed in distilled water for 1 h, then allowed to dry for 1 h for twelve wet-dry cycles (24 h total). Failure is indicated by the presence of red rust or staining as a result of the presence of free iron on the surface.	6.2 Humidity Test (Practice A380/A380M, Specification A967/A967M)—The article(s) shall be subjected to 100 % humidity at 38 6 2°C in a suitable humidity cabinet for a period of 24 h. Failure is indicated by the presence of red rust or staining as a result of the presence of free iron on the surface.	6.3 Salt Spray (Fog) Testing (Practice B117 (ISO 9227))— The article(s) shall be subjected to the prescribed test for a minimum of 2 h in an accredited cabinet. Failure is indicated by the presence of red rust or staining as a result of the presence of free iron on the surface.	6.4 Copper Sulfate Test (Practice A380/A380M, Specification A967/A967M)—See Appendix X2. The article is swabbed with an acidified solution of copper sulfate. Failure is indicated by the presence of a copper-colored deposit or copper-colored spots, or both. This test is not to be used on martensitic 400 series stainless steels.
ES2005 Rev A (Parker Hanifin Quick Coupler Division)	2.3 The Electropolish process in this spec shall be primarily used to improve appearance and corrosion resistance. 2.4 Unless otherwise specified on the drawing, the material removal shall be .0002" to .0004".	3.1 Parts to be electropolished shall be cleaned by any method that leaves the parts free of oil, grease, rust, scale or other foreign matter without adverserly affecting the base material. 3.2 Electrpolishing may be accomplished by any applicable process provided the finsed product meets the requirements of this spec. 3.3 An electropolished partshall have a smooth, high lustre, uniformly bright surface, free of surface contamination, residual solution and solution stain. 3.4 An electropolished part shall be capable of meeting the applicable quality assurance provision of QQ-P-35C (superceded by ASTM A967-17).	ASTM A967-17 Testing Methods we offer-13.3.1 Practice A—Water Immersion Test (see 14.1), 13.3.2 Practice B—High Humidity Test (see 14.2), 13.3.3 Practice C—Salt Spray Test (see 14.3), 13.3.4 Practice D—Copper Sulfate Test (see 14.4)