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Electropolishing for Improved Fit, Function & Appearance of Metal Fasteners

How electropolishing removes microscopic surface defects to deliver superior corrosion resistance, precision, and finish that passivation alone cannot match.

30× More corrosion resistance
vs. passivation alone
±.0002" Controlled stock
removal tolerance
70+ Years of electropolishing
expertise
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Overview

Why Fastener Finishing Matters

Bolts, screws, and other metal fasteners are essential to the structural integrity of a wide array of components — from steel fabricated structures to the infrastructure of public utilities.

A fastener with a poor finish or one prone to corrosion can threaten the integrity and safety of far more than a single bolt or screw. That is why the choice of finishing methods for metal fasteners is critical.

For fasteners where failure is not an option, electropolishing stands out. It removes a microscopically precise amount of surface material, eliminating discoloration, contaminants, and defects left behind by forging and machining — including microburrs, microcracks, and scratches. The result is a shiny, ultrasmooth, defect-free surface with enhanced corrosion resistance and decreased risk of part failure.

Key Benefits at a Glance

  • ✓Corrosion Resistance — 30× more effective than passivation alone
  • ✓Precision — Controlled stock removal to ±.0002"
  • ✓Galling Eliminated — Deburrs threads, prevents seizure of mating parts
  • ✓High Shine — Removes heat-treat discoloration for a premium finish
  • ✓Multi-Alloy Compatible — Stainless, titanium, aluminum, brass, copper, carbon steel & more
  • ✓Superior to Passivation — Removes surface material; passivation does not
The Science

How Does Electropolishing Work?

Often called a “reverse plating process,” electropolishing combines a modified electrical current with a chemical bath to dissolve a precise, even layer of surface material — leaving parts with 30× more corrosion resistance than passivation alone.

How Electropolishing Works — diagram showing power source, cathode, polishing solution and parts rack
  • 01

    AC to DC Power Conversion

    A power source converts AC current to DC at low voltages, providing the controlled electrical charge needed for the electrochemical process.

  • 02

    Cathode Plates Installed

    Copper or stainless-steel cathode plates are lowered into the chemical bath and connected to the negative side of the power source.

  • 03

    Parts Mounted to Rack

    Parts are fixed to a custom rack of titanium, copper, or bronze — connected to the positive side and immersed in the chemical bath.

  • 04

    Electrical Current Applied

    Current is applied, dissolving a precise, even layer of surface material — removing microburrs, microcracks, and contaminants at the molecular level.

30×
More Corrosion Resistance Electropolishing is a measurably superior result for fasteners in demanding environments
Compare Methods
Key Benefits

The Advantages of Electropolishing for Fasteners

From corrosion resistance to elimination of galling, electropolishing delivers results passivation alone cannot achieve.

Electropolishing Corrosion Resistance

Corrosion Resistance

Removes microburrs, microcracks, and contamination that become corrosion initiation sites. Improves the chrome-to-iron ratio on the surface. Particularly valuable for marine and underground applications.

Electropolishing Precision

Precision

Leaves parts ultrasmooth and defect-free with microscopically controlled stock removal. Ideal for threaded surfaces where tiny defects lead to problems with fit and function.

Electropolishing Corrosion Resistance

Galling Elimination

Eliminates galling by deburring threads and maintaining an ultraclean, corrosion-resistant metal surface — preventing the adhesion that causes mating parts to seize.

Electropolishing High Shine

High Shine

Removes staining and discoloration from heat treating or forging, leaving parts gleaming — a dramatic upgrade from the dull finish left by passivation.

Before & After

Birmingham Fasteners Before and After

Regardless of fastener size or function, electropolishing removes discoloration and defects for a safer and more durable part.

Before-and-after comparison of Birmingham Fastener hex head bolt and T-head bolt after electropolishing
Comparison

Electropolishing vs. Passivation for Fasteners

Both processes treat stainless steel and other alloys — but they are not equal across the attributes that matter most.

Electropolishing

  • ✓Removes a precise, even layer of surface material to ±.0002"
  • ✓Eliminates microburrs, microcracks, and defects passivation cannot touch
  • ✓Improves chrome-to-iron ratio — 30× the corrosion resistance of passivation
  • ✓Creates a high-shine finish — removes discoloration from forging and heat treating
  • ✓Eliminates galling by deburring threads, maintaining a corrosion-resistant surface
  • ✓Works on titanium, aluminum, brass, copper, carbon steel, and specialty alloys

Passivation

  • –Cleans with nitric acid — no stock removal; cannot address surface-level defects
  • –Useful for removing free iron and surface contaminants only
  • –Less effective at imparting corrosion resistance or enhanced durability
  • –Leaves parts with a dull finish — discoloration from forging or heat treating remains
  • –Does not address galling or thread-level surface defects
  • –Primarily suited to stainless steel; limited versatility across alloy types
Compatible Materials

Metal Alloys

Fasteners come in a large variety of materials that don’t always react well to passivation. Electropolishing works across a broad range of metal alloys:

Stainless 200–300
Stainless 400
PH Grade SS
Unusual SS Alloys
Nitinol
Titanium
Aluminum
Brass
Carbon Steels
Copper
Nickel
Specialty Alloys
Processing Methods

Bulk vs. Rack

The method of holding parts during processing affects precision and consistency. Able creates custom racking for each application.

Rack: Recommended

Parts evenly spaced on a custom rack ensure consistent electrical contact and chemical flow. Stock removal controlled to ±.0002".

Bulk Electropolishing

An economical option for fasteners, springs, and small cylindrical parts. Best suited for 300 and 400 series stainless steel.

Case Study

Birmingham Fastener

“We used to use passivation, but it was just a dull finish that didn’t look very good. I don’t know who found Able for us to try the electropolishing route, but it’s a night and day difference.” — Brad Porter, Quality Manager, Birmingham Fastener

Birmingham Fastener has worked with Able for nearly a decade finishing bolts, screws and fasteners for structural steel fabrication, transportation, water works, utilities, and OEMs.

Due to manufacturing techniques combining forging and shot blasting, metal fasteners can be left with discoloration and surface defects that impact durability and corrosion resistance. Electropolishing smooths fasteners for improved corrosion resistance — a critical advantage for water works customers.

Porter’s trust in Able’s quality allows the company to skip shipping parts back for review, now shipping directly from Able to end customers.

Materials304 and 316 stainless steel — rods, T-head bolts, oval-neck, and square-neck track bolts
Part Sizes⅜" up to 4" in diameter
ChallengeForging and shot blasting left parts with discoloration and surface defects impacting durability and corrosion resistance
ResultSuperior corrosion resistance for water works customers — quality consistent enough for direct-ship from Able to end customers without review
ProcessAutomated processing email notifications rated best-in-class among all vendors
IndustriesStructural steel fabrication, transportation, water works & utilities, OEM
Birmingham Fastener examples including polished and corroded bolts
Image courtesy of Birmingham Fastener.
1954Year Founded
150+Employees
14Robots Operating 24/5
30×Corrosion Resistance vs. Passivation
About Able Electropolishing

World’s Largest Electropolishing Specialist

Founded in 1954, Able is the world’s largest electropolishing specialist, with over 220 employees and 15 robots working 24 hours, five days a week in our state-of-the-art Chicago facility.

Able’s processes have been honed in collaboration with engineers in industries with no room for error — including aerospace, medical device, and national laboratories. Our Finish First methodology puts expertise to work in the prototyping stage, eliminating design flaws before they affect the finishing process.

Certified Standards

ASTM B912 ASTM A380 ASTM A967 AMS 2700 ISO 9001 ISO 13485 AS9100

Electropolishing 101 Webinar

Schedule a personal electropolishing webinar with you and your team to learn how electropolishing precisely removes microscopic imperfections and increase the form, fit and function of your critical metal parts.

  • Microsoft Teams screenshare with video chat
  • One-on-one with an electropolishing expert
  • Learn how electropolishing can be used on your parts
  • Send your NDA for review and signatures prior
Schedule Your Webinar

Ready to Improve Your Metal Fasteners?

Contact our team to discuss your application, material, and precision requirements. Free samples processed in 24–48 hours on production equipment.

Request a Quote Request a Free Sample Schedule a Webinar

Learn About the Electropolishing Difference


Electropolishing 101 Webinar

Electropolishing 101
Webinar

Learn everything you need to know about electropolishing as part of a private, interactive webinar. Let us know your availability and your part issues and our electropolishing experts can get you on our schedule.

Schedule Your Private Webinar
Try Electropolishing for Free: Sample Request

Try Electropolishing for Free:
Sample Request

Send us your parts and we’ll electropolish them for free – we’ll even pay for the shipping! Samples are processed and returned in a few days.

Request a Sample

Medical Device Manufacturing

Medical Device Manufacturing

From implantable devices to surgical instruments, electropolishing is a single-process treatment that results in biocompatible, safe and ultra clean parts.

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Aerospace

Aerospace

We offer aerospace vendors and OEMs our signature metal finishing services to increase fatigue-resistance for their metal parts, rendering them capable of withstanding the stress and corrosion that comes with long-term use.

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Pharmaceutical

Pharmaceutical

Our strict adherence to industry standards ensures that pharmaceutical components are electropolished in accordance with ASTM B912 and ASME BPE specifications.

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Automotive

Automotive

Corrosion resistance and microfinish improvement are essential for critical automotive parts, making electropolishing an increasingly beneficial option for automakers.

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Consumer Appliance

Consumer Appliance

Our metal finishing services help increase corrosion resistance for these parts, and by removing the outermost layer of metal with electropolishing the durability and longevity of these appliance components is increased.

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Food & Beverage

Food & Beverage

Electropolishing eliminates the buildup of bacterial biofilms and keeps equipment free of contaminants. Electropolishing delivers the level of sanitation required by a number of regulatory agencies.

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Hydraulics & Pneumatics

Hydraulics & Pneumatics

From robotics to mobile equipment, the uses of electropolishing in the hydraulics and pneumatics industry are many. Electropolishing reduces downtime and increases the life cycle of these components.

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Electronics

Electronics

Improving conductivity and performance is just one benefit electropolishing offers for electronics parts. The surface finish is improved by as much as 50%, removing imperfections from the material.

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Electropolishing, Passivation and Metal Surface Analytics Blog

Why Manufacturers Use Electropolishing for Precision Metal Parts

Electropolishing is a precise and controllable process for eliminating defects from the surface of metal parts. But it’s not the only finishing process available to manufacturers; there are mechanical, chemical and plating processes that can remove defects and improve the…

Read More

High-Quality Electropolishing for Small and Intricate Parts

Metal fabrication for parts used in the medical and electronics industries can involve dimensions as small as a grain of rice — or even a strand of hair. At that scale, surface defects may be invisible to the naked eye,…

Read More

When is Stainless Steel Passivation Required?

While stainless steel is known for its corrosion resistance, it contains iron, which is susceptible to corrosion, especially if parts are frequently exposed to moisture or harsh environments. Contamination left behind by machining processes can also impede the corrosion resistance…

Read More

Electropolishing Specialist vs. a Local Metal Finishing Company

Electropolishing is a highly controlled electrochemical process that directly impacts surface integrity, corrosion resistance, cleanliness, and performance.

Read More

Frequently Asked Questions

What services does Able Electropolishing provide?

We provide electropolishing, nitric & citric passivation, and vacuum vapor degreasing.

What are the maximum part sizes that can be processed for electropolishing, passivation, and vapor degreasing?

Electropolishing:

  • 300 & 400 series stainless steel: 108” Length x 41” Width x 42” Height
  • Copper, brass, aluminum, steel, and nickel alloys: 72” Length x 14” Width x 17” Height (best results are achieved on parts that are no larger than 12” square)
  • Titanium, Nitinol, tungsten, and niobium, etc. (refractory metals): 26” Length x 8-3/4” Width x 9-3/4” Height

Passivation:

  • Standard nitric acid passivation: 72” Length x 30” Width x 30” Height
  • Nitric acid/sodium dichromate: 20” Length, 20” Width x 20” Height
  • Citric acid: 26” Length x 18” Width x 15” Height

Vapor degrease:

  • Vapor degrease (vacuum): 23” Length x 16” Width x 10” Height

Note: If there is a question regarding our capabilities, please email a print for review to sales@ableelectropolishing.com.

What information do you require in order to receive a quotation?

We need a copy of the drawing, service needed, lot and annual quantities, process specification and packaging requirements.

What is your standard lead-time?

Standard delivery is 3 to 5 working days after receipt of order. Next day and same day services are offered at an additional cost. Please contact our sales department for further details.

What is the difference between passivation and electropolishing?

Passivation is a chemical process designed to remove free iron and other contaminants from the part surface. Electropolishing is an electro-chemical process that removes surface metal which improves micro finish, provides deburring and adds to the aesthetics of your part.