Electropolishing Services

What it is and when to specify it

Electropolishing is an electrochemical process that removes a very thin layer from the surface of a stainless steel part to produce a bright, smooth, low-friction finish. It is often described as the reverse of electroplating: instead of depositing metal, the process dissolves it in a controlled way. Because the metal is removed electrochemically rather than with abrasives, the finish has no directional grain and reaches into recesses, internal corners, and thread roots that a wheel or belt cannot easily touch.

That is the key difference from mechanical polishing, which grinds and buffs the surface with abrasives and always leaves some direction to the finish. Electropolishing levels the microscopic peaks of a machined surface instead, which is what gives it the bright appearance and the cleanability that matter most in hygienic applications.

Specify it when a stainless part needs a bright, easy-to-clean surface, when micro-burrs and sharp edges have to come off, or when corrosion resistance matters. We arrange electropolishing through our vetted partner network, managed under one quality process, and stay your single point of contact.

Specifications

The process is controlled by material removal rather than by an added coating, so the specification centres on how much metal comes off and how bright the result should be. A common trade range removes from a few micrometres up to several tens of micrometres; the exact allowance is confirmed per drawing, because it must be planned into machined dimensions before the part goes to finishing.

Surface roughness is the second variable. Electropolishing reduces roughness and leaves a mirror-like appearance, but the target value depends on the part. A decorative cover may only need a uniform bright surface, while a food-contact or fluid-handling part may call for a tighter finish. We confirm the target roughness per drawing rather than assuming a single number.

Edge and burr condition is the third. Because the process attacks high spots first, it reduces micro-burrs and rounds the sharpest corners, which improves handling and cleanability. ASTM B912 is the standard most drawings reference for this finish; we work to the callout on your drawing and confirm every variable before quoting.

Which materials and parts it suits

This finish is for stainless steel, and in practice the grades we finish most are 303, 304, 316 and 316L, with 301, 304L, 410, 416 and 17-4PH running the same line. 303 machines freely and takes a good finish for fittings and fasteners, 304 and 304L are the general-purpose grades for enclosures and brackets, 316 and 316L are chosen where the part faces moisture or chemical exposure, and 17-4PH is finished after hardening where the part needs both strength and a clean surface. They all come back bright and clean from the line.

The parts that benefit most are the ones where hygiene and cleanability drive the design. Food-contact hardware, medical components, and semiconductor-related parts are the classic cases, because a smooth, low-adhesion surface resists product build-up and is easy to clean. Stainless steel machined parts such as fittings, valve bodies, manifolds, and brackets also suit it well when they need a bright, corrosion-resistant surface.

Finishing is applied through our vetted partner network, managed under one quality process. We remain the single point of contact, so you do not need to screen finishers yourself, and every order ships with a material certificate and pre-shipment photos.

Corrosion, wear and dimensional impact

On corrosion, electropolishing does two useful things at once. It strips the free iron and inclusions left behind by machining, and it leaves a passive, chromium-rich surface that resists rust and staining. That is a real step up from a raw machined stainless surface, which is why the finish is common where parts stay wet or must stay clean.

On wear and friction, the smooth surface reduces microscopic peaks, so moving or sliding contact runs with less friction and fewer crevices where contamination can collect. It is not a hard coating and does not add thickness; it improves the surface rather than building one up.

The dimensional impact is the part to plan for. Because material is removed, bores, threads, and fits shift slightly, so the removal allowance has to be built into the drawing. This is the main difference from passivation, which cleans the surface with no meaningful metal removal, and from mechanical polishing, which uses abrasives. See the surface finishes overview to compare the options.