Surface finishing is a broad range of industrial processes that alter the surface of a manufactured item to achieve a certain property. Finishing processes may be employed to: improve product appearance, adhesion or wettability, solderability, corrosion resistance, tarnish resistance, the chemical resistance, the wear resistance,

hardness In materials science, hardness (antonym: softness) is a measure of the resistance to plastic deformation, such as an indentation (over an area) or a scratch (linear), induced mechanically either by Pressing (metalworking), pressing or abrasion ...

, modify

electrical conductivity Electrical resistivity (also called volume resistivity or specific electrical resistance) is a fundamental specific property of a material that measures its electrical resistance or how strongly it resists electric current. A low resistivity in ...

, remove burrs and other surface flaws, and control the surface

friction Friction is the force resisting the relative motion of solid surfaces, fluid layers, and material elements sliding against each other. Types of friction include dry, fluid, lubricated, skin, and internal -- an incomplete list. The study of t ...

.. In limited cases some of these techniques can be used to restore original dimensions to salvage or repair an item. An unfinished surface is often called '' mill finish''. These processes can improve the durability, performance and even the appearance of the surface being finished. Surface finishing is often one of the final steps taken when working metal and is essential for guaranteeing that metal components meet the requirements of the necessary finish. Surface finishing processes can be categorized by how they affect the workpiece: *Removing or reshaping finishing *Adding or altering finishing *Coating Methods *Chemical Treatments *Mechanical Treatments Mechanical processes may also be categorized together because of similarities in the final

surface finish Surface finish, also known as surface texture or surface topography, is the nature of a interface (matter), surface as defined by the three characteristics of lay, surface roughness, and waviness.. It comprises the small, local deviations of a ...

Adding and altering

* Blanching * Burnishing * Calendering * Case hardening * Ceramic glaze * Cladding *

Corona treatment Corona treatment (sometimes referred to as air plasma) is a surface modification technique that uses a low temperature corona discharge plasma to impart changes in the properties of a surface. The corona plasma is generated by the application ...

*Diffusion processes: ** Carburizing **

Nitriding Nitriding is a heat treating process that diffusion, diffuses nitrogen into the surface of a metal to create a case-hardening, case-hardened surface. These processes are most commonly used on low-alloy steels. They are also used on titanium, alum ...

* Electroless plating *

Electroplating Electroplating, also known as electrochemical deposition or electrodeposition, is a process for producing a metal coating on a solid substrate through the redox, reduction of cations of that metal by means of a direct current, direct electric cur ...

* Galvanizing * Gilding * Glazing * Knurling *

Paint Paint is a material or mixture that, when applied to a solid material and allowed to dry, adds a film-like layer. As art, this is used to create an image or images known as a painting. Paint can be made in many colors and types. Most paints are ...

ing * Passivation/ Conversion coating ** Anodizing ** Bluing ** Chromate conversion coating ** Phosphate conversion coating *** Parkerizing ** Plasma electrolytic oxidation * Peening ** Shot peening ** Laser peening * Pickling * Plasma spraying *

Powder coating Powder coating is a type of coating that is applied as a free-flowing, dry powder. Unlike conventional liquid paint, which is delivered via an evaporating solvent, powder coating is typically applied electrostatically and then Powder coating#Curin ...

* Thin-film deposition **

Chemical vapor deposition Chemical vapor deposition (CVD) is a vacuum deposition method used to produce high-quality, and high-performance, solid materials. The process is often used in the semiconductor industry to produce thin films. In typical CVD, the wafer (electro ...

(CVD) **

** Electrophoretic deposition (EPD) ** Mechanical plating ** Sputter deposition **

Physical vapor deposition Physical vapor deposition (PVD), sometimes called physical vapor transport (PVT), describes a variety of vacuum deposition methods which can be used to produce thin films and coatings on substrates including metals, ceramics, glass, and polym ...

(PVD) ** Vacuum plating *

Vitreous enamel Vitreous enamel, also called porcelain enamel, is a material made by melting, fusing powdered glass to a substrate by firing, usually between . The powder melts, flows, and then hardens to a smooth, durable vitrification, vitreous coating. The wo ...

Removing and reshaping

Abrasive blasting Sandblasting, sometimes known as abrasive blasting, is the operation of forcibly propelling a stream of abrasive material against a surface under high pressure to smooth a rough surface, roughen a smooth surface, shape a surface or remove sur ...

** Sandblasting * Burnishing * Chemical-mechanical planarization (CMP) *

Electropolishing Electropolishing principle: 1. Electrolyte 2. Cathode 3. Workpiece to polish (Anode) 4. Particle moving from the work-piece to the cathode 5. Surface before polishing 6. Surface after polishing Electropolishing, also known as electrochemical poli ...

* Electrochemical machining * Flame polishing * Gas cluster ion beam * Grinding * Industrial etching * Laser ablation * Laser engraving * Linishing * Magnetic field-assisted finishing * Mass finishing processes ** Tumble finishing ** Vibratory finishing * Peening ** Shot peening ** Laser peening * Pickling *

Polishing Polishing is the process of creating a smooth and shiny surface by rubbing it or by applying a chemical treatment, leaving a clean surface with a significant specular reflection (still limited by the index of refraction of the material accordi ...

** Buffing ** Lapping * Superfinishing

Mechanical finishing

Mechanical finishing processes include:. *

* Burnishing * Grinding ** Honing * Mass finishing ** Tumble finishing ** Vibratory finishing *

** Buffing ** Lapping The use of abrasives in metal polishing results in what is considered a "mechanical finish".

Metal finish designations

; #1 Finish Annealed and descaled after hot rolling, this finish is suitable for industrial applications requiring heat resistance and corrosion resistance, where smoothness of finish is unimportant, such as chemical tanks, aircraft heaters, steam turbine shrouds and piping. ; #3 Finish Also known as grinding, roughing or rough grinding. These finishes are coarse in nature and usually are a preliminary finish applied before manufacturing. An example would be grinding gates off of castings, deburring or removing excess weld material. It is coarse in appearance and applied by using 36–100 grit abrasive. When the finish is specified as #3, the material is polished to a uniform 60–80 grit. ; #4 Architectural finish Also known as brushed, directional or satin finish. A #4 architectural finish is characterized by fine polishing grit lines that are uniform and directional in appearance. It is produced by polishing the metal with a 120–180 grit belt or wheel finish and then softened with an 80–120 grit greaseless compound or a medium non-woven abrasive belt or pad. ; #4 Dairy or sanitary finish This finish is commonly used for the medical and food industry and almost exclusively used on stainless steel. This finish is much finer than a #4 architectural finish. This finish enhances the physical appearance of the metal as well as increases the sanitary benefits. One takes great care to remove any surface defects in the metal, like pits, that could allow bacteria to grow. A #4 dairy or sanitary finish is produced by polishing with a 180–240 grit belt or wheel finish softened with 120–240 grit greaseless compound or a fine non-woven abrasive belt or pad. ; #6 Finish Also known as a fine satin finish. This finish is produced by polishing with a 220–280 grit belt or wheel softened with a 220–230 grit greaseless compound or very fine non-woven abrasive belt or pad. Polishing lines will be soft and less reflective than a #4 architectural finish. ; #7 Finish A #7 finish is produced by polishing with a 280–320 grit belt or wheel and sisal buffing with a cut and color compound. This is a semi-bright finish that will still have some polishing lines, but they will be very dull. Carbon steel and iron are commonly polished to a #7 finish before chrome plating. A #7 finish can be made bright by color buffing with coloring compound and a cotton buff. This is commonly applied to keep polishing costs down when a part needs to be shiny but not flawless. ; #8 Finish Also known as a mirror finish. This finish is produced by polishing with at least a 320-grit belt or wheel finish. Care will be taken in making sure all surface defects are removed. The part is sisal buffed and then color buffed to achieve a mirror finish. The quality of this finish is dependent on the quality of the metal being polished. Some alloys of steel and aluminum cannot be brought to a mirror finish. Castings that have slag or pits will also be difficult, if not impossible, to polish to a #8. A polished PVD finish can achieve a similar appearance due to the smooth, reflective nature of the coating process.

References

Notes

Bibliography

*. {{DEFAULTSORT:Surface Finishing Grinding and lapping ca:Acabat