Industrial metal finishingis a process that is intended to lend a decorative veneer to a metal surface and to protect it from rust or corrosion. These finishing processes can also give the metal properties that make it more conducive to adhesion, solderability, hardness, wear resistance, and so on. Conversely, an unfinished metal surface is referred to as a mill finish.
Metal Finishing Types
There are several different types of metal finishing for use on different types of metals, for use in different applications, and to protect against specific types of corrosion. These include, but are not limited to;
- Metal Plating: A chemical bath is used to alter or coat a surface with a thin layer of metal
- Brushed Metal: Removes a thin surface layer of imperfections for a grained, smooth appearance
- Buff Polishing: Used for rounding edges and smoothing rough spots
- Metal Grinding: A more aggressive, abrasive process to smooth metal surfaces
- Metal Vibratory Finishing: Materials are placed in a drum with a substrate and abrasive pellets and are vibrated to forcefully remove sharp edges
- Sand Blasting: Accelerates sand, metal pellets, steel shot, or a number of other abrasives over the surface to smooth and clean metal
- Powder Coating: A decorative finish that is smooth, has an appearance similar to paint and can be textured, matte, or glossy
- Hot Blackening: A thin layer of black oxide is spread over a metal surface for a protective flat black finish
Types of Corrosion Protection
Industrial metal finishing can be employed to protect metals in one of two ways; sacrificial and protective (or barrier).
Barrier coatings protect metals from corrosion by acting as a shield from mechanical, thermal, or chemical damage. It can be most easily understood as a shield that stands between the metal to be protected and external forces or elements. Barriers typically contain some plastic resin which makes it easier to apply evenly and gives it much of its adhesive properties. Some incorporate additional layers of filler which provide a range of functionalities that are useful for different applications.
In sacrificial coating, a thin layer of the metal to be protected is damaged either chemically or mechanically. This is done to either provide simple beautification, or to create a layer that is not amenable to corrosive elements. The ‘bluing’ of the frames of firearms is a good example.
Other Uses for Industrial Metal Finishing
In a limited number of instances, some of these methods and techniques can be used to restore metal surfaces or components to an approximation of their original shape, or dimensions. This is done in cases where such dimensional restoration can effectively serve as a means of salvaging the item.
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