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Metal Finishing: Operations
Table of Contents
Background and Overview
Reasons for Change
P2 Opportunities
Where To Go for P2 Help
Complete List of Links

Essential Links:

Environmental Management Systems: A Guide for Metal Finishers
A comprehensive guide to implementing an EMS developed specifically for metal finishers of all sizes...

Environmental Protection Agency Sector Notebook: Fabricated Metal Products Notebook
Comprehensive environmental profile of the industry, TRI data, P2 opportunities, regulatory issues, ...

Guides to Pollution Prevention: The Metal Finishing Industry (EPA/625/R-92/011)
Overview of major metal finishing operations that generate waste, and opportunities in source reduc...

Metal Finishing Industry - Guide
Overview of common metal finishing techniques, and in-depth discussions of P2 practices and alternat...

This section provides information about the key processes and operations within the metal finishing industry, including inputs and waste streams.

Surface Preparation and Parts Cleaning

Surface preparation, cleanliness, and proper chemical conditions are essential to ensuring that finishes perform properly. Without a properly cleaned surface, even the most expensive coatings will fail to adhere or prevent corrosion. Surface preparation techniques range from simple abrasive blasting to acid washes to complex, multi-stage chemical cleaning processes.


Plating activities involve applying predominantly inorganic coatings onto surfaces to provide corrosion resistance, hardness, wear resistance, anti-frictional characteristics, electrical or thermal conductivity, or decoration. The process typically uses an electrical (cathode/anode) relationship between the workpiece and the plating bath. The most common forms of plating are:


Anodizing is an electrolytic process which converts the metal surface to an insoluble oxide coating. Anodized coatings provide corrosion protection, decorative surfaces, a base for painting and other coating processes, and special electrical and mechanical properties. Aluminum is the most frequently anodized material. Common aluminum anodizing processes include: chromic acid anodizing, sulfuric acid anodizing, and boric-sulfuric anodizing.

After anodizing, parts are typically rinsed, then proceed through a sealing operation that improves the corrosion resistance of the coating. Common sealants include: chromic acid, nickel acetate, nickel-cobalt acetate, and hot water.

Chemical Conversion Coating

Mechanical Finishing

Painting and Coating

Spray painting is a process by which paint is placed into a pressurized cup or pot and is atomized into a spray pattern when it is released from the vessel and forced through an orifice. Both liquid and powder coatings are sprayed onto the surface and cured. The newest line of coatings include ultraviolet curable powders and liquids.

Physical vapor deposition (PVD) coatings are typically thin coatings between 2 and 5 microns. PVD encompasses several deposition processes in which atoms are removed by physical means from a source and deposited on a substrate. Thermal energy and ion bombardment methods convert the source material into a vapor.


Etching produces specific designs or surface appearances on parts by controlled dissolution with chemical reagents or etchants.


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Hub Last Updated: 6/4/2013