What is a Finishing Process?
Finishing processes refer to a variety of post-processing or post-manufacturing processes used to improve the appearance and fit of a metal product. Finishing processes are typically employed after initial shape forming procedures such as metal cutting, stamping, laser cutting, or welding. These processes can involve a variety of metal treatments such as polishing, cleaning, anodizing, plating, heat treating, passivating, tumbling, and shot peening to name a few.
The purpose of these processes is to improve the surface finish of a product by creating an aesthetically pleasing finish or to alter the product’s physical or chemical property profiles to match the desired end-use performance requirements. A wide range of metals are subject to a variety of finishing techniques depending on the desired visual and functional outcome.
Polishing and Cleaning
Polishing is a process by which the surface of a material is made to appear more aesthetically pleasing by making it smooth and mirror-like. Common techniques involve grinding a surface against a harder material to make it look smoother, shining a light against the surface to make it look brighter, using compressed air to blow away any dirt or dust on the surface, and using chemicals to remove any surface blemishes.
Another finishing technique is cleaning, which involves removing dirt and debris from the surface of the product to make it look more aesthetically pleasing. Common cleaning techniques include brushing, washing, degreasing, and wiping. Depending on the type of material and environmental conditions, some of these cleaning techniques may be able to remove dirt and debris from the surface while leaving the surface still in its initial condition or polished.
Anodizing, Plating, and Heat Treating
Anodizing is a process by which a layer of metal oxide is added to a metal’s surface. Anodizing provides a protective outer layer that helps to resist corrosion, wear, and abrasion. The anodizing process can be used to add a layer of color to the metal, to enhance electrical conductivity and welding properties, and even to add a degree of insulation.
Plating is a process by which a thin layer of metal is deposited onto a metal’s surface. This layer can be composed of one metal or a combination of multiple metals. Plating is often used to protect a metal from corrosion, add a coating for aesthetic purposes, or to add a layer of electrical insulation.
Heat treating is a post-manufacturing process that is used to change the internal structure of a metal to improve its physical and/or chemical properties. Depending on the process, heat treating can alter the metal’s strength, hardness, ductility, or other mechanical properties.
Passivating, Tumbling, and Shot Peening
Passivating is a type of metal finishing process that is used to increase the corrosion resistance of metal products. The passivating process typically involves exposing the metal product to an acid solution to form a thin oxide layer on the surface, which helps to protect the surface from corrosion. In some cases, it may also involve treating the metal with an alkaline solution as well as other agents to further enhance its corrosion resistance.
Tumbling is a finishing process used to remove any sharp edges from a metal product and produce a smoother surface finish. Tumbling is typically used after a metal product is laser cut and is processed in a tumbler to achieve the desired result.
Shot peening is a process by which small steel beads or shot are fired at a metal’s surface. This process improves the surface finish of the metal and increases its fatigue strength, which helps to reduce the chance of small cracks forming on the surface.
These are just a few of the many different types of finishing processes used in the metal working industry. Each offers unique benefits that can be leveraged by manufacturers depending on their application, desired outcome, and budget.
