By shumijia | 19 October 2021 | 0 Comments
Various surface treatment roles after CNC precision parts machining
To prevent corrosion or simply improve appearance, engineers often specify additional finishing processes for some or all of the outer surfaces of a metal part after it has been machined or manufactured.
In addition, some of these finishes provide enhanced mechanical or electrical properties that contribute to the overall functionality of the component.
1. Electroplating - This process forms a thin metal coating on the substrate. The plating process passes a positively charged current through a solution containing dissolved metal ions and a negatively charged current through the metal part to be plated. The common metals used for electroplating are cadmium, chromium, copper, gold, nickel, silver, tin and zinc. Almost all base metals that conduct electricity can be plated to improve their performance.
2. Electroplating - This treatment is similar to electroplating; however, it does not use electricity. A reducing agent replaces the electricity and is included in the plating solution.
3. Chemical Treatment - This method involves a process that produces a thin film of sulfides and oxides through a chemical reaction. Typical uses are metal coloring, corrosion protection and priming of painted surfaces. Black oxide is a very common surface treatment for steel parts, and "passivation" is used to remove free iron from the surface of stainless steel parts.
4.Anodizing - This type of surface treatment is usually used for light metals such as aluminum and titanium. These oxide films are formed by electrolysis, and because they are porous, they are often specified with stains and colorants to improve aesthetic appearance. Anodizing is a very common surface treatment that prevents corrosion of aluminum parts. If wear resistance is also required, engineers can specify a version of this method that forms a relatively thick, extremely hard ceramic coating on the surface of the part.
5. Hot Dipping - This process involves immersing the part in dissolved tin, lead, zinc, aluminum or solder to form a surface metal film. Hot dip galvanizing is the process of immersing steel into a vessel containing molten zinc. Used for corrosion resistance in extreme environments, this surface treatment is commonly used for guardrails on roads.
6. Vacuum plating - Vacuum vapor deposition, sputtering, ion plating, ion nitriding and ion implantation are some of the more common metal surface finishing processes that utilize a high vacuum as part of the plating process. Ionized metals, oxides and nitrides are produced in a controlled environment. The parts are transferred into a vacuum chamber and the metals are deposited very precisely on the substrate. Titanium nitride is a surface treatment that extends the life of high steel and carbide metal cutting tools.
7. Painting - Surface treatment painting is usually specified by the engineer to enhance the appearance and corrosion resistance of the part. Spray painting, electrostatic painting, dip painting, brush painting and powder coating painting methods are some of the most common techniques used to apply paint to the surface of a part. There are several types of paint formulations available to protect metal parts in a variety of physical environments. The automotive industry has automated the painting process for cars and trucks, utilizing thousands of robotic arms and producing extremely consistent results
8. Thermal spraying - This type of surface treatment involves accelerated melting or heating of the material, which is then collided and mechanically bonded to the target surface. The wire or powder material, usually metal or ceramic, is melted by injecting it into a flame, arc or plasma stream. This process is sometimes specified by engineers when increased friction is a desirable characteristic. It is also commonly used on larger structural objects to protect against high temperatures, such as thermal barrier coatings for exhaust gas heat management.
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