More You Should Know About Anodizing Aluminum for your CNC Machining Parts
Anodizing is one of the most common surface treatment options available for aluminum.We’ve probably all seen anodized pieces used in a variety of applications, ranging from some of Apple’s iPhones and iPods to sprockets on motorcycles and karts.The process is well-suited for aluminum parts made from a variety of different manufacturing processes, such as CNC machining, milling,turning, casting and stamping.
What is Anodizing?
Anodizing is a process that is used to promote the formation of an aluminum oxide layer on a base material more rapidly or with greater thickness than it normally would under natural conditions. While anodizing does work for several other base materials, aluminum responds the most effectively to anodizing. Anodizing first became popular in the 1920’s as a means to prevent the corrosion of aluminum components. Since then, it has been used not only for corrosion resistance, but also for wear resistance and dyeing aluminum. Since aluminum oxide is not nearly as conductive as aluminum, it can be also used for electrical insulation purposes. Anodizing has many benefits, but it is important to note that it will not increase the strength of the aluminum underneath the anodized surface.
What types of Anodizing?
With reference MIL-A-8625 throughout to correlate with an industry specification. In this specification, there are three types and two classes of anodizing. The three types are as follows:
Type I
Type I and IB – Chromic Acid Anodizing
Type IC – Non-Chromic Acid Anodizing as a replacement to type I and IB
Type II
Type II – Conventional coating from a sulfuric acid bath
Type IIB – Non-chromate alternative for type I and IB coatings
Type III
Type III – Hard Anodize
Each type of anodize is used for a specific reason. Some of those reasons are:
Type I, IB, and II are used for corrosion resistance and some degree of abrasion resistance. For applications that are fatigue critical, type I and IB are used because they are a thinner coating. One example of this is highly fatigued structural components on aircraft.
Type IC and IIB are used when a non-chromate alternative is desired for I and IB. This is often the result of environmental regulations or requirements. When developing systems in the defense industry, new contracts often required environmentally friendly options (type IC and IIB) because of the presence of hexavalent chromium in type I and IB. However, it is possible to get waivers where required by geometry complexities and extensive re-qualification efforts.
Type III is used primarily increased for abrasion and wear resistance. It’s a much thicker coating, so it will outperform the other types with respect to abrasion and wear. This coating may reduce fatigue life, however. Type III anodize is frequently used on firearm components, gears, valves, and many other components that will slide relative to each other.
All types may help the adhesion of paints and some other bonding agents compared with bare aluminum. In addition to the anodizing process, some parts may be dyed, sealed, or treated with other materials, such as dry film lubricant. If a part is to be dyed, it’s considered Class 2, whereas an undyed part is Class 1.
What is Anodizing Used For?
Anodizing is most commonly used for improved corrosion resistance on certain types of aluminum alloys. Aluminum alloys that are subject to marine environments typically benefit from anodizing. Ship hulls, dock components, and oil rig structures are common examples of these.
Anodizing is also used for abrasion control. Aluminum that has not been oxidized is a relatively soft material when compared with steel or titanium. Aluminum oxide, on the other hand, is an extremely hard material. In fact, aluminum oxide is often used in sandpapers because of its high hardness. When the anodizing process forms an aluminum oxide layer on the outside of an aluminum alloy, it greatly increases its wear resistance because aluminum oxide is such a hard material. Applications where anodizing is used for wear resistance include aluminum components that are subjected to constant movement and contact with other materials.
Dyeing is another popular application of anodized aluminum. The aluminum oxide layer that is created on an aluminum alloy during the anodizing process is porous. This allows some dyes to be absorbed by the oxide layer. Aluminum alloys that couldn’t be dyed before can now be made to be a variety of colors. Applications of dyeing anodized aluminum include artwork and and aluminum signs.
Worthy Hardware utilizes the latest in CNC technology to make high precision machined parts. We have a full line of 3, 4 and 5 axis machining centers equipped with automation to handle both small and large volume runs. Components are produced with standard tolerances of +/-0.005”. Tighter tolerances may be specified but may affect pricing and delivery.
Worthy Hardware is a CNC manufacturing and sheet metal fabrication company,including CNC machining services,CNC milling services, CNC turning services, laser cutting services and stamping services.Call us +86-76989919645 or email us [email protected] for more discounts for your projects.