No matter which type of industry you are working in, for example, automotive, architecture, etc., you would have heard about the anodizing process because the anodized tools and devices are used widely in the home furniture, marine industry, and parts of sports equipment. You would be familiar with the anodizing process if you love cycling. However, this process is mainly used in electronics and aerospace industries, where some of the parts need to be corrosion-free.
As many processes are going on in the industry, which can expose various metals used in those industries, the anodizing process can be applied. They are used for many different metals, ranging from aluminium to titanium.
Anodizing is considered one of the best ways to protect any given aluminium surface because aluminium is the most versatile metal amongst them. Thus, here we are going to discuss some of the key components that you need to know about anodizing aluminium, looking at the what, how, and why of aluminium anodization.
Let us first start with what is anodized aluminium.
What is anodized aluminium?
Anodizing is an electrochemical process where the metal is immersed in a series of tanks, wherein one of the tanks, the anodic layer, is grown from the metal itself. It also helps to converts the metal surface into a decorative, durable, corrosion-resistant, anodic oxide finish. It is a common finishing method used to select nonferrous metal materials, including aluminium, titanium, and magnesium.
As an anodized layer is created from the aluminium itself, it is not applied to the surface like paint or plating but is fully integrated with the underlying aluminium substrate, so it cannot chip or peel, and it is much more durable than any other similar material in the market. The aluminium substrate has a highly ordered, porous structure; thus, it helps the secondary processes such as colouring and sealing.
Different types of aluminium anodizing
There are currently four commonly used types of anodizing; each has its own unique set of functional and aesthetic properties.
- Type I – Chromic acid anodize
This is the most basic type, using chromic acid to produce a thin and ductile anodized layer on an aluminium part.
- Type II – Sulfuric acid anodize
Instead of using chromic acid, Type II utilizes sulfuric acid to produce a thicker anodized layer on a part, making it more suitable for colouration.
- Type III – Hardcoat anodize
Like Type II, this method also uses sulfuric acid but produces a thicker anodized layer suitable for colouration. It’s also commonly known as “hard anodizing”.
- Type IV Chemical Film / Alodine
This method entails coating part with alodine to produce results that are comparable to anodization.
Manufacturers widely used chromic acid to create a thin coating on metal parts’ surface when the anodizing aluminium process was developed in the early 1900s. But nowadays, Type II and Type III are used more frequently as type ll use sulfuric acid to create a slightly thicker surface layer on the aluminium part and type III similar to Type II but results in a thicker corrosion-resistant layer.
Benefits of anodized aluminium
Aluminium is a broadly used material because of its beneficial properties. The primary benefits of anodizing aluminium components are that it offers you greater durability and increased service life. It can also improve abrasion resistance, and corrosion makes this process ideal for parts that will be placed within harsh environments. Here are some more benefits of using anodization on aluminium parts.
- Corrosion Resistance
Anodized aluminium is more resistant to corrosion than standard aluminium. The possibility of standard or anodized aluminium getting rust is quite low. However, it can still rust when exposed to air, moisture, water, salt, or other corrosion-inhibiting compounds or elements. But chances of anodized aluminium corroding are less than standard aluminium because they have a thicker oxide layer.
While the single greatest benefit of anodized aluminium is its superior resistance to resistance, it also provides you with better lubrication than standard aluminium. As aluminium is anodized, it creates deeper pores in the metal that allow for greater lubricating oil or film retention. Standard aluminium has a smooth surface, so it’s unable to retain lubricating oil or film.
Standard aluminium does not support dyeing. As a result, companies that are using standard aluminium are restricted to their natural chrome colour. Thankfully, there is a solution to this problem as anodized aluminium support dyeing and allows you to produce colourful aluminium products. Unlike standard aluminium, anodized aluminium can be dyed to achieve any colour or combination of colours. But how is anodized aluminium able to support dyeing? When aluminium is anodized, it’s exposed to acid chemicals like sulfuric acid that helps you form a thicker oxide layer and a porous surface. The porous surface allows anodized aluminium to hold dye more effectively than the smooth, nonporous standard aluminium surface.
- Increased Adhesion
Anodized aluminium provides greater adhesion for adhesives and primers. It is because the oxide surface of anodized aluminium has deeper pores while comparing to standard aluminium. The pores are mainly holes in which adhesive, primers, or liquids will flow when applied to the surface. As the anodized aluminium nut soaks up the liquids, it allows for greater adhesion.
How to identify if the anodizing is successful?
There are many ways to identify if a part has undergone the anodizing process. First of all, you can easily notice the matte finish that the anodizing process creates. Beyond that, you can use a simple scratch test. Scrape a coin on the aluminium part’s surface, and if a scratch is visible, the part has likely to be polished, not anodized, because an anodized part will be totally scratch resistant.
We hope that you got a fair idea about what is anodized aluminium, its different types, and how it is beneficial from the above discussion.
If you are interested in having your parts anodized, please contact the RapidDirect team or visit https://www.rapiddirect.com/. They have hired highly skilled and knowledgeable professionals in their field and guarantees high-quality aluminum parts to their customers. So, get in touch with them about your requirement. They will guide you through the complete anodized process.