Anodizing is an important step in manufacturing stainless steel components. It helps to increase the thickness of the natural oxide layer and improve durability. You can also use it to enhance aesthetics and to protect the part from hostile environments. Anodized steel parts maintain their quality and function perfectly under challenging conditions.
To get maximum benefits from anodizing, you have to be familiar with the process. If you want to know the steps to take to get high-quality anodized components, you are not alone. This article will be your guide. It will explain what stainless steel anodizing is, how to carry out the process, and the differences between shop and DIY anodizing.
What is Stainless Steel Anodizing
Anodizing stainless steel is an electrochemical process that involves applying a durable anodic film on a part. The chromium oxide layer is thin and ranges between 10 to 50 microns depending on the types of anodizing. To carry out anodizing, you immerse the workpiece in an electrolyte solution and then pass electricity through it.
Note that not all stainless steel is suitable for anodizing. You might want to limit it to austenitic stainless steel because of the high chromium and nickel content. Chromium and nickel enhance the formation of a stable protective layer. They prevent the part from corroding during electrochemical reactions.
How to Anodize Stainless Steel
You can anodize stainless steel by following the four steps below
Step 1- Pre-treatment
The pretreatment phase is a very important step as it will determine the quality of the anodized part. Firstly, clean the surface of the steel workpiece using water or alkaline-based cleanser to remove dirt and dust. You can then use a degreaser to remove grease, oil, and lubricants that can interfere with the operation.
Thereafter, you chemically etch the stainless steel workpiece by dipping it in an acidic solution, usually sulfuric or hydrochloric acid. This etching time varies and depends on the state of the workpiece surface. Chemical etching removes free oxides and the exterior so the anodizing solution can penetrate. You then rinse off any excess chemicals. If there are visible scratches or imperfections, it is important to polish them using sandpaper or buffing wheels.
Step 2- Anodizing
Mix water and sulfuric acid to get the desired concentration and fill the anodizing tank to the required level. Carefully place the stainless steel part into the electrolytic solution and connect the power source. The part serves as the anode while the cathode is usually platinum or titanium.
Once electric current flows through, reduction occurs, and the ions migrate to the anode. Here, they combine with metal ions forming a protective layer. You then allow the oxide layer to grow uniformly at a constant temperature and voltage. The anodizing time depends on the thickness level you want to achieve. After anodizing, take out the final part and clean.
Note: Continuously monitor the process and agitate the solution at intervals to prevent localized build-up.
Step 3- Coloring
Now that you have your anodized stainless steel part, the next step is to color it. Choose an appropriate dye and dissolve it according to the manufacturer’s instructions. Thereafter, heat the dye mixture slowly at a specific temperature. After, place the anodized part in the dye tank for some minutes. Revive and rinse when you are done.
You can also color the anodized parts using electrolytic salts such as nickel acetate or copper acetate. You first immerse the part into the solution and allow it to soak for time. Pass an electric current and increase the voltage over 60 seconds. The reaction deposits metal ions that react to produce a color. The final color depends on the type of salt and coloring time.
Step 4- Sealing
Sealing is the last step in stainless steel anodizing. This step helps to enclose the pores of the porous oxide layer. You can either seal at room or high temperature. Hot sealing is an old method that uses nickel compounds as the sealant. You carry out this process at about 97 degrees Celsius. At this high temperature, the pores open fully and the sealant fills them up. However, hot sealing is not environmentally friendly because the nickel compounds are toxic. The second type is cold sealing. It is done at lower than room temperature. Cold sealing produces less toxic waste and is safer.
Importance of Anodizing Stainless Steel
There are many benefits you stand to gain from anodizing stainless steel. This process improves the functionality and performance of parts. The following are some importance of stainless steel anodizing
Aesthetic Appeal
The outer appearance of a part is the first thing customers notice. It determines how they perceive your product and may influence purchasing decisions. The process of coloring after anodizing makes parts attractive and more appealing. There are different grades and shades of color you can use to get a sleek appearance.
Corrosion Resistance
The anodizing process protects the underlying stainless steel part from corrosive attack. The thick final oxide layer offers greater protection and provides a barrier against corrosion. Furthermore, the sealing step reduces porosity and prevents the entry of corrosive substances.
Ease of Maintenance
The final surface finish of the stainless steel anodized part is smooth and sleek. You will find it easy to clean during routine maintenance. Since anodizing reduces rust, you may not have to use rust removals during cleaning. Additionally, anodizing reduces wear and elongates the lifespan of the parts.
Reduced Risk of Delamination
Delamination is a common coating defect. This occurs when the coating separates from the base metal. Anodizing prevents this because it creates a strong mechanical bond between the stainless steel part and the coating. The coatings adhere and do not detach even after prolonged use.
Anodizing Stainless Steel DIY Vs Shop; Which is Better?
You can either carry out anodizing yourself or with the help of a professional. Let’s look at how both compare to determine which is better
Cost
Shop anodizing is generally more expensive than a DIY process. This is because the equipment used is heavy and pricey. The amount they charge depends on the size of the part, the complexity of the project, and the quantity. There may be additional prices if that part comes with special requirements like customization or personalization.
Quality
The quality of the final part from shop anodizing is considerably greater than that of DIY. Most anodizing service providers control the entire process to meet the highest quality standards. Some even have certifications to ensure compliance with industry specifications. With shop anodizing, you can be sure of a durable and high-performance component.
Time and Effort
The time and effort are other ways you can differentiate between anodizing shop and DIY anodizing. DIY takes more time, mental effort, and physical labor. With shop anodizing, all you need to do is request a quote, drop the part, and pick it up when it is ready. You don’t have to worry about the process or details.
Consistency
With shop anodizing, you can be sure of process consistency. With a good service provider, you will achieve a uniform thickness that is free from variations. Furthermore, the final finish and color shade are the same throughout. Consistency boosts customer satisfaction and guarantees performance.
Color Options
Shop anodizing provides more colors you can choose from. The most common are transparent, gold, brown, and black. You can also request for others based on your project requirements. Note that the cost of coloring may vary based on the type of dye you are using.
Expertise and Experience
Shop anodizing gives you access to experienced operations and engineers. They are vast in anodizing and familiar with the different stainless steel alloys. They troubleshoot and resolve issues efficiently to produce high-quality products.
Warranty
A reliable anodizing service provider will include a warranty on their package. In cases of issues after production, you can still reach out for a specific period. They will help tackle problems easily and get you back on track. DIY is like trial and error with no insurance. If there are mistakes, you may have to face them alone.
Conclusion
Stainless steel anodizing is a vital process in many manufacturing industries. You can use it for automotive components, parts of food processing equipment, solar panels, and medical devices. Though DIY may be more affordable, shop anodizing provides more benefits in the long run. With shop anodizing, you can process large parts and be sure of consistent results. This article has explained what stainless steel anodizing is, its importance, and how to carry out the process.