When it comes to surface finishing techniques, it is no surprise is anodization comes to mind first. The popularity of this process is increasing daily because of its benefits. Anodizing results in a part that is strong and corrosion-resistant. The extra aluminum oxide layer increases the aesthetics and overall performance of a product.
However, how long does the anodization process take? The time it takes to complete the reaction differs and depends on many factors. Read on to find out all about aluminum anodizing, factors that affect anodization time, and how to optimize the process to reduce the time spent.
What is Anodization
Anodization or simply anodizing is an electrolytic passivation process that increases the outer layer of a metal workpiece. This extra layer grows out which makes it durable and scratch-resistant. While anodization is commonly associated with aluminum metal, it is a versatile process and is ideal for different engineering materials. Examples of metals that can undergo the anodization operation include stainless steel, magnesium, and titanium.
The process of anodization begins with preparing the surface of the workpiece. You do this by cleaning all forms of dirt and contaminants. The next step is to get the electrolytic bath which can be sulfuric acid or chromic acid. Thereafter, submerge the workpiece in the electrolyte bath and pass an electric current. As the current passes through, oxygen atoms migrate to the surface of the workpiece to form an oxide layer. You then add a suitable dye to color the part. Seal everything by dipping the part in a solution of nickel acetate.
How Long Does Anodization Take
The process of anodization from workpiece preparation to coloring and sealing can be time-consuming. The time anodization takes differs and depends on many factors including the thickness of the oxide layer, particular metal alloy, electrolyte composition, current, and temperature conditions. Let’s look at these factors in detail
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Thickness of the Oxide Layer
The time you spend on anodizing depends on how thick you want the oxide layer to be. On average, the layer grows at a rate of 5-10 micrometers per hour. Thin coatings will take less time to develop when compared to thicker ones. Note that the level of thickness you go for depends on your aim. For decorative purposes, you can stick to thin coatings. Thicker ones are better when considering functionality.
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Electrolyte Composition
The type and concentration of the electrolyte you are using is another important factor. The electrolyte can be sulfuric acid, chromic acid, or oxalic acid in rare cases. Sulfuric acid is the fastest of the three types. Using it takes less time as the oxide layer builds up quickly. Furthermore, the concentration you use is important. Increasing the concentration of the electrolyte makes the process slower.
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Metal Alloy and Composition
The composition of the metal alloy will also determine reaction time. Pure aluminum such as 1050 and 1100 anodizes quickly. You will find the oxide layer growing at a fast rate. For aluminum alloys containing nickel, iron, or chromium, the reaction rate is slower. It is more time-consuming to achieve the same layer thickness when compared to high-purity aluminum.
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Current
The current and voltage of the process plays a key role in the anodizing rate. When using a high current, you can be sure of a faster reaction time. With a low current, the growth rate is slower. However, you should not increase the current arbitrarily. Too high a current will not give the oxide layer enough time to form. Additionally, the process will lead to excessive heat generation which can damage the workpiece.
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Temperature
The temperature of the bath determines how well the oxide layer forms and the time it takes. At lower temperatures, the resulting layer is strong and thick. However, the process occurs at a slower rate. As you increase the anodizing temperature, the duration of the process becomes shorter. This comes at a cost. The final layer is softer and more porous.
How to Reduce Anodization Time
The following are some strategies you can employ to reduce anodization time and improve productivity
- Preheat the workpiece before anodization to hasten the electrochemical reaction.
- Consider including additives such as surfactants, organic acids, and hardness enhancers in the electrolytic bath. These additives reduce reaction time and form dense oxide layers.
- You can also agitate the bath occasionally as the oxide layer grows. This will ensure that the concentration of the oxygen ions is consistent all through.
- Prioritize the use of high-purity aluminum over those with alloying elements.
- Ensure the concentration of the electrolyte you are using is optimal. With this, you can be sure of a reduced anodization time.
- Control the temperature of the bath and adjust it to increase the reaction rate.
Applications of Anodization in Manufacturing Industries
Anodizing is the mainstay surface finishing technique in many industrial applications. The parts are durable and of a high quality. Let’s look at common manufacturing industries that use anodization extensively.
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Aerospace Industry
Anodization is an important step when manufacturing aerospace components such as wings and engine components. This is because these parts are often subjected to high stress. The use of anodizing not only enhances performance and durability. The parts can be dyed into different colors to aid customization and brand identification.
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Automotive Industry
The use of anodization in the automotive industry is nothing new. Anodized parts are exceptionally hard and impact-resistant. With them, you can be sure of the safety of passengers and loads. Furthermore, aluminum anodized components including interior components and fuel systems reduces the overall weight of the car. This increases fuel efficiency and lessens the cost of operation.
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Marine Industry
Anodized aluminum is a popular choice for manufacturing boat and ship parts. The reasons for this are not far-fetched. Anodized components are resistant to corrosive attacks. They can survive the saltwater environment for a long time without breaking down. Furthermore, they have low maintenance requirements and you can easily clean them.
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Medical and Dental Applications
Anodization plays a huge role when fabricating medical and dental equipment. Anodized aluminum is safe and does not react with bodily fluids and tissues. The parts are durable and wear-resistant. Examples of these components include surgical instruments, orthodontic tools, and parts of big machines.
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Food and Beverage Industry
The anodizing process is key when manufacturing components used in the food and beverage industry. The protective oxide layer and non-stick surface make it possible to use aluminum for cookware. Anodized aluminum also has applications in parts of food processing equipment and beverage containers. These components are durable and hygienic.
Conclusion
In manufacturing, time is of the essence. While anodization offers unwavering benefits, it adds to the total machining time and may increase labor costs. The time spent to produce anodized aluminum depends on the level of thickness you want to achieve, metal composition, current, and temperature of the bath. To reduce anodization time, you can preheat the workpiece to increase the rate of reaction and agitate the bath occasionally. Do you have further questions and clarifications? Reach out to a reliable custom part manufacturer today.
