There are several ways to smooth the surface of parts produced in metalworking plants – from classic grinding (mechanical or CNC, using the appropriate grade of tools), to electrochemical polishing.
Each of them gives slightly different results, but the goal is always a perfectly smooth and polished surface. Beyond the visual effect, electropolishing of aluminum alloys to a high gloss using electric current and electrolytes also has many practical advantages that go beyond aesthetic issues (similar to anodizing).
So: what is electropolishing of aluminum and how is it conducted?
What is electrochemical polishing of aluminum?
Electrochemical polishing of aluminum, also known as electropolishing, is an anodic process in which the surface of an object is smoothed during a bath in a galvanic tub.
During this process, the surface of an element develops a thin layer of products with higher electrical resistance than the electrolyte.
The result is smooth, and additionally, no tool marks are visible on it – in addition: it is visually appealing thanks to the mirror-like finish provided by such an electrochemical process.
The mentioned layer is practically partially dissolved material from which the aluminum part subjected to the brightening process is made. This process is often used in situations where it is important to achieve a very smooth surface, and thus – minimize potential friction.
Benefits of electrolytic polishing of aluminum alloys
How to polish aluminum to achieve a mirrored finish? This question often comes up in discussions on forums or groups, both for DIY enthusiasts and professionals.The most effective way to achieve such an effect is through the brightening of aluminum. However, the visual aspect in this case – similar to anodizing – is an additional effect of the process.
The main advantages of subjecting parts to the process of electrochemical polishing of aluminum are:
- Improved chemical resistance, including increased corrosion resistance of the machined metal,
- Reduced friction, important from the perspective of flow or operation of parts in a larger system,
- Removal of thermal and mechanical stresses from the surface, which translates into improved durability of parts,
- Easier cleaning of the metal surface and its more effective disinfection,
- Acceleration of the polishing process of the machined detail, especially in the case of small parts or objects with a very complex shape,
- In many applications – improved visual properties (electropolishing gives much better results than grinding aluminum, even when using special polishing paste with sandpaper with a gradation above 240 and even 1500 grit).
Applications of aluminum electropolishing
Electrochemical polishing of aluminum is particularly useful in applications where it is difficult to achieve a uniformly smooth surface over the entire surface of the element, or where the objects themselves are small and their processing is labor-intensive.
Today, this form of smoothing the surfaces of aluminum objects is used in industries such as:
- Home equipment and bathroom fittings – due to high chemical resistance and anti-corrosion properties, decorative elements and those having regular contact with water are subjected to this process,
- Automotive industry – especially elements of headlights or car rims,
- Various types of packaging, especially for cosmetics (whose composition can cause corrosion of unprotected aluminum surfaces),
- Electronics industry – especially elements of device housings.
Electrochemical polishing of aluminum vs. mechanical: what are the differences?
The biggest advantage of electrochemical polishing of aluminum is the speed of the process, which results from the possibility of automation. The surface is smoothed contact-free, meaning that there is no need for aluminum polishing tools and accessories, such as grinders or polishing pastes.
Another advantage of electrochemical polishing is achieving a uniform surface of the entire element, which is very difficult to achieve when using mechanical tools. Additionally, in this process, there is no deformation of the metal, and no forces act on the object itself that could cause stress.
Of course – electrolytic polishing of aluminum requires appropriate machinery and equipment. Although it can also be carried out at home conditions like anodizing mentioned earlier, for mass production or to achieve the best possible surface – it's worth outsourcing this task to a professional company offering services in both CNC machining and electropolishing of aluminum.
This is all the more justified as automation in production often leads to measurable savings, and an experienced team ensures high quality and repeatability in the electrochemical polishing of aluminum.
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