The Benefits of Surface Finishing for Aluminum Parts CNC Machined
Aluminum is a highly significant material that finds extensive usage across diverse industries for various applications. Its distinct benefits, including low density and excellent corrosion resistance, have made it an indispensable element in various sectors, including Aerospace, Transportation, and Building. As a result, aluminum has become the cornerstone of these industries.
This article will concentrate on the significance of a particular metal, namely aluminum. It will delve into aluminum machining, then explore the surface coating techniques employed for aluminum.
Introduction
Due to its exceptional lightweight, malleability, and flexibility, aluminum is an ideal material for machining procedures, which is why aluminum processing is prevalent in a wide range of industries. In this segment, we will discuss the essential variables that necessitate attention when undertaking aluminum machining.
- Important Properties: Aluminum alloys possess a density that enables high rotational velocities, and their thermal conductivity facilitates heat dissipation. However, the modulus of the flexibility of aluminum necessitates appropriate and precise chucking & clamping arrangements to prevent distortion and deformation.
- Cutting Force: Aluminum needs less force to cut than steel. It means that when cutting aluminum, more chips are produced than when cutting low-carbon(mild) steel of the same thickness.
- Lubrication: Lubrication serves two purposes during machining. First, it aids in the effective dissipation of heat. Second, it helps prevent swarf, the small chips created during machining, from sticking to the equipment and facilitates easy removal of swarf from the machining point.
Once aluminum processing (machining) is finished, attention must be paid to its surface finish. Different post-processing techniques can enhance the surface coating of aluminum. In this section, we will discuss the primary methods and their aluminum application, one by one.
5 Methods to Finish an Aluminium Parts CNC Machining
When selecting materials for your CNC machined parts and prototypes, aluminum alloys are frequently an excellent choice. Depending on the selected alloy, they offer a variety of physical & mechanical properties, and aluminum units can be coated in various ways. Here, we’ll discuss the five most prevalent finishing methods.
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As machined
Leaving parts in their original state immediately after machining in the CNC center is a straightforward option that may suffice for prototypes or units that don’t require a specific appearance or scratch/abrasion resistance. However, with careful selection of tools, alloy, and cutting conditions, “as machined” units can look excellent without further finishing steps. Check out “Parts Gallery” for examples of our “as machined” job.
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Glass bead & sandblasting
Bead blasting is the coating (finishing) method that uses a high-pressure air gun to blast small glass beads onto the machined part. The process eliminates smears, contaminants & embedded media from the impacted surfaces, smooths high points, and seals pores. A range of coatings from matte to satin can be achieved.
The media’s peening action also applies a surface compression layer on the part’s surface. It enhances surface strength, enhances fatigue life, and reduces the part’s susceptibility to stress-assisted corrosion. However, it’s recommended to avoid using this process when a part’s dimensional tolerances/specific properties are critical.
Similarly, sandblasting involves high-pressure abrasive blasting to cut away material and is, therefore, more aggressive than micro-abrasive blasting.
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Electroplating
It is a popular method of finishing metals that enhances corrosion protection and wear resistance/increases the product’s appearance. This method involves immersing aluminum components in the electrolytic medium. This process requires passing an electric current through a solution containing ions of a different metal, which then get deposited onto the surface of an object. Silver, nickel, tin, and gold are common metals used for plating.
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Anodizing
The electrochemical technique provides extra protection beyond the natural oxide layer that forms on aluminum & its alloys. This process creates a robust, porous anodized layer on the aluminum surface. It is dyeable to give your parts a wear-resistant color.
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Powder coating
It is a process where a part is coated with a polymer powder utilizing the electrostatic painting gun and then cured in an oven at around 200°C. This method enhances the strength & wear properties of a unit and its corrosion & impact resistance.
Top Tips for Surface Finishing for Improving Aluminum Parts Value
Improving the Aluminum’s Corrosion Resistance
When air exposure, aluminum reacts with oxygen to create a thin oxidation layer. This oxide layer provides excellent corrosion resistance. However, further surface finishing can enhance this property. The kind of surface finish depends on the Intentional use and desired quality. Chemical conversion, anodizing, and plating can all improve corrosion resistance.
Improving the Resistance and Strength
Although aluminum is a sturdy metal suitable for use in structures, it also has a soft nature. To increase its strength, heat treatment can be employed, but the surface coating is necessary for further hardening.
The hardness of aluminum’s surface is increasable to HV200 with regular anodizing, HV400 or higher with hard anodizing, and HV800 or higher with nickel chrome plating. However, the hardness level may vary depending on the type of aluminum material used.
Increasing the hardness of aluminum by surface finishing leads to an increase in the film’s mass, which improves wear resistance. Aluminum’s lightweight makes it ideal for fast-moving parts or those with low energy consumption. Additionally, coating aluminum with materials like PTFE can enhance its lubricity and slidability.
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Adding Aesthetic appearance
Aluminum has a nice appearance, but anodizing & plating can make it look even better.
By plating it with different metals and finishes and anodizing and dyeing it, we can create a variety of colors with an amazing metallic texture that complements the specific kind of aluminum composite being useful.
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Using high conductivity
Aluminum is a metal that transmits electricity well, but it can become resistant if left untreated due to the oxide film that forms on its surface. To fix this, plate a low-resistance metal film onto the aluminum to improve its electrical conductivity while keeping it lightweight.
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Adding solderability
Aluminum is a popular choice for making lightweight and easy-to-process parts. However, it is not soldering in its natural state. To solve this problem, a plating good for soldering is useful for aluminum parts to make them solderable.
Nickel & tin plating are commonly useful for soldering because they have good solder wettability.
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Improving the shielding performance
To improve the electromagnetic wave shielding performance of aluminum, a copper electroplating process can be used. This process has been widely used due to its ability to enhance shielding performance across various frequencies.
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Using aluminum’s excellent thermal conductivity
Aluminum has excellent thermal conductivity, ranking fourth among all metals. Due to its lightweight, it is commonly used as a heat-dissipation material.
Anodizing doesn’t enhance thermal conductivity in aluminum. In reality, the anodized layer is less thermally conductive compared to the original aluminum material.
An anodized aluminum finish is preferred for thermal sinks because it enhances the radiation rate & improves the thermal dissipation capability.
The choice between increasing the radiation rate or using the material’s thermal conduction performance relies on the specific usage environment.
The performance of anodizing varies based on its width and the type of aluminum used. For those who wish to utilize the natural performance of aluminum, we recommend using chemical conversion instead.
Conclusion
Aluminum surface coatings can help you get more value from your products. Although mill-layer aluminum is initially less expensive, aluminum without coating products should work replaceable more frequently in applications where corrosion & wear issues. As a result, opting for surface finishes can lead to cost savings.
To enhance the appearance of your design, it’s essential to give proper finishing to the extruded aluminum surface. You can use different finishing processes, depending on your requirements, and even combine them to get the advantages of both.
Creatingway can assist in product rollout planning and propose specifications that meet the customer’s requirements while keeping prices low. We have expertise in aluminum properties & surface finishing, allowing us to suggest solutions that add value to aluminum parts.
Creatingway concentrates on CNC manufacturing, prototype machining, low-volume manufacturing, metal fabrication, and parts finishing services, providing you with the best support. ask us one inquiry now.
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