After experiencing market contraction and industry reshuffling in 2015 and 2016, the e-cigarette industry finally reached a new turning point in development in 2017. The global e-cigarette market trend has warmed up, with further growth in sales. Nowadays, e-cigarette casings are becoming increasingly personalized, with more beautiful colors. However, behind this bright appearance lies many complex and cumbersome processes.
The materials used for making e-cigarette casings generally include plastic, stainless steel, aluminum, zinc, magnesium alloy, etc. Today, we will mainly talk about the most commonly used process for making aluminum extrusion profile casings.
Creating a small aluminum casing generally goes through the following processes: mold opening, extrusion, saw cutting, CNC machining (some require stamping, drawing), polishing|brushing, and finally surface treatment, including anodizing or painting, electroplating, ceramic oxidation, etc.
Mold Opening
Molds are high-precision tools designed according to requirements, used for extruding profiles with the required specifications and sections. The design and maintenance should pay attention to the following points:
- The mold structure must first meet production needs and comply with the principles of physics and mechanics, ensuring that the produced product can achieve the desired performance;
- The material selection and hardness of the mold should be appropriate to avoid deformation and scratches during the extrusion process;
- Regular cleaning and inspection of the mold are necessary, with timely repairs to problems to avoid scratches, burrs, and other damages during the extrusion process, severely affecting the quality of industrial aluminum profile products.
Extrusion
The aluminum profile extrusion process considerations include:
- Temperature control: For extrusion production, the extrusion temperature is the most basic and critical process factor, affecting product quality, production efficiency, mold life, and energy consumption.
- Extrusion speed: The extrusion speed must be carefully controlled during the process, as it affects deformation thermal effects, uniformity of deformation, recrystallization and solid solution processes, mechanical properties of the product, and surface quality.
- In-line quenching: Quenching is to retain Mg2Si dissolved in the matrix metal at high temperatures by rapid cooling to room temperature after exiting the die. The cooling rate often correlates positively with the content of the strengthening phase. For the 6063 alloy, the minimum cooling rate for strengthening is 38°C/min, making it suitable for air-cooling quenching. Changing the number of fans and their speed can alter the cooling intensity, ensuring the product temperature drops below 60°C before tension straightening.
- Profile straightening correction: After extrusion, industrial aluminum profiles will have certain deviations and must be straightened and corrected to the required tolerance range using a straightening machine, ensuring precision.
- Artificial aging: Aluminum profiles produced by extrusion have low hardness before aging and cannot be used as finished products. Therefore, they must undergo aging to improve strength.
Careful control is essential in the above processes, as poor control can lead to bright lines, deformation, surface sandholes, and dark lines. Especially for materials with dark lines, if the surface treatment is anodizing, these issues will not be visible until after anodizing, potentially causing significant losses.
Saw Cutting
The freshly extruded profiles are generally 6 meters long, cut into 2 meters or 2.5 meters by the profile factory based on demand and then sent to the aluminum product factory, where they are cut into different lengths according to the drawing dimensions.
CNC Machining (Some Require Stamping)
The lengths from saw cutting cannot meet the drawing tolerance dimensions. These materials must be individually placed on a CNC machine for precision machining. CNC machining involves more than just milling lengths; it also includes machining into different shapes according to product drawings (such as chamfering, drilling, opening windows, etc.), with some products requiring stamping molds for punching to achieve the desired shape.
Polishing|Brushing
After the above four steps, the rough product of the electronic aluminum casing is produced. At this time, the casing surface is dirty and uneven, with many machining burrs remaining, requiring further surface treatment.
- Polishing: A surface modification technology that uses a rough object (sandpaper containing high-hardness particles, etc.) to change the material’s surface physical properties through friction, mainly aiming to achieve a specific surface roughness. Depending on the surface delicacy required for the product, cloth wheels, nylon wheels, flax wheels, and water grinding processes can be chosen. Cloth wheels and nylon wheels are suitable for surfaces with less demanding requirements; higher requirements necessitate flax wheels or even water grinding. Flax wheel grinding uses a lot of wax, so products must be specially cleaned to remove wax. Big companies like iPhone, Huawei, and Xiaomi achieve the polishing effect on their aluminum casings through water grinding, which also means higher costs.
- Brushing: A method that uses a brushing cloth to reciprocate on the surface of the workpiece, improving the surface smoothness and leaving a straight texture, which can improve surface quality and conceal minor scratches.
Surface Treatment
To overcome the deficiencies in surface hardness and wear resistance of aluminum alloys and to extend their application range and lifespan, surface treatment technologies have become indispensable in the use of aluminum alloys. Options include anodizing or painting, electroplating, and ceramic oxidation, among which anodizing technology is the most widely used and successful.
Aluminum anodizing is an electrolytic oxidation process in which the surface of aluminum and aluminum alloys is typically converted into an oxide layer that has protective, decorative, and some other functional properties.