In this era when user experience is highly valued, more and more manufacturers of mobile phones, notebooks, and wearable devices are beginning to make efforts on shell materials. From the mobile phone field alone, the material of mobile phone shells is gradually transitioning from engineering plastics to metal. During the evolution of mobile phone shell materials, there have been many combinations: plastic and metal, glass and metal, all plastic, all glass, etc., but in the end none of them overwhelmed the limelight of all metal materials. From the actual touch experience, the all-metal mobile phone does have an outstanding experience in many aspects, and it is better than other materials in terms of appearance and feel.
At present, all metal shells of 3C products are basically processed by computer numerical control machine tools (CNC). CNC has become a necessary equipment for 3C shell manufacturers due to its high efficiency, high precision, and stable processing quality.
The all-metal integrated CNC machining process was first pioneered by Apple-the aluminum plate is die-casted from columnar solid aluminum, and is cut into the prototype of the integrated body after precision machining. As the body gradually takes shape, the keyboard shape on the body And various fine structures are milled out. This process includes a total of nine CNC milling processes. After nine processes, a precise one-piece shell is obtained.
Aluminum CNC machining technology
The process steps that need to use cutting tools are:
Rough milling of the inner cavity: rough milling the contour shape of the inner cavity of the mobile phone shell, and process the inner cavity and the positioning column combined with the fixture, which is very important for the subsequent processing links.
Milling antenna slot: Metal aluminum can shield (weak) the radio frequency signal of the mobile phone, so it must go through the method of slotting, so that the signal can have a path in and out. Therefore, milling the antenna slot is the most important and difficult step. The antenna slot must be milled uniformly and the necessary link points must be maintained to ensure the strength and integrity of the metal shell.
Precision milling arc surface: 3D shaping of the metal aluminum alloy body, usually using CNC machining center to mill the arc surface contour, which is also the most time-consuming process.
Finish milling the side: The 3D arc of the metal body is milled out by CNC, but there is still a circle of redundancy at the edge, so the finishing process of side milling is required, and then the prototype of the metal shell can be seen.
Polishing: Use high-speed and precise CNC machine tools, but it can only achieve A1-A2 level finish. To meet the subsequent processing requirements, it needs to be polished to A0 level finish, which can have a mirror effect.
Highlight: Use high-grade ultra-high-speed CNC machine tools to cut corners. This process is also called drilling or highlighting.
Finish milling the inner cavity: After the aluminum alloy has been processed in multiple steps, the metal shell has been formed, and then the extra materials such as the positioning posts used for fixture locking are removed to make the metal shell completely clean.
Conductive milling: The conductive effect of the aluminum alloy shell after anodization will become worse, so it is necessary to remove the local anodized film to expose the metal to obtain a good grounding effect, and it will also need to undergo CNC processing for milling the conductive site again .
Polishing: Polishing refers to the use of mechanical, chemical or electrochemical effects to reduce the surface roughness of the workpiece to obtain a bright, smooth surface. The conventional polishing process is mechanical polishing and chemical polishing. High-speed precision CNC machine tools are used for mechanical polishing to eliminate knife marks and prepare for subsequent sandblasting.