In this day and age, when user experience is very important, more and more phone, laptop, and wearable device makers are putting effort into the shell materials. Just in the field of mobile phones, engineering plastics are slowly being replaced by metals for the casings of phones. Throughout the history of mobile phone shells, there have been a lot of different combinations, like plastic and metal, glass and metal, all plastic, all glass, etc., but none of them have been as popular as all metal materials. The all-metal mobile phone is better to touch in many ways, and it looks and feels better than other materials.
When we talk about all-metal, we have to talk about CNC. At the moment, CNC machine tools are used to make most of the metal shells for 3C products (Computer numerical control machine tools, CNC). CNC has become an important piece of equipment for companies that make 3C shells because of how fast, accurate, and stable it is.
CNC Machining Process of Mobile Phone Metal Cases
Apple was the first company to use CNC machining on a single piece of metal. Die-casting solid aluminum in the shape of a cylinder is used to make the aluminum plate. After it has been carefully machined, it is first to cut into a model of the one-piece fuselage. As the fuselage takes shape bit by bit, the shape of the keyboard on the fuselage and other small details are milled out. This process has a total of nine CNC milling steps, and at the end, a one-piece shell that is very accurate is made. From programming to getting finished products, shell makers have to go through several steps, such as roughing, semi-roughing, semi-finishing, and finishing. In many cases, the whole process of making a finished product takes more than 10 workstations. If you want to improve the yield, you have to keep strict control over each step.
1. Modeling and programming, which are the first steps in CNC machining
Before CNC machining can start, it needs to be modeled and programmed. The structure of the product determines how hard it is to model in 3D. Modeling a product with a complicated structure is hard, and the procedures that need to be programmed are getting more and more complicated. The process is set up, the tool is chosen, the speed is set, the distance of each feed of the tool is set, and so on. Also, different products have different ways of being clamped, and the fixtures need to be designed before they can be used. Some products with complicated structures need special fixtures. Where do Chinese machines, Japanese accuracy, and German CNC fall short?
Programming includes all of the technology used to process the whole product. Even though CNC automation takes care of the follow-up, the early programming must be done by people with experience to avoid a lot of trial and error, which would drive up costs.
2. Main processing technology: Using a high-speed drilling and tapping center to mill the aluminum sheet into a regular three-dimensional volume of a certain size, so it’s ready for the next step.
– Rough milling: After positioning, the inner cavity structure, the positioning column combined with the fixture, and most of the extra materials on the outside are milled away.
– Cutting the slot for the antenna: It is hard to get a signal through the all-metal case. You have to mill out the antenna slot to leave a path for the signal to travel, and you have to keep the necessary connection points to make sure the body is strong and stays together.
-CNC finishing: milling the inside of the cavity, the outside of the structure, the outside surface, the side edge, etc.
-Polishing: Polishing with a high-speed, precise CNC machine to get rid of knife lines and get ready for the sandblasting that will come next.
– Sandblasting: Give the surface of the metal a frosted look.
Anodizing changes the color of the phone and turns the aluminum into gold. At the same time, make the surface material more stable.
Secondary anode: An oxide film that is hard and dense forms on the surface of the fuselage, which makes it even more resistant to wear.
-The plastic shell is made with a process called injection molding. The mold has to be opened in order to make a lot of them, but the yield is very high. How well the all-metal body can be machined with CNC depends on how complicated its structure is and how precise it needs to be. Like a plastic casing, it is hard to get a high yield. When there is a price war, most companies that make things will choose to buy to make up for the high costs. A lot of CNC equipment to cut down on costs overall and meet the needs of productivity.