Full CNC process? die-casting? CNC + die casting?
Before restoring the manufacturing journey of mobile phone shell, let’s clarify several concepts: full CNC process and die-casting process, and CNC + die-casting. The middle frame of full CNC mobile phone is milled into a specific shape through the CNC machining center. Die-casting is to use the mold cavity to apply high pressure to the molten metal and die-casting the fluid metal into a solid metal shell or middle frame, Of course, there is the practice of combining the two processes.
Think about it with the appendix. The cost of full CNC process is relatively high and there is a lot of material waste. Of course, the quality of the middle frame or shell under this process is better. The principle of die casting is not to waste and save time and cost, but it is not conducive to the later anodizing process, and may leave sand hole flow marks and other small problems affecting quality and appearance. Of course, manufacturers have a concept of good product rate, and reliable manufacturers will not let these inferior products flow into the later production links.
After understanding the similarities and differences between the two processes, we began to talk about the metal shell processing technology that is also emerging on the thousand yuan machine. After the indiscriminate bombardment of various tall mobile phone press conferences, I believe everyone can break their fingers. Today, there is no dog tail mink here. Today, let’s talk about the whole process of die casting + CNC process of metal mobile phone shell:
1、 Die casting stage
Before die casting, what we see is the original aluminum. Because the strength and hardness of pure aluminum are not enough, in fact, all aluminum alloys used in mobile phones have different characteristics according to different formulas. For example, the 6000 series aluminum alloy used for iPhone 6 is not strong enough, but it has better ductility and is easy to be bent. The 7000 series used in the iPhone 6S has much higher strength, but it is more brittle. It is more difficult to be pressed and deformed, but once it exceeds the stress load, it will not bend, but break.
Well, according to different manufacturers’ demands, the formula of aluminum alloy is also different. For example, the aluminum material below is added with precious metals such as rare earth, titanium and cobalt. Of course, the proportion of these precious metals is very low, and they are actually not so expensive compared with real precious metals such as gold and platinum.
Since it is die-casting, it is impossible to directly cut the aluminum, but it needs to melt the aluminum into a fluid to facilitate subsequent stamping in the mold, so the picture below is with temperature.
When these metals become fluid, it’s time to inject them into the die casting machine. This is the most difficult moment in aluminum’s life. The aluminum water flows slowly from the cobweb groove, receives unimaginable stamping, and finally becomes the prototype of a shell. Although it seems relatively simple, even in such a link, we should always prevent sand holes in shell processing. Once there are sand holes, there will be small pits in subsequent processing and cutting. Therefore, we still need to improve the process and mold structure. A lot of raw materials will be wasted in the process of trial and error improvement.
When strands of molten aluminum are pressed one after another, the manipulator will peel off the rough shell and send it to the assembly line for the next round of test.