Anyone with half a brain...
does both non-destructive and destructive testing on their products and components before they assemble them.
For a company (Apple) that make laptop frames from magnesium, it's difficult to understand why they chose aluminum for the iPhone.
No one has mentioned heat treating for the iPhone frames but improper heat treating (annealing) aluminum will change it's mechanical properties dramatically. Improper metallurgy is another potential issue, especially when sourced in China. In most cases, machining from billet aluminum leaves the product with brittleness not softness. Typically, heat treating makes an aluminum or non ferrous products more ductile. Then it should get re-hardened by soaking it in hot fluid. Sometimes you use age hardening but that takes time the manufacturer might not have had.
If this is the result of a manufacturing shortcut then I'll bet there will be hell to pay for it.
Biting the hand that feeds IT
