New iPhone - the metallurgy

Posted by Boghog on September 1, 2012 09:12 am 18

As someone who works in engineering/manufacturing, I'm very interested in what Apple are doing with the construction of the new iPhone.

Unibody phone aren't new but the previous ones have been made in aluminium, either machined or cast (or a combination) or from plastics like polycarbonate

It appears the new iPhone follows the 4/4S in using Austenitic stainless steel but rather than just the outer ring, it is most of the body.

The picture above and many similar ones poses a few questions to the engineering mind.

Despite what many people think, stainless steel is actually relatively soft and scratches easily (unless you use duplex which is horribly expensive and hard to machine) . Not as much as bare aluminium but you will easily scratch it with some sand, grit in your pocket or the gems on a ring. Aluminium is normally anodised which puts a hard coating on it to stop scratching. A similar process can be done on stainless steel and would account for the matte finish on the back and side above but not the highly polished edge which is a nice style link to the 3GS.

Then I remembered this patent from a couple of years ago. This talks about leaving a metallic gold colour but Apple may have found a way to change that or include a dye (as you can with anodising) to get the back and silver versions but still have the highly polished edge

The other interesting bit is the breaks in edge which mirror the breaks in the antenna band on the 4S. It may be that these are just stylistic to carry over the line of the screen at the front and the glass/plastic at the back but maybe they are still antennas and the end sections are actually separate from the main body.

Anyway, it's an interesting device and I cant wait to see when iFixit take it apart