Originally Posted by WelshDog
I mean, we know they aren't welding the case shut! So what is it used for?
It does appear to be used for welding the front and back together:
"That required unprecedented feats of engineering," Apple notes, including the challenge of attaching the front and back case components together.
Conventional welding wouldn't work, so the company switched to a process known as "friction-stir welding," which it says "uses a combination of intense friction-generated heat and pressure to intermix the molecules of the two aluminum surfaces — creating a seamless, precise, and superstrong join."
I understand their desire for a seamless design but I thought the 2009 iMac looked fine even with the black back:
and the rMBP base looks fine too:
The iMac wouldn't even have screws on the back.
I guess the plus side to this is if the front plate falls off, it will be easier for people to repair/upgrade.
Of course if they got rid of the chin, there wouldn't be a front plate needing to be welded in the first place. It would just look like the iPad and Cinema Display. The display can be held in with a wedge of metal at the top, magnetic strips left and right and screws at the base.