iFixit

Though the rear case is the last piece we reach, it's where the design of the new iMac began.

In order to carefully join together the pieces of the case, Apple turned to friction stir welding, a process previously reserved for applications such as ship building and aerospace.

Friction stir welding is more like joining clay than welding—it doesn't melt the workpieces, but rather softens the area between them and forces material together, creating a strong weld with no weakened heat affected zone.

iMac 21.5" EMC 2544 Repairability Score: 3 out of 10 (10 is easiest to repair)

• You can still replace the RAM, hard drive, and CPU inside this machine.
• The glass and LCD are now fused together, and there are no more magnets holding the glass in place. That means it's heatgun time!
• Most replaceable components (like the RAM) are buried behind the logic board, meaning you'll have to take apart most of the iMac just to gain access to them.
• Budget-minded folks can no longer add a second hard drive to the base iMac unless they are super-fond of soldering missing proprietary connectors onto the logic board.
• You'll have to masterfully peel off the old double-sided sticky tape and apply new tape in order to reseal this iMac into original condition.