[akshed]

Hi, I'm Anna Shedletsky, the author of the post linked above. I spent six years as a product design engineer at Apple, designing very similar products and making similar design decisions that Samsung engineers needed to make.

Typical smart phone / tablet type products use a stamped metal frame ($) to stiffen the product and support the display. A few phones use die-cast magnesium frames ($$). A CNC'ed pocket ($$$$) is a significant cost adder for this product (larger starting billet, longer cycle time, and thousands of CNC machines required) -- so this choice was clearly made for a reason.

Additionally, the fact that the battery is surrounded on five sides by a machined pocket cuts into battery volume -- most products just rely on an air gap (0.5-1mm) between the battery pouch and the next nearest component that could poke it during assembly and usage. Take a look at some other product teardowns on iFixit, and you'll see this (example from iPhone 7: https://d3nevzfk7ii3be.cloudfront.net/igi/fJI2bhqYXg4CMNPi.h...)

They added significant cost to the product and sacrificed a little battery capacity to have that pocket. I hypothesize that it was for battery safety given the aggressive design.

[burfog]

What about forging? Rough out the shape from AlZnMgCu1,5 (EN AW-7075) alloy, heat to 450°C, and slam it between a pair of dies.

Compared to cast or machined parts, you get a 20% higher strength-to-weight ratio from the forging. The cycle time is decent I think, perhaps 3 per second with a 0.06 second contact time in the dies.

[mritun]

Tolerances are poor with forging.