The U.S. Patent & Trademark Office recently published two patent applications from Apple that reveal the composition of and processes used to manufacture the 100% recycled aluminum uni-body enclosure of MacBooks — reports Patently Apple.
Back in 2018, Apple made a giant leap forward in sustainability — the 2018 MacBook Air had an aluminum enclosure made from 100% recycled aluminum, sourced from used beverage cans, that reduced the notebook’s carbon footprint by 50%.
According to Apple’s keynote on the topic, the tech giant achieved this by re-engineering tiny aluminum shavings from used beverage cans down to the individual atom, and shaping the material into an alloy it could use to build the MacBook’s enclosure.
The recently publicized patent applications 20210087656 and 20210087664, titled “Heat-Treatable Aluminum Alloy made from used Beverage can Scrap” and “Cosmetic Aluminum Alloys made from Recycled Aluminum Scrap”, go into detail about how the custom alloys used are made.
In the patents, Apple notes that it is hard to fashion a cosmetically pleasing alloy from recycled aluminum, so the MacBook maker designed a process which would create a ‘substrate’ largely out of recycled aluminum, and fuse it with a cosmetically appealing ‘surface layer’ made from other recycled metals that share some properties with the substrate, creating a ‘clad’.
According to the patents, the clad is created by hot-rolling the surface layer and the substrate together and then cold-rolling the fused clad, before processing it further.
The patents also go into detail about the impurities introduced to these custom recycled alloys to improve constitutional stability, aesthetic appeal, and strength.