Couple days ago was officially announced the Apple Watch, the first iteration in a radical new Apple Product line: Watch(es) (From Sport ($349) up to Luxury items ($17.000))
There were many doubts finally clarified, but for me, the most important item which makes a difference against all the current smart-watches available in the market is not its inner electronics or OS ecosystem, but the materials development behind the curtains.
(Note that Apple doesn’t want to refer it as a “smartwatch” but simple as a “Watch”).
I will go one-by-one through them explaining what makes them so special:
The Watch Sport will be made of an aluminum alloy, but not a regular Aluminum alloy. It is a new 60% stronger aluminum alloy (but just as light as regular 6000 series) doped with magnesium and zinc to increase its strength. It is a in-house customized version of the 7000 series aluminum alloy, which has highest strengths of any aluminum alloy. We don’t know the exact elements composition of this Apple Watch 7xxx alloy neither its temper grade, but probably Apple collaborated with some specialized metallurgic company to develop it. These 7xxx series are used in aerospace structures and some of them gets the term aircraft aluminum or aerospace aluminum. It is also used in high performance sports products, particularly snowboards and skis.
For instance, one 7xxx alloy variant called Titanal (composed by Aluminum, Zinc, Magnesium, Copper, Zirconium), and developed by AMAG – (Austria Metall AG) is also used in Consumer Electronics due its excellent properties. But this is not the only one, there are many others as the Alloy 7075.
The only issue with 7000 series alloy is that the corrosion grade is higher than 6000 series, to overcome it Apple applies a critical final step anodizing the entire design, sealing it against with a clear coat. In addition to protecting against corrosion, that coat acts as a barrier to scratches.
Now, you can see as Apple is again one step ahead in Aluminum Alloys usage compared for instance with newest Samsung Galaxy S6 metal phone (take a look to my previous post where I talked about it).
The Watch will be made of stainless steel, but again not ordinary Steel. This new Apple steel alloy is 80% harder, and less susceptible to nicks and scratches; it is the alloy 316L (for instance Rolex uses steel alloy type 940L in their watches). Apple started with a steel alloy known for its durability and corrosion resistance, but after metallurgic research and development they made it even stronger. So, through a specialized cold-forging process, it becomes up to 80 percent harder.
Moreover the space black version gets also a “diamond-like carbon layer“. In this case we have not so much technical details and we will have to wait for the first units to be tested by the end users.
For the most luxury version of the Watch, Watch Edition, Apple invented an entirely new form of gold just for it because gold is a soft metal, susceptible to nicks and scratches. Then, Apple metallurgists engineered an entirely new gold composite (molecules in Apple Gold alloy are closer together, using a novel compression process) that’s up to twice as hard as standard 18-karat gold.
In fact, Apple was granted the 20140361670 USPA patent in December 2014 for creating a “method and apparatus for forming a gold metal matrix composite.” This metal matrix composites allow manufacturers to create complex components, similar to 3-D printing, so Apple could be using this approach to make its special gold:
A metal matrix composite using as one of the components a precious metal is described. In one embodiment, the precious metal takes the form of gold and the metal matrix composite has a gold mass fraction in accordance with 18 k. The metal matrix composite can be formed by blending a precious metal (e.g., gold) powder and a ceramic powder, forming a mixture that is then compressed within a die having a near net shape of the metal matrix composite. The compressed mixture in the die is then heated to sinter the precious metal and ceramic powder. Other techniques for forming the precious metal matrix composite using HIP, and a diamond powder are also disclosed.
Then, after the Metals used, we can also briefly talk about the other external materials used in the three Watch case variants:
Used for the back cover of all Watch models, it’s a type of ceramic non-conductive material, so the inner RF antenna’s (remember Apple Watch has also four wireless interfaces: GPS, NFC, Bluetooth 4.0 and Wi-Fi) can perform perfectly without any interference from the top or bottom crystal surfaces. It’s also opaque, which eliminates cross-talk between the components of the heart rate sensor.
As curiosity, its manufacturing process begins by heating the zirconia at 2640 degrees Fahrenheit for over 30 hours. Once it cools, they incorporate the sapphire lenses of the sensor. Then Apple polish the entire back crystal with a grinding stone to an incredibly smooth, precise finish (with a surface roughness of just 3 nanometers) so that it feels comfortable next to the user skin. I find it quite impressive also 😉 .
The element on which this ceramic composite is based is the Zirconium, and the applications from its composites goes from Industrial Metallurgical furnaces, Ceramic Knifes, up to Space and Biomedical applications.
The Apple Watch Sport will come with an Ion-X front glass, which is lighter than sapphire glass and contributes less to the overall weight of the device. The Ion-X material is an aluminosilicate glass that is “fortified at the molecular level through ion exchange, with smaller ions being replaced by larger ones to create a surface layer far tougher than ordinary glass.” This process creates a material that is resistant to both scratches and impact, which is a major advantage over Sapphire glass (9 Moh). Apple claims it is five times as strong as traditional soda glass, which is mostly silicon oxide (SiO2).
In fact, ionized glass is generally produced by Corning Inc. under the trade-name “Gorilla Glass” as you maybe already known as its typical used nowadays in most of high-end smartphones front/back panel glasses (on the Moh’s hardness scale Gorilla Glass is only around 6 to 6.5).
In the case of Gorilla Glass, this base material is doped by aluminum. It then undergoes potassium enrichment via a hot salt bath during manufacturing process.
The Apple Watch and Watch Edition will come with sapphire glass. Sapphire is hardest, second only (9 Moh) to diamond (10 Moh) on the Moh’s hardness scale, and is extremely resistant to scratches. But sapphire’s Achilles heel is its brittleness, which makes it prone to fracturing on impact. This impact sensitivity is why Apple likely included sapphire in the most expensive Watch models that people will wear for fashion, and not for fitness as the Sport version.