Mar 10, 2016 | By Kira
The US Patent and Trademark Office today published a patent application from none other than Apple Inc., describing a new method of forming electronic device components using liquid metals and 3D printed investment molds. The proposal, which follows a previous patent application for a full-color 3D printer, is yet another strong sign that 3D printing is making its way into the very highest areas of technology manufacturing.
Apple’s patent application covers a method for 3D printing investment molds to be filled with molten amorphous alloy. These alloys are configured to form a bulk metallic glass (BMG) on cooling. BMGs, (also known as Bulk Amporhous Alloys) are a new class of metallic alloys that are extremely strong, with superior elastic strain limits and resistance under shock impact. They are therefore ideal for the manufacturing of electronic device housings and cases.
What takes Apple’s invention beyond a being mere 3D printed mold is the fact that this method could be used to replace costly and wasteful traditional investment castings, the most common way to mold liquid metals, and more specifically, amorphous metals, today. Traditional investment casting—which is also one of the oldest manufacturing processes—usually involves pouring liquid metal into a ceramic mold. Once the liquid metal is cooled and solidified, he mold is stripped away, and the cast metallic piece is ready for use or for further processing.
This process has two significant disadvantages: cost and material waste. When it comes to bulk-solidifying amorphous metals, another issue can be introduced: as Apple explains, BMGs’ unique structural properties come from their non-crystalline (i.e. glassy) state. In order to retain that state, the liquid alloys must be solidified and cooled at relatively slow rates. However, “if the cooling rate is not sufficiently high, crystals may form inside the alloy during cooling, so that the benefits of the amorphous state are partially or completely lost. For example, one risk with the creation of bulk amorphous alloy parts is partial crystallization due to either slow cooling or impurities in the raw material.”
Thus, Apple needed to find a way to mold amorphous, glasslike alloys while reducing cost, reducing material waste, and maintaining an optimized cooling rate, also known as the “critical cooling rate.” If this patent application receives approval, 3D printing could be the answer.
a first perspective view of the exemplary investment mold with a funnel attached to its seat for a crucible tube
perspective view of the cross-section of the mold and funnel with molten alloy therein
By 3D printing the investment castings, Apple would eliminate the need for costly materials such as ceramic while still creating molds suitable for amorphous alloys. 3D printing also reduces lead times, and allows for the rapid prototyping of several investment molds at a time, giving Apple much-needed flexibility in its product development process.
When it comes to addressing the issue of the critical cooling rate, Apple’s patent application outlines potential aspects for removing unwanted bubbles and crystals, such as quenching the molten alloy while it is still inside the 3D printed investment mold, or removing the BMG product from the mold only after the molten amorphous alloy as cooled.
flow chart illustrating exemplary steps in a method of forming a mold using a 3D printing process and a method of using the mold
These molded BMG products can be used in everything from digital displays to TV, tablet or computer monitors, endowing them with their uniquely strong and impact-resistant properties. They can also be incorporated into smartphones, DVD players, video game consoles, music players, remote controls, or just about any electronic device you can think of.
Interestingly, this is the second Apple patent application recently published that has to do with liquid metal. A separate proposal suggests that Apple might soon use actual LiquidMetal—a patented material that Apple bought the exclusive rights to several years ago—in the iPhone’s home button, giving flexible strength to the essential component.
Apple’s patent application for 3D printed investment molds for casting of amorphous alloys can be read in full via the U.S. Patent Office. Granted, since it is still only an application and has been filed for over a year now, there is no saying if it will actually receive approval, nor when Apple would see fit to put it to use.
Posted in 3D Printer Company
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yzorg wrote at 3/11/2016 11:13:31 AM:
ugh, please Apple... stop filing masses of patents with no actual Product. You guys at Apple should rather make some effort to bring back up a useful und reliable Hardware Software Combo... Bring the Macs back to beeing best solution for Musik and Designstudios. Because thats definitely not the case anymore..