Tesla files another casting patent application

Invents new aluminium alloys for die-casting electric car parts. The “high-performance die-castable aluminium alloys” described by Tesla also have “a high flowability and low susceptibility to hot tearing when die-cast.”

Tesla has filed another patent application to do with a metalcasting invention, this time for aluminium die-casting alloys. Last summer, the company had filed a patent application for a multidirectional unibody casting machine for a vehicle frame and associated methods.

In this more recent application, Tesla claims to have invented new aluminium alloys with both high yield strength and conductivity as well as improved castability.

From the claim:
Commercial cast aluminium alloys fall into one of two categories – either possessing high-yield strength or possessing high-conductivity. For example, the A356 aluminium alloy has a yield strength of greater than 175MPa, but has a conductivity of approximately 40% IACS. Conversely, the 100.1 aluminium alloy has a conductivity of greater than 48% IACS, but a yield strength of less than 50MPa.

For certain applications, for example, parts within an electric vehicle like a rotor or an inverter, both high strength and conductivity are desired. Further, because it is desired to form these electric-vehicle parts through a casting process, wrought alloys cannot be used. Rather, it is desirable to form the parts through a casting process, such that the parts may be cast quickly and reliably, such as through a low-pressure and high-velocity metal injection or a high-pressure die-casting process. After casting, suitable alloys must maintain their properties sufficiently for the necessary application. Poor castability of the alloy often results in observed hot tearing, and can cause fill issues which typically decreases the mechanical and electrical properties of the end cast part.

Tesla says it has created a cast aluminium alloy comprised of nickel and aluminium that has a yield strength of at least 90MPa and electrical conductivity of at least 48% IACS, along with several other iterations of the alloy with various nickel and iron weight percentages. It also is claiming the method for producing the alloys, which includes forming the melt and casting it according to the T5 process.

Tesla CEO Elon Musk has said the auto maker is shifting to an aluminium casting design instead of stamped steel for the Model Y. This and the new casting machine are likely part of several manufacturing improvements to be made for this programme.

As an automaker, Tesla Motors is still working to produce vehicles in high volume. But, as a material and process developer, Tesla’s patent applications show that it understands what metalcasters know: That quality and productivity are equally demanding goals.