Tuesday, January 6, 2015

Techy Tuesday - Radical Improvement in Aluminum Sheet Production

Aluminum giant Alcoa has announced a new way of producing aluminum sheet, called a Micromill.  The eye opener is that they claim that the process time from when they melt the alloy constituents until the sheet is done has been reduced from 20 days to 20 minutes.   Along the way, they get improvements in the sheet's characteristics: it's got 40% greater formability, and is 30% stronger.  Those improvements, while noteworthy, aren't in the same class as the 20 days to 20 minutes. 

In truth, it's a whole new way of making sheet and the times aren't exactly comparable.  In an old plant, the aluminum was cast into enormous ingots,  roughly 2 to 3 feet wide, 2 feet tall, and 20 feet long or longer.  The ingots took most of that 20 days to cool to a temperature that could be manipulated and rolled.  The Micromill pours the molten alloy, cools it in a thin layer and then rolls it into sheets.  The Micromill reduces the size of the factory required to produce the sheet.  Joe Butler, Alcoa Micromill plant manager, San Antonio Works, says a current aluminum mill "is usually contained within a quarter to a half mile, and we're doing it in about 150 ft."  Another benefit is the process offers better microstructure of the metal crystals as they cool.  All useful metal alloys are greatly influenced by the processing the alloy gets as well as the composition. 

Alcoa has released an interesting PR video on the process. 

The new process is primarily aimed at automobile sheet metals, replacing steel to save weight and meet the coming 2025 54.5 MPG CAFE standards the Obama administration mandated, but the technology allows them to alter the process to change the properties of the alloy coming off in a more fluid, seamless process.  The benchmark of formability has been the steels the auto industry is familiar with, and aluminum hasn't allowed that.  They claim this process yields aluminum sheet as formable as steel.  That means they'll be able to get the shapes they want to produce in aluminum and not just steel. 
Customer trials at Alcoa's pilot Micromill facility in San Antonio have already validated the material's characteristics, surface quality, and overall performance. Alcoa has also acquired a strategic development customer, and is now qualifying the new material for next-generation automotive platforms.  Looks like Ford's aluminum F-150 pickup is just the first of a new wave. 


  1. A very tiny disagreement: The twenty days were mostly meaningless since there was always ingots ready to go into the mill. The "cost" to the extent there is one is in the storage of cooling ingots and not production. However the 30% stronger is a big deal. There are different grades of aluminum and aluminum alloy that is quite strong but plain old aluminum is quite weak and prone to fatigue and simply failing under stress it was designed to take. Any improvement in strength is a big deal.

  2. Anon - thanks for the input on that. I gathered that storing ingots while they cooled was a big part of the 20 days.

  3. Howdy All,

    1. But doesn't aluminum burn at lower temps than steel(remember the Falklands, the British Navy and Exocets)?

    2. Another gubmint mandate(CAFE) that makes travel more dangerous.


  4. ML27 - right you are. CAFE standards have been in place for a lot of years, and I don't think there has ever been anything presented saying they made cars safer.

    The only thing that has helped cars get safer is the constant engineering improvements companies do on their own dime.