In an article published in the Journal of Manufacturing Processes, researchers at the Pacific Northwest National Laboratory (PNNL) report their novel Shear Assisted Processing and Extrusion (ShAPE) technology (earlier post) 7075 aluminum alloy tubes at speeds of up to Can extrude 12.2 m / m. min without surface crack. This is the first experimental evidence of the high speed extrusion of 7075, which improves on traditional extrusion where 2.0 m / min is the limit.
While automakers are increasingly using aluminum in high-volume models to reduce vehicle weight – particularly Ford, which began building the F-150 with mostly aluminum bodies in 2014 – even more weight could be saved by using more advanced aluminum alloys for components such as roof rails, cross members, subframes and other structural parts. However, these alloys are expensive in part because of their slow production speeds using conventional extrusion.
The aluminum alloy 7075 has an 85% higher strength-to-weight ratio than the alloys found in typical passenger cars; however, the manufacturing costs are about 30% higher compared to the commonly used 6000 series alloys.
This price differential is acceptable in aerospace applications where lighter materials trump higher costs for better fuel efficiency, improved maneuverability and lower take-off costs. For vehicles, however, this is a limiting factor that we hopefully can change.
This high cost is mainly due to the fact that alloy 7075 is notoriously difficult to extrude into structural components. 7075 is widely considered to be the most difficult to extrude of all commercial aluminum alloys. The slow extrusion speed of only 1 to 2 meters per minute combined with higher energy requirements makes 7075 more expensive than the 6000 series alloys, which are extruded at more than 20 meters (65 feet) per minute.
The ShAPE- PNNL’s process uses a machine to spin billets or pieces of solid metal alloy using just enough heat from friction to soften the material so that it can easily be extruded through a die to form tubes, rods and channels . The simultaneous linear and rotational forces only consume 10% of the force normally required to push the material through the die using conventional methods.
This significant reduction in force enables significantly smaller production machines and thus lowers investment and operating costs. The energy consumption is similarly low. The amount of electricity used to make a 1 foot long pipe 2 inches in diameter is roughly the same as running a household kitchen stove for just 60 seconds.
The process results in a material with microstructure grains that are much finer than the grains of the material prior to extrusion. These finer grains and their orientation are typically uniform throughout the product and provide greater strength and ductility. For example, room temperature ductility in excess of 25% was independently measured, which is a great improvement over typical extrusions. Initial studies show that the process also greatly improves the energy absorption of the metal.
ShAPE can extrude tubes, wires and rods with strength properties that meet key industrial ASTM standards and typical ASM values. The elongation of Alloy 7075 is 50% higher than that of conventional extrusion, which can support energy absorption during a crash.
The ShAPE process can not only increase the speed, but also the energy-intensive thermal treatment steps that are involved in conventional extrusion are required, thereby saving about 50% of the energy required to extrude the 7075 alloy.
In conventional extrusion, the large metal bars must first be heat treated for about a day at temperatures of over 400 ° C (750 ° F) in order to homogenize or evenly distribute various elements such as magnesium and copper in the alloy. ShAPE is able to extrude billets without homogenization, saving an estimated 5% of the total cost of ShAPE extruded products.
Also, conventional extrusion requires preheating in an oven to soften the billet prior to extrusion. With ShAPE, no preheating is required as all the heat required comes from the process itself. Other thermal treatments after extrusion are also eliminated or reduced, resulting in a total energy saving of 50%.
The increased extrusion speed of ShAPE in combination with reduced energy consumption and thus lower CO2 emissions can make the lightweight 7075 alloy for make the car market cost-effective. Lighter vehicles ultimately also contribute to lower CO2 emissions in the transport sector by increasing the fuel efficiency of cars with internal combustion engines and longer distances per charge for electric cars.
Scott Whalen, Matthew Olszta, Md. Reza-E-Rabby, Timothy Roosendaal, Tianhao Wang, Darrell Herling, Brandon Scott Taysom, Sarah Suffield, Nicole Overman (2021) (ShAPE), “Journal of Manufacturing Processes, Volume 71, Pages 699-710, doi: 10.1016 / j.jmapro.2021.10.003.
Posted on October 27th, 2021 in Manufacturing, Market Background, Materials, Weight Loss | Permanent link
Sounds good – lighter and stronger and cheaper (!)
Let’s hope they can get it out or it’s just an interesting piece of paper.
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– New extrusion process for stronger aluminum alloys and accelerated vehicle production
– PNNL& # 39; s SHAPE enables high speed extrusion of 7075 aluminum alloy, improves some Material properties
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