Aluminum plays a crucial function in decreasing the weight of a vehicle and therefore also helps to minimise fuel consumption. A contemporary automobile includes enormous quantities of aluminium and consumption of the metal is on the rise, which is why aluminium component manufacture is on the rise.
It is so crucial to utilise the material as ideally as possible, and a new casting method developed in Norway has the ability to achieve precisely that. The technology is termed Low-Pressure Casting (LPC) and makes it feasible to cast aluminium bolts with high-quality surface qualities. This allows the metal to be utilised directly in the fabrication of elements such as suspension components in vehicles.
Streamlining manufacturing and saving on raw materials
Casting makes the manufacture of aluminium automotive components less costly, more eco-friendly, and more efficient. It also reduces the wasting of significant volumes of raw resources. The casting method has been developed by the aluminium company Hydro and is carried out under vacuum circumstances. In order to examine and show the possibilities of the technology, Hydro has asked SINTEF and Raufoss Technology to join forces as part of a project dubbed HyForge. So far, the findings have been quite positive.
“This casting method includes the elimination of an entire process step in the manufacturing line,” says SINTEF researcher Siri Marthe Arbo.
Currently, a vehicle component manufacturing line is made up of multiple phases, including casting, heat treatment, extrusion and the following forging/shaping process that guarantees that the finished product is fashioned with its desired form.
“Our technique essentially eliminates the extrusion step,” adds Arbo.
Savings on all fronts
Currently, it is usual for the industry to employ extruded bolts in the fabrication of suspension components. This is an expensive, time- and energy-consuming procedure that also creates significant amounts of ‘waste.
“The extrusion technique includes shoving the metal through a nozzle,” adds Arbo. “The purpose is to assure manufacture of a homogenous material that is free of impurities and surface imperfections. But it functions in the same manner as a toothpaste tube, so there is always some leftover waste,” she says.
The research team has utilised Hydro’s new casting technique to show that it is feasible to cast bolts used in suspension components and so remove the extrusion step from the manufacturing process.
“The new casting method results in fewer flaws and offers the raw material a high-quality surface finish,” adds Arbo. “This is a gamechanger in the fabrication of aluminium automotive components since the method is both faster and cheaper without the extrusion step,” she explains.
Stringent quality standards
The research team has been striving to develop a knowledge of how the cast material behaves and what qualities it obtains during forging. It has been performing comparisons to find ideal alloy compositions and looking at what improvements need to be made to the manufacturing process.
“Our emphasis has been on establishing a manufacturing process that assures that the suspension system has the appropriate qualities,” explains Arbo. “This is a safety-critical component, therefore there are severe standards when it comes to the quality and qualities of the product,” she explains.
“We’ve been looking at heat treatment and all the many phases in the process that the material needs to undergo so that we can show that the cast material is free of flaws and suitable for purpose. We’ve also been utilising models and simulations to assist us better understand what happens to the material throughout the manufacturing process,” explains Arbo.
In addition to laboratory testing, the team has carried out practical studies in partnership with the project’s industrial partner Raufoss Technology. These have required developing the first demonstration of a manufacturing line for aluminium suspension components utilising cast bolts.
A entirely Norwegian value chain?
The purpose of the HyForge project is to show, and develop trust in the fact, that the usage of cast bolts is the best means of making suspension components in the future. SINTEF is engaged in this research in partnership with Hydro and Raufoss Technology. The latter has for many years produced parts for the majority of brands of automobile, with a specialisation on aluminium components. It is absolutely feasible that the initiative may lead to a wholly Norwegian value chain that may increase wealth development in the nation.
“Our carbon footprint will be lowered even more if we acquire cast components from Hydro in Husnes instead of extruded bolts that have to be carried from central Europe,” explains Jørgen Li of Raufoss Technology. “Transport will also become simpler and more dependable,” he argues.
“Our objective has always been to replace extruded with cast bolts in our current manufacturing line at Raufoss where we produce components for Volvo,” adds Li.
Li demonstrates that a change from extruded to cast bolts provides the greatest opportunity for costs reductions associated to the Raufoss manufacturing process. It will also minimise the company’s carbon impact.
The study team has projected that it will be feasible to conserve as much as 39 kg of CO2 equivalents each automobile. Today, the entire emissions number for a vehicle is 98 kilos of CO2 equivalents, according to estimates provided by SINTEF. These statistics correspond for the most part to transit and, not least, to the fact that Norwegian aluminium is manufactured using “green” energy generated from hydropower.
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