FEATURE MATERIALS IN DESIGN & PROTOTYPING Aluminium is increasingly


being used in the automotive industry to meet


‘lightweighting’ demands. The introduction of Hot Form Quench (HFQ)


technology, however, means OEMs will be


able to form deep-drawn and complex shapes from high and ultra-high-


strength aluminium. John Sellors, Impression Technologies, explains


W


ith the need to reduce vehicle weight and increase efficiency in order to reduce


emissions, increase range and improve performance, lightweighting has never been more important in the automotive industry. This has driven a sustained increase in the use of aluminium for components and vehicle structures. In fact according to research agency Ducker Worldwide, aluminium content in cars will increase by up to 30% over the coming decade. While the use of aluminium to reduce weight


is nothing new, there is a constant mission to improve its structural strength, integrity, consistency, durability and safety, and reduce cost. Manufacturers are also always looking to make aluminium easier to work with, through improved, lower-cost production processes using standard, widely available, alloys. Any new process must balance these factors and operate increasingly efficiently, while affording greater design possibilities. One highly innovative solution which offers a


step-change in lightweighting potential is Hot Form Quench (HFQ) technology. This easy-to- adopt process and forming simulation package allows OEMs to form deep-drawn and complex shapes from high and ultra-high strength


ALUMINIUM COMPONENTS Aluminium has already gained a foothold in vehicle construction, particularly with premium brands like Rolls-Royce, Jaguar Land Rover, Audi, Aston Martin and Tesla. Ford has also pioneered the use of high-volume aluminium- bodied vehicles with its F-150 pick-up truck. Aluminium is increasingly used in closures,


The first stage is to heat a standard heat-treatable grade of aluminium sheet in a furnace to its solutionising temperature of around 550˚C, depending on the grade of aluminium alloy


22 MARCH 2020 | DESIGN SOLUTIONS


bumpers, sub-frames, wheels, engine blocks and suspension components and, specifically in the premium segment, entire ‘body-in-white’ construction. Using aluminium for sheet product in body-in-white construction, within budgets, can also generate significant additional advantages for volume manufacturers. By utilising HFQ-designed parts, automotive manufacturers can use a variety of different aluminium grades, namely 6xxx and ultra- high-strength 7xxx series aluminium. In future, high recycled content alloys, offering lower cost and major carbon-saving benefits, will be compatible with the HFQ process which, because of its characteristics, can maintain formability even with high impurity levels, which would otherwise render the alloy unsuitable. Linked to its


aluminium, replacing steel or cold-formed aluminium grades. Being a rapid process, it meets the cycle times required for low-cost, high-volume, manufacturing. Encompassing simulation, design and


manufacturing of high-strength aluminium parts, HFQ aims to advance global standards of aluminium processing.


inherent recycling benefits, HFQ enables the creation of a closed-loop cycle of aluminium, as up to 90% of this metal could be recycled at the end of the product lifecycle.


THE HFQ PROCESS The first stage is to heat a standard heat- treatable grade of aluminium sheet in a furnace to its solutionising temperature of around 550˚C, depending on the grade of aluminium alloy. Via an automated process, the blank is


then transferred to a press and formed between a cold punch and die tool. The tools remain closed for five to 10 seconds to allow rapid cooling of the formed part, until the pressing is quenched. Quenching freezes the microstructure of the alloy in a supersaturated solid solution state. There is, in effect, virtually no cold-working of the aluminium alloy, eliminating the need for complicated springback compensation in part designs. Subsequently, should a heat-treatable


aluminium alloy be used, the part can be artificially aged to further increase its strength, thanks to the prior quenching method – taking a little over two hours for aluminium grade AA6082 to achieve peak strength. Partial artificial ageing may also be


undertaken, followed by full ageing after the part has been assembled into the vehicle structure. Full ageing in this scenario means HFQ pressing can take advantage of the heat generated during the paint bake process to achieve optimum strength. HFQ’s ability to improve formability widens


the scope for automotive applications in terms of design freedom, process optimisation and achieving high levels of structural strength and stiffness within component Bill of Materials (BOM) cost budgets.


GREATER FREEDOM OF DESIGN There are many advantages to be seen when HFQ forming is adopted at the outset of a design programme. Through HFQ, there is an opportunity to catalyse the greater adoption of high-strength aluminium alloys, allowing manufacturers to enhance and refine existing structures, while facilitating greater freedom in design and creation of new body and chassis concepts.


Impression Technologies https://impression-technologies.com/


/ DESIGNSOLUTIONS


HFQ: the key to vehicle ‘lightweighting’?


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