Lotus Engineering, a division of Group Lotus, Ltd., has changed the suspension uprights on its Elise sports car from aluminium to steel, saving the company £130 (about $US190) per vehicle, a 64 percent cost saving compared to the original upright design, reports the American Iron and Steel Institute.
The steel uprights also demonstrate significant performance improvements, compared to the previous aluminium design, with a weight increase of less than 3.5 pounds.
In making this change, the AISI claims, Lotus has successfully validated the claims of the UltraLight Steel Auto Suspension (ULSAS) study released in 2000, which showed how steel suspensions can reduce mass, lower cost and improve performance, of traditional steel-based suspension systems.
In a soon to be released report, Lotus attributes the performance gains, including greater stiffness and durability than the displaced aluminium design, to the new high-technology steels available to automotive designers today.
The Elise suspension upright design uses Air-Cooled Forged Steels (ACFSs). Lotus determined ACFSs were the optimal steel grade because of their hardness consistency from case to core (outer edge to centre) and ease of machining compared to other forged steel grades.
The benefits of ACFS include their greater durability under cyclic loads and the elimination of supplemental heat treating and annealing.
“We are pleased to see automakers applying ULSAS technology to optimise steel automotive suspension components,” said the director, Bar and Rod Programs for the American Iron and Steel Institute (AISI), David Anderson.
“Lotus has taken the lead to show the entire industry that ULSAS materials and technology can save OEMs money and improve performance, while making use of steel’s ‘recyclability’.”
The ULSAS project was undertaken by the global steel industry to demonstrate the effective use of steel in producing lightweight, structurally efficient and cost-effective steel automotive suspensions.