castings within the crash zone. To do this, the cast parts would have to match the properties of the surround- ing extrusions (265-295 MPa UTS, 175-205 MPa YS, > 12% elongation). Consistency of properties within the crash zone is critical in establishing a repeatable crash absorption mode, according to Philip Vais, Principal Engineer-Materials Research for Honda R&D America. Honda was able to achieve the
necessary properties and additional design requirements with ablation casting by partnering with Alotech Limited, Cleveland, Ohio. Ablation casting is a new technology invented by Alotech that combines the com- plete flexibility of traditional sand casting techniques with rapid cooling of the molten alloy through the use of a water-soluble binder. Te lower front body, upper front
body and rear body nodes, currently cast at the Honda of America Anna Engine Plant in Ohio, showcases Honda’s ability to take external technlogy and work collaboratively with Alotech to integrate ablation casting into existing manufacturing requirements (a real-world technology transfer). For this reason, Honda and Alotech have earned the 2015 AFS/ Metal Casting Design & Purchasing Casting of the Year Award for the Acura NSX space frame nodes. Te materials group at Honda
R&D America was aware of the abla- tion casting process for several years. It first heard about the process by word of mouth and a conference paper and was working with Alotech on develop- ing the ablation process for potential use on future cars. “Te properties of ablation cast parts would match the properties of
CASTING OF THE YEAR
Cast Component: Lower front body, upper front body and rear body nodes. Casting Supplier: Honda of America Anna Engine Plant. Material: A356.2 aluminum. Weight: 8.296 lb. (lower front node), 6.713 lbs. (upper front node), 15.909 lbs. (rear node). Dimensions: 24.173 x 9.173 x 3.819 in. (lower front node), 16.732 x 5.551 x 6.89 in. (upper front node), and 18.819 x 9.882 x 16.929 in. (rear node). Application: Honda Acura NSX supercar space frame. Converted From: Previous design concepts utilized castings, stampings and extrusion parts that were welded together.
• The use of ablation casting to achieve excellent properties allowed the cast nodes to be used within the critical crash zone of the frame, opening up additional design freedom that led to cost savings and improved performance.
• Through component consolidation, Honda reduced cost by cutting tooling investment. Additionally, the application of a casting in the space frame eliminated the need for MIG (metal inert gas) weld length on each side of the vehicle, thereby minimizing thermal distor- tion of the space frame during construction.
• The mechanical properties of the hollow node castings match the properties of the surrounding extrusions. To crush in the proper mode, certain areas of the node castings also match the wall thickness of the extrusions (3-4mm). The nodes also incorporate thick section bosses to rigidly mount to the front suspension arms.
22 | MODERN CASTING April 2015
the surrounding extrusion members of the space-frame structure, allowing them to be located in the crash zone,” Vais said.
As the NSX designers started their
second round of design work, they successfully increased the nodes’ size to consolidate several surrounding stampings and extrusions from the first-round design. To be located within the crash
zone, the castings must meet several important requirements: 1. The mechanical properties of the node castings must match the prop-
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