Complementary production of the Acura NSX’s bespoke, 75-degree, twin turbocharged V-6 engine takes place at the company’s nearby Anna, Ohio engine plant and is undertaken by a small group of master engine builders.

With trial production underway and serial production starting in April, Acura is revealing additional details of the innovative manufacturing processes at the PMC and Anna Engine Plant.

First 100% robotic MIG welding. the NSX’s aluminum-intensive space frame is constructed using advanced joining technologies. The multi-material space frame is created with 100% robotic Metal Inert Gas (MIG) welding, an automobile industry first. MIG welding uses an arc of electricity to create a short circuit between a continuously fed wire and the metal being welded. The heat produced by the short circuit, along with an inert gas locally melts the metal and allows them to mix together.

Developed in the 1940s, the MIG process has been semi-automated up to now, with a skilled human welder working with a MIG welding machine.

Eight weld robots apply 860 MIG welds to the space frame, ensuring highly precise and repeatable welds and a highly accurate body.

360-degree-rotating rotisserie-style body fixtures aid precision by turning the body during the process to provide optimal access for the robotic weld arms.

Weld technicians both visually inspect and take precise measurements of each part and at every stage of the welding process to validate the quality, precision and dimensional accuracy of the space frame, which is critical for both the dynamic performance of the vehicle and precise fitment of its powertrain, suspension, body panels and other components in assembly.

First automotive application of Ablation casting. The first application of ablation casting in the automotive industry is utilized for the creation of six nodes with the NSX space frame, serving as rigid suspension and powertrain mounting points and as critical elements of the vehicle’s crash structure. The ablation cast nodes are produced at the company’s Anna, Ohio engine plant, where its V-6 engine is also assembled.

Ablation casting, developed by Alotech, Ltd., combines the complete flexibility of traditional sand casting techniques with rapid cooling of the molten alloy through the use of a water-soluble binder. High cooling rates and control of solidification direction allows for exceptional mechanical properties and complex shapes.

In earlier design stages, Honda engineers had specified small cast aluminum joints in the space frame—but outside of the crash zones. They saw an opportunity for additional part consolidation and space frame performance if they could design the castings within the crash zone. This required casting parts with properties matching the surrounding extrusions (265-295 MPa UTS, 175-205 MPa YS, > 12% elongation).

The ablation casting process allows for the fine-tuning of both the cast part’s shape, as well as the material properties of the castings in the energy-absorbing areas of the vehicle, while minimizing weight in the form of a hollow part with optimized wall thickness.

Unlike traditional castings, the high-strength and ductile properties of the aluminum ablation cast members allow these sections of the space-frame to progressively crush and are designed to withstand tremendous loads of up to 210 kN without breaking.

Honda and Alotech won the 2015 AFS/Metal Casting Design & Purchasing Casting of the Year Award for the Acura NSX space frame nodes.

Hand built engine.: the NSX’s 3.5-liter twin-turbocharged V-6 engine with dry sump lubrication is hand assembled at the Anna Engine Plant. Each engine takes more than six hours to assemble. Each of 547 bolts is hand started and manually tightened to precise torque tolerances.

Each NSX engine is machine-balanced, bench-tested and broken-in to the equivalent of 150 miles of service to ensure that every NSX engine is track-ready upon customer delivery.

The engine build process was benchmarked against the company’s race engineering programs to ensure the highest possible quality and performance standards were achieved.

Space frame with zirconium pre-treatment. The aluminum-intensive NSX space frame undergoes an etching process prior to application of corrosion-resistant primer using a zirconium-based material. While instrumental for world-class quality, the use of zirconium also reduces environmental waste in the painting process.

Rotisserie-style sealer application. The use of two rotisseries in the body sealing application process—in which the space frame is loaded onto the fixture, elevated and rotated 360 degrees—provides for more precise application of sealer and improved ergonomics for technicians. The rotisserie is also employed in an industry first application in that it allows for one-sided attachment of the frame for more efficient loading and unloading and is a patent-pending design.

Dynamic performance confirmation. Drawing from the company’s race engineering expertise, the NSX undergoes a rigorous pre-delivery dynamic performance confirmation process that includes a detailed 45-minute wheel alignment process, four-corner weight and ride height check and precision measurements of brake performance at all four wheels, along with other critical performance quality checks. Half of the PMC’s 12 US patent applications relate to the unique processes created in this area.

Resources

• Prescenzi, A., (2015) "Cast Body Nodes for 2016 Acura NSX," SAE Int. J. Mater. Manf. 8(3):722-730 doi: 10.4271/2015-01-0512