Mega casting technology not only cuts vehicle production costs for automakers but also will save consumers, and their insurers, money on vehicle repairs.
That’s the finding of a two-year study on crash testing and damage assessment by U.K. automotive technology testing specialist Thatcham Research.
The company’s team of specialists found the technology, currently employed by U.S. battery-electric-vehicle maker Tesla and being investigated by the likes of Toyota, Volkswagen, Volvo and Hyundai, can significantly reduce the cost of repairs and possibly even cut the number of vehicle write-offs for insurance companies.
In an exclusive interview with WardsAuto, Thatcham executives spell out the advantages of repairing mega cast aluminum sections versus the traditional multi-panel construction currently used by most automakers.
The biggest advantage that mega casting can bring to vehicle repairs is if sections are designed with potential repair work in mind right from the drawing board, says Richard Billyeald, Thatcham’s chief research and operations officer.
“The fact that you can section the vulnerable bits of the casting – and Tesla has a specific repair item that wedges in and bolts through, to address the issue of one large unit – that’s the sort of stuff that really makes a difference,” Billyeald tells WardsAuto.
The study was carried out following concerns raised by insurance companies over the potential cost of repairing the large, single-piece aluminum castings after a rear-end collision, one of the most prevalent no-fault collisions suffered by motorists today.
Thatcham’s research was conducted with real-world claims data from U.K. insurers and Allianz Centre for Technology (AZT) Germany.
Exhaustive crash testing was conducted at Thatcham’s headquarters in Berkshire, southern England, and concentrated on several Tesla Model Y vehicles, which feature a single-piece, aluminum rear floor section.
The model’s one-piece, mega cast rear chassis section consolidates a host of individual components into a single aluminum casting to reduce manufacturing time, cost and environmental impact.
Analysis of repair procedures claims the technology can reduce repair costs in both partial and full replacement scenarios when compared to conventional steel, multi-piece vehicle structures.
Repair work on the Model Ys is said to deliver consistent cost advantages including partial replacements resulting in a £2,167 ($2,932) saving over similar repairs on a Tesla Model 3 with its traditional multi-part steel rear sub-assembly construction, while even full replacements saved £519 ($702).
Similar patterns emerged when comparing against other manufacturers’ vehicles, with the Model Y demonstrating lower repair costs than other models, including the Mercedes EQE, Hyundai Ioniq 5 and several internal-combustion-engine vehicles.
An in-depth look at the testing shows that in low-severity testing at 15 km/h (9.3 mph), the mega cast exceeded expectations by sustaining no structural damage, allowing complete vehicle repair without any work required on the mega cast component itself.
Medium-severity testing at 25 km/h (15.5 mph) necessitated full mega cast replacement owing to crack propagation and structural misalignment.
However, at £716 ($969) for the replacement of the whole component, the total repair cost remained competitive with, and often below, traditional repair methods for equivalent damage.
These findings challenge initial industry concerns about the vulnerability of large single-piece castings to minor impacts, says Billyeald.
“What Tesla has come up with is to section these areas and then the repair parts can be bolted and glued so you are not having to work the aluminum sections and the repair process becomes all mechanical, making it much more manageable,” he explains.
Key Considerations
However, the research did highlight key considerations, including the fact that repairs requiring welding of the aluminum mega cast structure must be conducted at Tesla-approved facilities, raising questions about repair network capability as the technology becomes widespread.
This requirement could necessitate vehicle transportation between repair centers if the initial facility lacks appropriate certification, potentially adding time and expense to the repair process. Additionally, the scale and irregular shape of these mega cast components present handling challenges for smaller body shops.
Thatcham’s research team found many of the benefits for repairing a mega casting component come from the lack of complexity compared to traditional car-building techniques, says the company’s principal engineer for automotive repair, Darren Bright.
“I think the layering of the panels are key,” he tells WardsAuto. “If you imagine 90 separate panels made of aluminum held together with rivets and adhesive, the amount of trial fitments, dry-run fitments that you have to do to fit these panels together, lining everything up, press the holes for the rivets.
“Then you multiply that by how many separate joints you have, (and) there are a lot of potential points of failure in repair, such as putting a hole in the incorrect place – the worst thing you can do!”
Bright says Tesla’s use of replaceable cast rear rail assemblies, at just £31 ($42) each, covers most minor impacts.
He also points out that the Tesla mega cast unit is put together with two long welded joints whereas most other aluminum-bodied vehicles are riveted.
“So, on the Tesla, you can drill the welds out with a couple of additional bolted fixings… and then you are just putting rivets back. Really, quite a simple process,” he explains.
Billyeald stresses that the main driver for automakers to employ mega casting is to reduce production costs and that a badly designed unit will not perform as well as a traditional multi-piece component in the event of a collision.
“The real lesson here for carmakers and insurers is when the repairability has been considered at the design stage and methods and strategies for repair are implemented as part of that, you get a good result,” he says, adding: “It’s the thing that Tesla has done well.”
