Get the Heavy Iron out of Heavy Trucks

The upcoming Euro 7 regulations are reshaping how commercial vehicles are engineered, placing new demands not just on emissions control but on vehicle architecture, durability, and weight efficiency. For heavy-duty trucks, the norm demands stricter limits on NOx and particulate matter, along with requirements for extended component lifespans and tighter control of non-exhaust emissions such as brake dust and tire wear.

These changes ripple far beyond the powertrain. To absorb the added weight of the emission aftertreatment system, or in the case of electric trucks, the sheer mass of batteries, OEMs are under mounting pressure to reduce structural weight wherever possible. One clear opportunity lies in replacing traditional gray iron castings used in suspension arms, brackets, housings, and crossmembers.

This is where Rheocasting of aluminium alloys comes into play, offering a unique balance of strength, castability, and cost-effectiveness. Rheocasting enables the production of components with significantly lower weight compared to conventional sand- or die-cast parts. When applied to gray iron applications, helping OEMs and Tier-1 suppliers reclaim critical payload capacity lost to Euro 7-driven system complexity, especially in battery-electric trucks, where every kilogram reclaimed from the chassis directly improves range or cargo efficiency.

The Challenge of Euro 7 Payload

Euro 7 introduces stricter emission limits and system durability requirements than its predecessors. For internal combustion trucks, this means additional hardware: larger selective catalytic reduction (SCR) systems, double-dosing injectors, ammonia slip catalysts, particulate filters, and more onboard diagnostics. These add significant mass to the vehicle.

For electric trucks, the payload penalty is even more pronounced. Battery-electric powertrains can add over 2,000 kg to a heavy-duty truck, which not only impacts energy efficiency but directly reduces the vehicle’s freight-carrying capacity. While European regulations allow a 2-tonne gross vehicle weight compensation for zero-emission trucks, this is often insufficient to fully offset the weight of the battery systems.

Consequently, reducing structural weight has become essential. This makes the search for high-performance, lightweight replacements for gray iron castings all the more urgent.

Why Rheocasting?

Rheocasting offers distinct advantages over conventional casting when applied to aluminium alloys like A356. In the context of heavy trucks, these benefits translate into components that are not only lighter but also structurally robust enough to replace iron in fatigue-load applications such as axle carriers, crossmembers, suspension brackets, and transmission cases.

Gray iron has long been the material of choice for truck components requiring stiffness, vibration damping, and low cost. But its density (~7.2 g/cm³) is nearly three times that of A356 aluminium (~2.7 g/cm³). This opens up significant lightweighting potential. For example:

• A suspension bracket cast initially in gray iron at 12 kg could weigh as little as 4.5–5 kg when re-engineered in Rheocasting A356.

• A differential housing or carrier can shed tens of kilograms with no loss in functionality if optimised using Rheocasting.
  
  

In battery-electric trucks, where battery packs alone can weigh up to 5,000 kg, every gram reclaimed elsewhere in the vehicle architecture helps extend range or restore payload. Rheocasting A356 components are ideal candidates for structural and sub-structural elements in these applications, particularly because EVs eliminate the engine and transmission tunnel, enabling rethinking of load paths and component placement. Additionally, regenerative braking reduces loads on suspension and axle systems, allowing for the use of lighter materials in design.

Regulation as a Catalyst for Innovation

Euro 7 has created new design constraints, but also new opportunities. The demand for lighter, more efficient trucks, particularly electric ones, has pushed the industry to re-evaluate traditional materials and manufacturing methods. Rheocasting of A356 offers a compelling, production-ready solution to reduce structural mass, improve energy efficiency, and recover payload lost to emissions or battery systems.

By replacing gray iron with Rheocasting aluminium in strategic components, manufacturers can not only meet regulatory goals but also unlock competitive advantages in vehicle performance, range, and lifecycle cost.

Take this shift in vehicle design as an opportunity and incorporate these castings into your production. The Rheocasting Expert on Demand Consulting Service shows you how to do it from business development through to series production. Schedule a Free Consultation Call for more insights.