How to design lightweight EV subframes, battery housings and enclosures

Electric vehicle design is defined by one overriding constraint, which is that every kilogram matters. EV range, performance and cost are all directly tied to vehicle mass. This has pushed engineers to rethink materials and architectures on top of the fundamentals of how EV structures are joined, serviced and maintained.

Subframes, battery housings and protective enclosures sit at the centre of this challenge. They need to be strong enough to protect high-value battery systems yet as light as possible to maximise range and efficiency. Achieving this balance increasingly depends on the intelligent use of lightweight materials, and just as importantly, on how those materials are fastened together.

Lightweight materials are reshaping EV structures

To reduce mass and improve efficiency, EV designers are turning to light alloys such as aluminium and magnesium and a range of advanced composites. Aluminium, in particular, offers a superior strength-to-weight ratio compared to steel and has become a cornerstone of EV structures from frames to battery housings.

Composite materials (including polymer matrix composites and hybrid combinations) are also gaining traction thanks to their combination of low density and high mechanical performance. These materials help designers push the boundaries of both weight reduction and design flexibility.

However, the very properties that make lightweight alloys and composites attractive also introduce challenges at the mechanical joint level.

Joint-level challenges in lightweight EV designs

Light alloys and composites are often softer and less wear-resistant than traditional steels. This can create issues in threaded connections where screws or bolts engage directly with the parent material. Common problems include:

• Thread stripping or deformation under torque

• Reduced fatigue resistance under vibration and thermal cycling

• Thread wear with repeated assembly/disassembly

These phenomena arise because softer materials provide less inherent resistance against localised stresses where the fastener engages, making them prone to early failure if not properly reinforced.

In EV subframes and battery housings, joints must withstand high clamp loads, temperature shifts, and sometimes repeated disassembly for inspection or repair. Without reinforcement, designers often have to compromise by increasing wall thickness or selecting heavier fasteners, both of which work against core lightweighting goals.

How wire thread inserts enable lightweight materials without compromise

Wire thread inserts fundamentally change how loads are transferred within a joint. Rather than allowing the fastener to bear directly against a soft parent material, the insert provides a hardened, wear-resistant threaded interface that distributes load evenly along the engagement length. In EV subframes, battery housings and enclosures, this delivers several critical benefits:

• Preserved joint strength in lightweight alloys and composites

• Improved resistance to thread wear and pull-out, even under high clamp loads

• More consistent torque-to-preload behaviour, improving joint reliability

• Longer service life for components designed to be disassembled and reused

Crucially, wire thread inserts allow engineers to maintain compact, lightweight designs without oversizing joints or reverting to heavier materials simply to protect threads.

Why tangless inserts are particularly well suited to EV manufacturing

While wire thread inserts in general address strength and durability challenges, Tangless inserts offer additional advantages that align closely with EV manufacturing and lifecycle requirements.

Unlike traditional tanged inserts, Tangless designs eliminate the need to break off and account for a tang after installation. While this may seem like a small change, it has meaningful implications for EV production and maintenance.

Simplified manufacturing processes

Removing the tang eliminates a manual step and the need for tang accounting, reducing process complexity and the risk of error in high-volume assembly environments.

FOD-free installation

With no tang to remove, there is no risk of loose debris inside battery enclosures or structural cavities, which is an important consideration for safety-critical EV systems.

Improved serviceability and disassembly

Tangless inserts are fully removable using dedicated tooling, allowing threads to be replaced or restored without damaging the parent material. This supports repair, refurbishment and long-term vehicle maintenance.

Bidirectional installation and removal

Tangless designs can be installed and extracted from either direction, which is particularly valuable in compact EV assemblies with limited access.

Designing lighter EV structures without compromising joints

Lightweight alloys and composites are transforming the design of EV subframes, battery housings and enclosures, but their success depends on how effectively joints are engineered to handle load, torque and repeated service in softer materials.

KATO Advanex’s Tangless® wire thread inserts are designed specifically to solve these challenges, reinforcing lightweight structures while preserving predictable torque performance and long-term durability. By removing the need for tang break-off, Tangless® inserts also simplify manufacturing, eliminate debris risk and support efficient disassembly and maintenance.

Drawing on decades of aerospace-proven expertise, KATO enables EV manufacturers to confidently design lighter, stronger and more serviceable structures without compromising manufacturing efficiency.