A hot topic in electric vehicle (EV) manufacturing is “gigacasting”. This is where large stamped metal structural components are replaced with giant castings. The rationale is that this reduces weight and cost, two very important considerations for electric vehicles.

What gets overlooked in this discussion is that weight and cost reduction can also be achieved through greater use of investment casting. Furthermore, this proven process involves a lot of less capital investment and risk, and adoption lead times are far shorter. Here’s a look at the use of investment casting for EV components.

EV Industry Challenges

Batteries are heavy, which gives rise to all the charging and range anxiety concerns, and the vehicles are expensive, affecting sales and profitability. Tackling these challenges requires, in addition to developing better battery technologies, using higher strength-to-weight components, and reducing the amount of assembly work needed.

Investment casting answers both these challenges. To understand how, let’s take a look at the process.

Investment Casting for EV Components

The investment casting process can create parts with complex geometries, tight tolerances, and smooth surfaces. Almost any metal can be investment cast, although it’s especially effective for those with good fluidity, like aluminum, that flow readily into tight spaces.

Particular strengths are the ability to produce thin sections, and not needing draft angles to release the pattern or part from the mold. The high precision and good surface finish reduce secondary machining requirements.

Investment casting molds are expendable, meaning a new mold is needed for each part produced. Molds are made by coating a wax pattern with a ceramic slurry that dries to form a hard shell. The wax is then melted-out to leave the mold cavity.

For high quantity production, wax patterns are produced by injection molding. While this process imposes design limitations in terms of part ejection, multiple wax pieces can be assembled into larger and more complex patterns. When samples and prototypes are needed quickly, investment casting foundries are making increasing use of 3D printing to minimize lead times.

Maximum casting size and mass are limited by the pattern dipping process and the shell thickness needed to support the weight of metal poured. The upper size limits are generally an envelope of around 16″x12″x12″ and a weight of 30 lbs.

EV Components Suitable for Investment Casting

Examples of good candidates include:

• Heat sinks
• Housings
• Brackets
• Steering components
• Suspension members
• Battery components
• Door handles
• Seat frames

Benefits of Investment Casting EV Components

Investment casting helps EV manufacturers meet challenging weight reduction goals while simultaneously providing a way to reduce total manufacturing costs. These flow from the ability of the process to create complex, near-net-shape forms. This in turn enables weight reduction, component consolidation, and cost savings.

Mass is reduced by giving designers the freedom to put material only where it’s needed. Anything not contributing to strength and stiffness can be eliminated by casting holes or pockets.

Component consolidation reduces mass by eliminating unnecessary design elements. It can also reduce the use of fasteners, and eliminate the need for welding. The former contributes to weight reduction while both simplify assembly.

Eliminating fasteners and reducing the need for assembly and secondary machining also take cost out of downstream finishing and assembly operations.

Proven Investment Casting Capabilities

Gigacasting is an attractive concept, but the equipment and tooling is hugely expensive and process development lengthy and complex. Together, these act as counterweights to process adoption.

Investment casting can achieve the same goals, (subject to limits on size and weight), but is a proven process that uses existing manufacturing assets, knowledge and technology. Plus, with 3D printing, it’s possible to compress small quantity lead times to a matter of days.

Impro is a leader in the investment casting industry, and with IATF 16949 certification, supplies complex castings to automotive manufacturers. Contact us to learn more or request a quote.