Vacuum Casting Complex Automotive Structural Parts

Nylon-Like PU Casting for Irregular, Multi-Feature Automotive Components

Automotive structural components often combine more geometry than their overall size suggests. Curved surfaces, ribs, raised sections, recessed areas, mounting features, and changes in section height can all be integrated into a single part.

For this project, the customer required approximately 20 black automotive structural parts. The component had a long, irregular profile with multiple curved transitions and features extending in different directions.

Producing every part by CNC machining would have required repeated setups and more complicated tool access. Instead, we manufactured a master pattern and used silicone mold vacuum casting with nylon-like polyurethane (PU) to reproduce the complete structure.

One silicone mold could typically produce approximately 20 parts, making this a practical low-volume manufacturing solution for the customer's required quantity.

Project Details

A Structural Part with More Than Simple Curves

The manufacturing challenge of this component came from the combination of features within one continuous structure.

The part includes a long irregular body together with:

• Curved and changing surface profiles
• Raised and recessed sections
• Local ribs and supporting features
• Small projections and mounting structures
• Features facing different directions
• Narrow transitions between structural areas

These characteristics make the part different from a conventional box-shaped housing or flat plastic cover.

When CNC machining is used, some features may require additional orientations, fixtures, or tool approaches. For a batch of approximately 20 identical components, the same manufacturing complexity is repeated for every part.

Vacuum casting provided a different way to approach the geometry.

Capture the Geometry Once, Then Replicate It

For this project, the complex geometry was first established in the master pattern.

A silicone mold was then created around the finished master, capturing the curved surfaces, local projections, ribs, transitions, and other structural details.

The production logic became:

Complex Master → Silicone Mold → Nylon-Like PU → Repeated Structural Parts

Once the geometry was transferred into the silicone tooling, the same complex form could be reproduced repeatedly without machining every feature from solid stock for each individual part.

For low-volume parts with irregular geometry, this replication approach can offer a meaningful cost advantage.

One-Piece Casting for Multi-Directional Features

One important benefit of silicone tooling is its flexibility during demolding.

For suitable geometries, this can allow features with different orientations and local undercuts to be incorporated into a single cast component.

That was particularly useful for this automotive structural part.

Producing the component as one piece avoided dividing the design into multiple simpler sections and joining them afterward.

This helps reduce:

• Bonding joints
• Additional assembly work
• Alignment variation
• Joint-related dimensional stack-up
• Visible connection areas

The result is a more integrated structural component for subsequent customer evaluation and assembly.

Nylon-Like PU for Structural Prototype Parts

A nylon-like polyurethane (PU) casting resin was selected according to the customer's material requirement.

Nylon-like PU can provide a useful balance of toughness, impact resistance, moderate flexibility, and structural strength, while also reproducing complex molded details.

This makes it suitable for certain automotive structural prototypes and low-volume components where the customer needs more functional behavior than a purely cosmetic model.

Nylon-like PU is not identical to production PA6 or PA66. Where testing depends on exact production nylon properties, temperature resistance, or specified automotive material standards, the final manufacturing material should be evaluated separately.

Why Quantity and Geometry Need to Be Considered Together

Low quantity alone does not automatically make vacuum casting the best process.

The geometry matters just as much.

A simple 20-piece plastic component may still be economical to CNC machine. But when those 20 parts contain complex curves, multiple feature directions, irregular transitions, and difficult tool-access areas, repeated machining becomes a larger part of the total cost.

For this project, one silicone mold could typically support approximately 20 castings.

Instead of repeating complex machining operations across the entire batch, the customer could invest in the master and silicone tooling once and then replicate the parts.

That is where the cost advantage came from.

Low-Volume Urethane Casting for Automotive Parts

This project demonstrates a useful application of vacuum casting and urethane casting for complex automotive structural components.

The manufacturing strategy was driven by:

Irregular Geometry + Multi-Directional Features + One-Piece Construction + Nylon-Like PU + Approx. 20 Parts

YS Precision supports low-volume vacuum casting for custom automotive structural parts and other complex plastic components.

Send us your 3D CAD files, required quantity, material requirements, critical dimensions, and intended application. We can review the geometry and evaluate whether vacuum casting, CNC machining, or another manufacturing process is the better fit.