Low-Volume Vacuum Casting Services for Plastic Housings

One-Piece Home Appliance Bottom Housing in PC-Like PU

When a plastic housing is required in a small batch, production injection tooling may not always be the most economical choice. Vacuum casting services, also known as urethane casting, provide an alternative for producing multiple plastic parts from a reusable silicone mold.

For this home appliance project, the customer required a one-piece bottom housing with multiple openings, mounting areas, and integrated structural features.

A silicone mold was made from a carefully finished master pattern, followed by vacuum casting using a black PC-like polyurethane (PU) resin. One silicone mold could typically produce approximately 15–20 parts, helping spread the tooling cost across the required batch.

After casting, each housing was trimmed and deburred. The cosmetic surfaces were then sanded and painted black. The project required approximately ±0.1 mm dimensional accuracy for specified features.

The result was a practical low-volume manufacturing route for producing complete plastic housings without investing immediately in an injection mold.

Project Overview

Why Vacuum Casting for Low-Volume Plastic Parts?

The manufacturing strategy changes when a customer needs more than one or two prototypes but still does not require production quantities.

Instead of manufacturing every housing individually, vacuum casting uses a simple replication process:

Master Pattern → Silicone Mold → Repeated Casting → Finished Parts

Once the master has been completed, the silicone mold can be reused to produce multiple copies.

For this project, approximately 15–20 housings could typically be produced from one silicone mold, depending on part geometry, resin, mold condition, and demolding requirements.

This makes silicone tooling particularly useful for low-volume plastic parts, where the customer needs repeated components but does not yet want to invest in injection molding tooling.

One-Piece Casting for an Integrated Bottom Housing

The bottom housing incorporates multiple functional areas into one component, including openings, mounting locations, perimeter structures, and internal assembly features.

Producing the housing as one complete casting avoids additional bonding and assembly of separate prototype sections.

This helps reduce potential issues such as:

• Joint lines and adhesive marks
• Alignment differences between sections
• Additional assembly operations
• Dimensional stack-up
• Inconsistent mating areas

More importantly, the customer receives a complete housing that can be used directly for product assembly and evaluation.

PC-Like Polyurethane (PU) Resin

A PC-like polyurethane (PU) resin was selected for the vacuum casting process.

These polyurethane casting systems are formulated to simulate selected characteristics of engineering plastics such as polycarbonate.

For this project, the PC-like PU provided a useful combination of rigidity, toughness, structural stability, detail reproduction, and surface finishing capability.

PC-like PU should not be confused with injection-molded polycarbonate. If actual production-grade PC properties, specific certifications, or demanding thermal and mechanical performance are required, another manufacturing process may be more suitable.

The prototype material should always be selected according to how the finished parts will be used.

Dimensional Control for Assembly Features

The project required approximately ±0.1 mm accuracy for specified dimensions.

For a structural housing, inspection should focus particularly on features that influence assembly, such as:

• Mounting locations
• Functional openings
• Locating features
• Mating edges
• Assembly interfaces

The relationship between these features is also important. Even when individual details are correctly reproduced, excessive overall distortion can affect how the housing fits with other components.

Dimensional control therefore considers both critical local features and the complete one-piece structure.

Trimming, Deburring and Black Painting

Vacuum casting parts require post-processing after demolding.

For this housing, casting gates and flash were removed first. Edges, openings, and functional areas were then trimmed and deburred.

Because the product also had cosmetic requirements, the visible surfaces were carefully sanded before black painting.

The finishing sequence included:

Vacuum Casting → Trimming → Deburring → Inspection → Sanding → Black Painting → Final Check

Good surface preparation is particularly important for painted housings. Gate marks, scratches, parting lines, and uneven sanding can remain visible after coating if they are not properly treated beforehand.

From One Master to 15–20 Parts

The main advantage of vacuum casting in this project was low-volume replication.

Instead of repeatedly producing every housing from the beginning, one finished master was used to create a silicone mold capable of producing multiple PC-like PU parts.

This manufacturing model can help reduce the initial tooling investment for quantities that are too low for conventional injection molding.

Vacuum casting can therefore be considered for:

• Low-volume plastic housings
• Engineering samples
• Assembly units
• Product evaluation parts
• Customer demonstration units
• Bridge quantities before injection molding

The appropriate process still depends on part geometry, quantity, material requirements, tolerance, and intended use.

Looking for a Vacuum Casting Supplier for Low-Volume Plastic Parts?

YS Precision provides vacuum casting and urethane casting services for custom low-volume plastic components, including housings, covers, structural parts, and other engineered components.

Send us your 3D CAD files, quantity, material requirements, critical tolerances, color, and surface finish. We can review the project and recommend a suitable manufacturing approach based on the actual part requirements.

For low-volume plastic production, the goal is not simply to make another prototype—it is to find the right balance between tooling cost, part quantity, dimensional requirements, and finished quality.