What is Vacuum casting of plastics?

Vacuum casting of plastics is a manufacturing technique used to produce plastic parts with high detail, precision, and surface quality by using silicone molds and thermosetting resins or polyurethanes. This process is commonly applied for functional prototypes, short production runs, or pre-series during the product development phase, where creating a metal injection mold is not yet economically viable.

The vacuum casting of plastics process begins by creating a flexible silicone mold from a master model, which is typically 3D printed or CNC machined. Once cured, the mold is placed in a vacuum chamber, where liquid plastic resin is poured into the cavity. The vacuum removes air bubbles and ensures the resin flows uniformly throughout the mold, capturing even the finest details of the original model.

After pouring, the resin cures in a low-temperature oven until solidified. The resulting part offers excellent dimensional fidelity and surface finishes comparable to injection-molded components. Depending on the chosen resin, parts can be transparent, colored, rigid, or flexible, and can even mimic properties of technical plastics such as ABS, PP, or elastomers.

One of the key advantages of vacuum casting of plastics is its speed and low tooling cost compared to steel or aluminum molds. It enables rapid design iterations, making it ideal for concept validation, functional testing, and client or investor presentations. It’s also suitable for producing end-use parts in small batches when tooling investment isn’t justified.

Another major benefit is the versatility of materials. Vacuum casting resins come in a variety of hardness levels, thermal resistance, UV stability, and compatibility with paints or surface coatings. This flexibility allows manufacturers to tailor part properties to specific project requirements—even in early development stages.

At Plásticos Lezo, while our core specialization is plastic injection molding, we collaborate with suppliers and technology partners who employ vacuum casting of plastics as part of the pre-industrialization process. This method helps us accelerate design validation before final mold production, conduct assembly trials, assess tolerances, and evaluate aesthetic or ergonomic aspects.

We also support clients needing final-use parts for specific applications that require fast, flexible, and high-quality solutions in low volumes. In such cases, vacuum casting proves to be an effective alternative to produce fully functional parts without compromising precision or performance.

In summary, vacuum casting of plastics is a complementary technology that provides agility, accuracy, and versatility during product development. Its ability to replicate complex details, adapt to various material needs, and reduce validation times makes it a strategic tool for prototyping, preproduction, or short-run manufacturing. At Plásticos Lezo, we incorporate it into our end-to-end solutions—from concept through to full-scale production.