Polymer 3D Printing vs. Vacuum Casting

Which manufacturing method you choose makes all the difference in the outcome of your project.

However, knowing which method to use isn’t always obvious. Two techniques that stand out are 3D printing and vacuum casting. Each method offers distinctive strengths and advantages that are uniquely suited to a variety of situations.

In short, 3D printing brings a quick, flexible, and precise process tailored for prototyping and limited batch production; the casting process in vacuum casting offers a cost-effective solution that shines in high-quality, low to medium-volume production.

Let’s dive a little deeper into the pros and cons of each method.

The Manufacturing Process: 3D Printing vs. Vacuum Casting

There are many different 3D printing technologies for polymers, such as Fused Deposition Modeling, Multi Jet Fusion, and Stereolithography. The underlying technology, materials, and printing capabilities all vary between these manufacturing methods, but the process is generally the same.

First, a digital design is brought to life using CAD software. This design is then processed by slicing software which interprets it into layers for the 3D printer to follow. Next, the 3D printer creates the part layer by layer, following the prepared instructions. Finally, the part generally needs post-processing, including support removal, sanding, or painting.

The vacuum casting process relies on molds to create detailed parts.

First, a master pattern is created. The master pattern is encased in silicone, forming a silicone mold. Next, the mold is then filled with a material. The material fills the mold cavity, ensuring the final part takes on the precise shape and details of the master pattern. Once hardened, the mold is removed, revealing the cast part. The mold can be reused approximately 20 times before a new mold is needed.

Choosing the Best Fit 

Production Costs: Varies

3D printing is usually more cost-effective for small-volume production. As production volume increases, the cost per part decreases, making vacuum casting the more economical choice for larger batch production, even though the mold can only be used approximately 20 times before requiring a replacement.

Strength: Vacuum Casting

Both manufacturing technologies can produce strong parts, but 3D-printed parts may exhibit anisotropy. This means their strength can vary depending on the direction of applied force due to the layer-by-layer construction. On the other hand, vacuum casting uses two-component polyurethane resins, which can mimic a wide range of plastics and thus achieve different material properties and strength characteristics without suffering from anisotropy.

Tooling Costs: 3D Printing

3D printing sidesteps the need for expensive molds or tooling; all that’s required is a 3D model and a printer. Vacuum casting, however, involves the creation of silicone molds for each part. While these molds are less expensive than those used in other manufacturing processes, they constitute an initial upfront cost. In comparison, injection molding involves higher initial tooling costs but is more cost-effective for large-scale production.

Design Freedom: 3D Printing

3D printing creates intricate geometries that would be challenging, if impossible, to achieve with traditional manufacturing methods. Vacuum casting’s capacity to handle complexity is contingent on the master model. CNC machining also offers high precision and is often used to create master models for vacuum casting. While highly detailed parts are possible, the presence of very intricate features or undercuts can complicate the mold-making process.

Production Speed: Varies

Among various manufacturing techniques, 3D printing excels in speed for low-volume production and prototyping, often delivering a finished part within hours. Conversely, vacuum casting, although slower in process speed due to mold creation and curing, can be faster per part when factoring in batch production.

On the MakerVerse platform, you can expect lead times starting at six days for 3D printing technologies such as Fused Deposition Modeling. Vacuum casting lead times start at nine days, comparable to some of the other polymer 3D printing technologies.

Finishes: Vacuum Casting

This part made with stereolithography will require post-processing to remove the support structures – and possibly additional finishing depending on the application.

Vacuum casting replicates the surface of the master model in great detail, including textures and logos, often requiring less post-processing. Therefore, vacuum casting might be more suitable if a project prioritizes a superior, ready-to-use surface finish. While 3D printing, particularly with high-resolution techniques like Stereolithography (SLA), can produce detailed parts, it often exhibits layer lines requiring further post-processing for a smoother finish.

Getting Started with Vacuum Casting and 3D Printing

3D printing, with its speed, design versatility, and suitability for low-volume production, has carved a unique niche for rapid prototyping and personalized parts. In contrast, with its inherent strength and excellent surface finish, Vacuum Casting is a top choice for durable, high-quality parts in low to medium volumes. This makes vacuum casting particularly advantageous in the automotive sector, where high-quality, detailed parts are essential for both prototyping and small-scale manufacturing.

Are you embarking on a manufacturing journey and unsure which technology to choose? Contact us today to get started with 3D printing, vacuum casting, or any other manufacturing method. We are here to guide you every step of the way.