Vacuum Casting Services

Vacuum casting is a versatile and efficient process used primarily for producing high-quality prototypes and small to medium production runs. Here’s a straightforward breakdown of how it operates:

Master Pattern Creation: The process begins with the production of a master pattern, typically made using a high-resolution 3D printer. This pattern is precisely crafted to represent the final part in detail.

Mold Making: A silicone mold is then created around the master pattern. The mold is made under vacuum conditions to ensure there are no air bubbles that could impact the mold’s accuracy and surface quality.

Casting: Once the mold is cured and the master pattern removed, the casting resin, often polyurethane, is mixed and poured into the mold. Vacuum is applied during the pouring process to avoid air entrapment and ensure a bubble-free casting, which replicates the master pattern with high fidelity.

Curing and Part Removal: The resin is allowed to cure within the mold. After curing, the part is removed from the mold, which can typically be reused to produce multiple copies.

Finishing Touches: The final step involves cleaning and finishing the cast parts to achieve the desired surface texture and detail, and applying any necessary paint or coating.

Vacuum casting and 3D printing are both valuable in the rapid prototyping stage, but urethane casting often holds distinct advantages, particularly for specific project requirements:

Material Properties: Vacuum casting uses materials that closely mimic those used in injection molding, providing parts with superior mechanical properties such as strength, flexibility, and heat resistance. This is particularly important for functional testing and end-use applications.

Surface Finish: Cast urethane parts generally have smoother and more refined surfaces compared to those produced by 3D printing, which can show layer lines and require additional post-processing for a smooth finish.

Color and Texture Options: Vacuum casting allows for a broader range of colors and textures without the need for post-processing. The versatility in finishing options directly from the mold is greater than in most 3D printing processes.

Production of Larger Quantities: While 3D printing is optimal for one-off prototypes or very small series, vacuum casting is more cost-effective and efficient when producing small to medium batches of parts, as the silicone molds can be used to make multiple copies from the same master model.

Durability: Urethane cast parts tend to be more durable and better suited for functional testing and consumer use, as the materials used can withstand more rigorous conditions.

Polyurethane vacuum casting offers several benefits compared to traditional injection molding, especially when it comes to prototyping and small production runs:

Lower Costs: Vacuum casting requires significantly lower upfront investment for tooling because it uses silicone molds, which are cheaper and faster to produce than the steel or aluminum molds needed for injection molding.

Faster Turnaround: Producing molds for vacuum casting takes considerably less time, allowing for a quicker turnaround from design to finished parts. This speed is crucial in projects with tight deadlines or where rapid iteration is needed.

Flexibility in Materials: While injection molding typically necessitates the use of thermoplastics, vacuum casting allows for a broader selection of materials, including various types of polyurethane resins that can mimic the properties of thermoplastics, elastomers, and rubbers.

High-Quality Detail and Finish: Vacuum casting can achieve excellent surface details and finish similar to injection molded parts. It is particularly effective for complex shapes and fine details that require high aesthetic qualities without the need for post-processing.

Color and Texture Customization: Polyurethane resins used in vacuum casting can be easily colored during the mixing process, allowing for integrated color and texture that can be tailored to specific design requirements without additional painting or finishing.

Ideal for Small Batches: Vacuum casting is cost-effective for small to medium batch production, providing a practical solution for quantities that are not large enough to justify the high costs of injection mold tooling.

When designing parts for vacuum casting, several key considerations can impact the success and efficiency of the production process:

Wall Thickness: Consistent wall thickness is crucial in vacuum casting to prevent warping and ensure uniform curing of the resin. Recommended wall thickness typically ranges from 1.5 to 5 mm, depending on the size and complexity of the part.

Draft Angles: Incorporating draft angles into the design helps in the easy removal of the part from the mold. A minimum draft angle of 1 to 2 degrees is advisable for most surfaces.

Undercuts and Overhangs: Designing with undercuts and overhangs needs careful planning as they can complicate the mold and increase costs. Using side-action cores or split molds can be solutions but will add to the complexity.

Ribs and Gussets: Adding ribs and gussets can enhance the strength and rigidity of the parts without significantly increasing the material volume and weight. Position them strategically to support structural integrity.

Venting and Gates: Proper placement of vents and gates is essential for ensuring air-free filling of the mold and complete resin flow to all parts of the mold. This prevents voids and ensures the quality of the final cast.

Surface Finish: The quality of the master model’s surface will directly impact the final part. Any texture or polish on the master model will be replicated in the casting.

To get a vacuum casting quote from RapidDirect, simply visit our website and use the online quoting platform. Start by uploading your CAD files directly into the system, which supports step, stp, igs, iges, prt, sldprt, sat, x_t, file formats for your convenience. After uploading, select the required details about your project like material type, finish, shipping options and quantity. Our project engineers will analyze your design for manufacturability and provide feedback, allowing you to make necessary adjustments. Once your design and specifications are finalized, you’ll get an accurate calculation of the cost and the estimated lead time. (Our platform doesn’t currently  support instant quote for vacuum casting). If the quote meets your requirements, you can confirm your order directly through the platform, and we will begin the production process according to your specifications. This streamlined online system ensures a quick and easy way to receive a precise quote and start your vacuum casting project with RapidDirect.

In vacuum casting, the mold, typically made from silicone, must be securely held together to ensure accurate and quality part production. This is achieved using a two-part mold system that encloses the liquid polyurethane resin during the casting process.

To hold the mold together, a rigid frame or box, often referred to as a mold case, is used. This case is usually constructed from materials such as aluminum or a robust plastic. It serves several critical functions: it supports the mold to maintain its shape and integrity under vacuum conditions, prevents the mold from bulging or deforming when the resin is poured, and ensures that the two halves of the mold align precisely without shifting.

Before the casting begins, the silicone mold is placed inside this rigid frame. The two halves of the mold are then tightly clamped or bolted together to prevent any leakage of the resin. This clamping also helps in creating a vacuum seal around the mold, which is essential for the vacuum casting process to work effectively. The vacuum helps to draw the resin into even the finest details of the mold, ensuring high-quality, detailed parts with minimal air bubbles or defects.