Vacuum Casting Prototyping

What is Vacuum Casting Prototyping?

Vacuum Casting Rapid Prototyping is a technique used to rapidly prototype small quantities of products. The main steps include creating a master model, making a silicone mold, injecting resin into the mold using vacuum pressure, and curing the mold under the right conditions.This technique is suitable for applications that require rapid verification of design concepts and functionality, and is often used for engineering prototyping and pre-verification of small-volume production due to its lower cost and shorter production cycle. Vacuum casting rapid prototyping's ability to accurately replicate complex geometries and details while offering a wide range of material choices has led to a wide range of applications across multiple industries, such as automotive, consumer products, medical devices, and More.

Working Principle

Make the master model: First, the master model to be replicated is made according to the design requirements, usually the master model can be made by 3D printing, CNC Machining or by hand.

Making the silicone mold: The master model is placed in a container and then the master model is wrapped in liquid silicone to ensure that every detail of the surface of the master model is covered. Silicone is very flexible and adhesive and can accurately replicate the shape and details of the master model.

Vacuum Extraction: The container is sealed and the air inside the container is extracted by a vacuum pump to create a negative pressure environment. This step, called vacuum pumping, is designed to completely fit the silicone to the surface of the master model and remove all air bubbles.

RESIN INJECTION: When the silicone mold is ready, liquid resin is injected into the silicone mold by either injection or pouring. In some cases, the mold can be placed in a vacuum chamber prior to injection to further enhance the filling properties of the material.

Curing to shape: After the resin is injected, the silicone mold is cured under appropriate environmental conditions (e.g., room temperature or heat). This process usually takes a certain amount of time to ensure that the resin is fully cured for molding.

Mold Unmolding: When the resin is fully cured, the silicone mold can be easily detached from the master model. This results in a resin replica of the same shape as the master mold.

The key to vacuum casting rapid prototyping is the ability to produce high quality prototypes and small batches in a relatively short period of time by utilizing the high flexibility and precise replication capabilities of silicone molds, which are suitable for a wide range of applications requiring rapid verification.

Main Materials

Silicone Rubber :

Uses: Used to make molds that accurately replicate the details and surface texture of the master model.

Characteristics: Excellent flexibility and elasticity, able to withstand high temperatures and chemicals, high durability.

Advantages: Silicone molds can be used many times and can be completely fitted to the surface of the master model in a vacuum environment, ensuring the accuracy and quality of the replica.

Resin :

Uses: Used as a filler material for vacuum casting, injected into silicone molds to form final product prototypes or parts.

Characteristics: There are many different types of resins, commonly polyurethane, epoxy, and acrylic, each with different hardness, abrasion resistance, chemical resistance, and color options.

Advantages: The appropriate resin can be selected according to the requirements of the product, e.g. choose flexible polyurethane resins for applications requiring high elasticity, and epoxy resins for those requiring high strength and durability.

Additives and Pigments:

Uses: Used to adjust the hardness, color and specific physical properties of resins.

Characteristics: UV stabilizers can be added to improve weather resistance, and pigments are used to adjust the color and appearance of the product.

Advantages: Additives and pigments make the final product more in line with the design requirements and can meet the needs of different industries and applications.

By choosing the right type of silicone and resin and additives, vacuum casting offers a wide range of material choices and flexibility to adapt to different product design and application requirements, making it an ideal option for rapid prototyping and small batch production.

Application Areas

Vacuum casting rapid prototyping technology has demonstrated its wide range of applications and importance in several areas. Firstly, it plays a key role in the product development process by producing engineering prototypes and validation samples to help design teams evaluate the appearance, functionality and performance of their products. Second, vacuum casting is widely used in marketing and display modeling, providing an efficient and accurate means for companies to demonstrate the details and features of their products. In addition, the technology supports low-volume production, enabling rapid response to market demands and customization, especially in industries such as automotive, aerospace, medical devices, and consumer electronics.

Vacuum casting rapid prototyping has the following significant features and comparative advantages over other major rapid prototyping methods such as 3D printing, CNC machining and Injection Molding:

Accuracy and surface quality：

   - Vacuum casting is capable of accurately preserving the detail and surface quality of the prototype during the replication process, and typically has a higher surface finish and detail retention than most 3D printing technologies.

Material selection and performance:

   - Vacuum casting allows for the use of a wide range of resin materials, including polyurethanes and epoxies with different hardnesses, colors, and properties, making it more flexible in meeting the needs of specific applications.

Mass production and cost-effectiveness:

   - Although vacuum casting is typically used for small batch production, the cost of making tools and the shorter manufacturing lead time compared to traditional injection molding makes initial production costs lower and suitable for rapid validation and market testing.

Complex geometry handling:

   - Vacuum casting is capable of handling complex geometries and fine structures, which is beyond the reach of 3D printing technology in some cases, especially for parts and products that require high precision and complex designs.

Manufacturing efficiency and post-processing:

   - Vacuum casting typically requires fewer post-processes, such as surface treatments and adjustments, enabling faster generation of finished products and reducing the need for additional processes compared to 3D printing technology.

In summary, vacuum casting rapid prototyping makes it an important option for product development, small-volume production, and marketing through its advantages of high precision, diverse material options, adaptability to complex geometries, and cost-effectiveness. Compared with other rapid prototyping technologies, vacuum casting can provide superior manufacturing Solutions in specific scenarios, driving innovation and progress in the manufacturing industry.

In the vacuum casting rapid prototyping process, quality control and surface preparation are critical steps in ensuring the quality and appearance of the final product. Quality control includes ensuring that the silicone mold fits the master model perfectly, controlling the resin injection process, and accurately controlling curing and cooling conditions. The surface preparation stage covers demolding and thorough cleaning, as well as surface dressing and painting where necessary, to ensure that the product meets the requirements for high precision, finish and consistency. These measures not only improve the overall quality of the product, but also ensure its perfect visual and functional performance to meet the high requirements and expectations of our customers.