How does vacuum casting work?

With the continuous advancement of industrial technology, vacuum casting, as a high-precision, low-cost manufacturing process, has gradually occupied an important position in small-batch production and customization of complex parts. Especially in the fields of aerospace, automobiles, electronics and medicine, vacuum casting has become the preferred method for many high-end product prototypes and small-batch production due to its excellent detail performance and excellent physical properties.

Working principle of vacuum casting

The core principle of vacuum casting is to pour liquid materials (usually polyurethane resin, silicone rubber or metal) into a mold with negative pressure under a vacuum environment so that it solidifies under low pressure. This process effectively reduces the generation of bubbles and ensures that the surface of the casting is smooth and defect-free.

Vacuum casting workflow

Model making

Vacuum casting first requires the creation of an accurate prototype model, usually made by 3D printing or CNC machining. This stage is crucial because it directly determines the accuracy and appearance of the final product.

Mold making

Using a model to make a mold is a key step in vacuum casting. Common mold materials are silicone and polyurethane rubber, which can capture all the details of the prototype and are flexible enough for easy demolding. The mold is usually formed by pouring liquid silicone or other materials into the outside of the model and solidifying them over a certain period.

Pouring liquid materials

After the mold is ready, the factory will pour liquid resin (such as polyurethane resin) or other casting materials into the mold. In a vacuum environment, the liquid material enters every tiny part of the mold with the help of negative pressure, thereby reducing the generation of bubbles and ensuring the density and smoothness of the casting.

Curing and demoulding

After the coating is cured, the casting will be removed from the mold and further post-processed. It usually needs to be processed by grinding, polishing, spraying, etc. to ensure that it meets the customer's quality standards.

Post-processing

Depending on the customer's needs, the final casting may also require CNC processing, painting, marking and other subsequent processes to ensure that the appearance and function of the final product meet expectations.

Kaierwo vacuum casting parts manufacturing

Kaierwo produced a new medical device in small batches for a pharmaceutical company for market verification. For this short-term small batch production, vacuum casting is the most economical and rapid processing method. Kaierwo uses ABS plastic and PC plastic to manufacture this device.

Processing steps

1. Confirm the design

Our experts will communicate you the design drawings, confirm the CAD design pattern, and make the master template through CNC machining or some form of 3D printing (SLA/SLS)

2. Silicone mold

The mold is made of liquid silicone, which is poured around the master mold in the mold box. After curing and drying, the mold is cut, and the master mold is removed, leaving a negative cavity that is exactly the same as the original. This is the original silicone mold. To achieve extremely high precision, further polishing, primer sealing surface treatment, etc. are required.

3. Casting parts

The liquid plastic is poured into the silicone mold and cured in a constant temperature environment. The prototype part is cast.

4. Vacuum casting tolerances

The finished dimensional tolerances of vacuum cast parts depend on the accuracy of the master mold, the geometry of the part, and the type of casting material used.

A shrinkage rate of 0.15% is generally expected.

5. Assembly

Once all the prototype plastic parts are ready, we will assemble the complete product and the entire production cycle is completed within 3 days.

What are the characteristics of products produced by vacuum casting?

High precision

Vacuum casting can produce extremely fine products. Since the liquid material is poured in a vacuum environment, the generation of bubbles is minimized and the details in the mold can be fully replicated.

Smooth surface quality

During the vacuum casting process, the negative pressure environment helps the liquid material flow evenly, thereby reducing the generation of bubbles and defects. Such bubble-free castings usually have a smooth, non-porous surface and even do not require post-surface treatment to achieve high appearance requirements.

High transparency and good physical properties

Vacuum casting using transparent materials such as polyurethane resin can produce highly transparent products, which are suitable for applications requiring high transparency and optical performance (such as lamp covers, display panels, etc.).

Low production cost

Using silicone or polyurethane rubber as mold materials, these materials have low manufacturing costs and short production cycles, which are very suitable for small batch production and prototype testing.

Summary

Products produced by vacuum casting technology have been widely used in many industries due to their high precision, high quality and strong adaptability. Vacuum casting is your best choice for rapid prototyping. You don't need to spend a lot of money to make a prototype. You only need to invest a small amount of cost to produce the design for verification quickly. Kaierwo has 14 years of experience in vacuum casting rapid prototyping and has delivered 40,000+ projects. We provide you with the best customer experience and qualified products in accordance with ISO 90001 and ISO 13485 standards. You only need to upload your CAD drawings and we will create your design for you.