Silicone rubber molds have become increasingly popular in small-batch injection molding production due to their cost-effectiveness and efficiency. When it comes to producing small quantities of parts, particularly for resin materials, the use of RP prototypes and silicone rubber molds through resin vacuum injection molding offers significant advantages. This process not only shortens production time but also reduces costs, making it ideal for achieving high-quality results in a faster and more economical manner.

Applications of Silicone Rubber Molds

For small to medium production runs, the use of silicone rubber molds in resin vacuum injection molding is an excellent solution. By creating a silicone rubber mold from an RP prototype, the production time for parts can be significantly reduced, and manufacturing costs can be lowered. Additionally, the silicone rubber mold enables the efficient production of parts with minimal waste.

For parts without intricate ribs or small holes, the silicone rubber mold process can produce more than 50 pieces of a resin part. Below is a detailed breakdown of the process used in silicone rubber mold resin vacuum injection.

Resin Vacuum Injection Process Using Silicone Rubber Molds

1. Cleaning the Silicone Rubber Mold Before beginning the injection process, it is essential to clean the silicone rubber mold thoroughly. This step ensures that any residual materials from previous uses or debris in the mold are removed. The mold should also be preheated to a suitable temperature to ensure smooth filling of the mold during the injection process. To ensure complete filling, a series of vent holes should be added to the higher areas of the mold, particularly away from the injection gates.
2. Spraying Mold Release Agent To aid in the smooth removal of parts from the mold, a mold release agent should be sprayed onto the mold cavity surface. It is important to ensure that areas such as deep grooves and holes, which are more challenging to demold, are well-covered. For transparent materials, however, it is advisable to skip this step, as the release agent can interfere with the clarity of the material.
3. Resin Metering The amount of resin required is generally estimated based on the weight of the prototype. For the initial pour, the resin’s weight is typically calculated by multiplying the prototype’s weight by a specific coefficient. Once the initial amount is determined, the resin and hardener are measured according to the specified ratio. This ensures that the correct quantities of each component are used, optimizing the final product’s properties.
4. Vacuum Mixing and Injection To improve the density and fill capacity of the molded part, a vacuum environment is created before injection. This process serves two main purposes: removing any dissolved air from the resin and hardener mixture and eliminating air pockets within the mold cavity. The duration of the vacuum process depends on the part’s size and specific requirements. Once the vacuum is achieved, the resin and hardener are mixed thoroughly and injected into the mold cavity.
5. Curing in a Temperature-Controlled Environment After the resin is injected into the mold, the mold is removed from the vacuum chamber and placed into a temperature-controlled curing box. The curing process time will vary depending on the size of the part and the type of resin used. The mold remains in the curing box for the specified duration, ensuring that the resin solidifies and fully cures. Once the curing process is complete, the part is ready to be demolded.
6. Post-Processing of the Prototype After the part is removed from the mold, further post-processing may be required before the part is ready for use. This may include removing any excess resin from the gating system, sanding, polishing, or even painting the part to achieve the desired finish.

Conclusion

The use of silicone rubber molds for resin vacuum injection molding offers several benefits, particularly for small-batch production. This method not only reduces costs by minimizing material waste but also significantly shortens production times. With the ability to produce high-quality parts quickly and efficiently, this technique is widely used in industries requiring rapid prototyping and low-volume manufacturing. By following the detailed steps of cleaning, spraying release agents, resin metering, mixing, injection, curing, and post-processing, manufacturers can achieve excellent results with silicone rubber molds and resin vacuum injection molding.