Vacuum casting is a prototype manufacturing process that uses silicone molds to quickly create urethane casting parts for the production of small batches of functional parts.

What is Vacuum Casting?

Vacuum casting (also known as urethane casting) is an economical alternative to low-volume injection molding of plastic parts and can be used to closely simulate final molded parts or finished products. Generally, molds are made from silicone rubber and use CNC machining or SLA part as a master pattern. These molds duplicate intricate details and textures and give consistent finishes from one part to the next. You can get production-like results including mechanical traits, wall thickness, colors, and surface finishes.

Advantages of Vacuum Casting

Low cost for silicone molds

Cast urethane parts are made of cheap molds, eliminating the need to invest in expensive and time-consuming metal tooling. It is a cost effective method for making high quality prototypes and low volumes of parts.

Fast delivery

Up to 50 functional cast urethane parts can be produced in 10 to 15 days when you choose vacuum casting.

A wide selection of materials

Casting resins materials range from soft and flexible to rigid and impact-resistant, as well as colored and clear.

High precision and fine details

Vacuum casting provides end-use parts of high precision and fine details with production-level quality.

Excellent surface finish

Urethane casting can provide better surface textures compared with CNC prototyping or 3D printing.

Fast Short-Run Production Option For Low Volume Plastic Prototype Parts

How Vacuum Casting Works

The vacuum casting process has three steps: master pattern, molding, and casting.

Step 3. Casting Process

Paste tape in a flat position around the master, so that it is easy to open the mold later, which will also become the parting surface of the final mold.

The master model is suspended in a casting box and placed with plastic rods to set gates and vents.

Liquid silicone is poured around the master and removal all air, creating a vacuum chamber to ensure the master mold is free of air bubbles. Then is cured liquid material in an oven, at a temperature of 40℃. It generally takes 8-16 hours depending on the volume of the mold.

Once the silicone rubber is cured, cut open the casting box, remove the master model from the silicone to form an empty cavity, and the silicone mold is made.

JingXin standardized operational procedures assure accurate part replication and consistent mechanical properties. Our vacuum casting technicians to control all operational parameters: mixing, de-gassing, stirring, preheating, casting, and de-molding, allowing for near-perfect copies of the master pattern to be created. The manufacturing processes of vacuum casting parts are as follows:

Vacuum Casting Materials

Urethane resins are polymers with a wide range of properties and use. JingXin offers various urethane materials to meet your applications, including Hei-Cast from Japan and Axson from France. Materials with certain properties are similar to engineering production plastics, such as ABS, PMMA, PC, PP, PA, and so on. Casting parts can be varied from transparent, translucent to colored, and from soft rubber to hard plastic. Various materials contain those impact-resistant, high-temperature resistant (120℃) or fire-resistant (UL94-V0), glass-filled resins, and different hardness silicone.

Step 2. Silicone Mold Making​

Casting molds are made from liquid silicone resin, also known as RTV molds. The chemical stability, self-releasing properties and flexibility of silicone rubber are excellent in that it gives minimal shrinkage and carries fine details effectively from master to mold. The mold making process starts as follows:

First, put the silicone mold into the oven and preheat it to 60-70°C.

It is very important to choose a suitable release agent before closing the mold and use it correctly to avoid stickiness and surface defects.

Prepare the polyurethane resins to preheat them to about 40°C before use. Mix two-component casting resins in exact proportions, and then fully stir and degas for 50-60 seconds under vacuum to avoid air pockets or bubbles

The resin is poured into the mold inside the vacuum chamber under computer control and cured again in the oven. Average cure time: 1-3 hours for small parts and 3-6 hours for big parts.

Remove the casting part from the silicone mold after curing. Prepare to repeat this vacuum casting work cycle.

Step 1. Master Pattern Making

The quality of the casting urethane parts is determined by the quality of the master pattern, which is best machined by CNC when you need to hold tight tolerance, glossy finish, or even optically clear. In addition, we also will consider making the master by SLA for those parts with more complex shapes and structures.

We can paint parts surface for texture or satin effect to simulate the final mold texture of the product. The silicone molds will copy the details and textures from the original master, so the cast urethane parts will come out the same as the master model without any extra finish on the surface.

Address: No.68, DaCao Pu 2 Road, PingHu Town,                                           LongGangDistrict, ShenZhen city, GuangDong, China.

Contact: Mr. Lin

Mobile: 8613501567685

Tel: 0755-28452912

Fax: 0755-28453509

E-mail: [email protected]

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