Vacuum Casting

11 Apr 2024
3 mins
Vaccum Casting

What is Vacuum casting?

Vacuum casting is a manufacturing technology that uses a vacuum to draw liquid casting material into a mold. It differs significantly from injection molding, which pushes liquid material into a mold using a screw.

The vacuum casting process offers significant advantages and is particularly useful for parts with undercuts or fine details.

The process starts with a master model, which 3ERP creates using one of its machining centers — through 3D Printing can also be used. This master model is then immersed in liquid silicone, which is cured and becomes the mold.

Once it’s cut and the master model removed, the silicone mold can be put to use. This stage involves pouring casting resin into the mold, as the vacuum draws bubbles and air pockets to ensure a smooth finish.

The resin part is then cured in an oven and removed from the silicone mold after cool down, which can be reused around 20 times.

Each cast part is an exact copy of the original master model. It’s a perfect solution for rapid prototyping and making small batches of quality parts.

Benefits of Vacuum Casting

Multiple components can be used from the master pattern within 24hrs which would reduce the product design prototyping stage, cutting time and cost on new product development

Urethane casting can be used to create small batches of high-quality injection molding type parts for prototypes or low volume end-use parts for low stress, relatively benign environments

A wide range of vacuum casting resins are available to suit various applications such as clear, rubbery, flame retardant, food-grade, and colored to suit

Resin type can be changed quickly without the need to retool to test various material types for a given application or part

Complex shapes and features can be accommodated by using multi-segment moulds & cores

Aluminum and brass in-mould inserts can also be used

Vacuum Casting Process

Step 1: Master building

Masters are 3D solids of your CAD designs. They are usually made by CNC machining or with 3D Printing. They are earning Master in 40° temperature. After finish and inspect the masters, we will move to silicone mold making.

Step 2: Mold making

Casting molds are made from liquid silicone. Half-Fill the casting box with liquid silicone, Heat the casting box until the silicone is fully cured and then allowed to cure in an oven for 16 hours. Fill with extra silicone liquid, which is also heated & cured. Once dried, the mold is cut open, and the Master removed.

Step 3: Make the parts

Poured the casting resins into the empty cavity to create a highly accurate copy of the original. It's even possible to over-mold with two or more materials. Silicone molds are typically suitable for 20 or so copies of the master pattern.

Characteristics & applications of vacuum casting

Vacuum casting is one of the most cost-effective ways to produce high Quality, low volume plastic parts which can be similar to injection moulding parts

The parts are especially suitable for form, fit, and function tests during the embodiment design stages, where they can be used for marketing, field user testing, and product design verification purposes

Many vacuum casting resins are commercially available, which can be used to create parts to satisfy a wide range of design requirements such as temperature requirements, different surface textures, hardness, etc.

Materials are also available to create parts that are fully opaque, translucent, or completely transparent

Sometimes high-quality wax masters can be made using vacuum casting for investment casting to increase the finer details of intricate features.

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Unionfab's Expertise

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