What is Vacuum Casting - Simply Explained | Wenext

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With a history of half a century, vacuum casting still plays its significant role to make prototypes and even complement other manufacturing processes. It is still an irreplaceable and valuable molding technique, and the industry needs it. Let&#;s learn what is vacuum casting, how does vacuum casting work, and vacuum casting products in this article.

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Part 1. What's Vacuum Casting?

Vacuum casting, refers to Urethane casting or Polyurethane casting, is a casting process for elastomers using vacuum to draw the liquid material into the mold, thus making plastics and rubber components. As an excellent adaptable manufacturing process, vacuum casting is capable of producing complex parts with intricate details. Making vacuum casting part is a shortcut for quality validation at early stage. It&#;s a solution to speed up product development process as vacuum casting can create small batches of high-quality parts in short time. And those parts are suitable for pre-launch product testing, functional testing and validation, concept models and prototypes, etc. Vacuum casting prototyping is an economical manufacturing solution, let&#;s take a look at the process of silicone vacuum casting.

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Part 2. How does Vacuum Casting work?

1. Master Model Building

First of all, producing vacuum casting prototypes require a high-quality master model with high dimensional accuracy. To ensure the final vacuum casting parts are the same as expected, creating flawless mater model is the vital foundation. Master model can be created by 3D Printing or CNC Machining, and dedicated post-processing, grinding, for instance, is necessary. These steps make sure that the master model is perfect to use. At Wenext, we will go through all details before making the master model, like design file checking to guarantee a manufacturable master model.

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2. Silicone Mold Making

Master model is ready to use. Then it&#;s time to pour liquid silicone into the casting box and fully immerse the master model. It takes several hours to cure the silicone naturally. After the mold is cured, cut open the mold and take the master model out of the mold. You will see a hollow space in the middle of the silicone mold, which fits the dimensions and specifications of the master model. Later on, the silicone mold needs to be cured again at a high temperature in an oven because the mold is still soft and sticky. Curing time would be based on size of the mold.

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3. Parts Producing

The final step is casting parts with the silicone mold. Before casting, clean the surface of the silicone mold again is necessary. Then spraying the silicone mold internal structure with special release agents, attach tape to the edge, and even insert steel bars inside for large mold. All these steps make sure that mold release without damages. Casting materials mixture should be done in advance. Then fully fill the mold with materials, the process is done in a vacuum chamber for degassing, ensuring air bubbles are removed. Afterwards, move the parts in an oven for curing. Curing time is based on part size as well. The vacuum casting part can be removed from silicone mold after cool down.

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Part 3. Vacuum Casting Pros and Cons

Pros

1. Vacuum casting is the cost-effective method to create small bathes of high-quality parts for prototypes.

2. Material flexibility. A variety of vacuum casting resins with various colors are available and accessible, meeting the needs of different applications.

3. Parts with complex structures and intricate details can be created by vacuum casting easily and efficiently.

4. High precision and low cost.

Cons

1. Shrinkage and rounded edges will occur.

2. The surface finish may have air bubbles, and dedicated post-processing is necessary.

3. The silicone mold will wear out quickly.

4. Regular cleaning of the mold is necessary.

5. The initial set-up could be a high investment, depending on tools, equipment, etc.

You will get efficient and thoughtful service from thingyfy.

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Part 4. Vacuum Casting Applications

1. Consumer Products

Utilizing vacuum casting to produce consumer products such as stationery products, pens, sunglasses and cases, etc.

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2. Food and Beverage

Vacuum casting is being able to fast prototyping food and beverages packaging, bottles, cans, and other food containers.

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3. Electronics

Using vacuum casting to produce housing for electronic devices, such as keyboard, charger, and power bank, etc.

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Part 5. Vacuum Casting Service at

Wenext

Besides on-demand 3D Printing and CNC machining services, we provide vacuum casting for small batch production. We produce high-quality and high precision vacuum casting parts fast, and offering different materials and multiple color choices. If you are looking for vacuum casting service, please try our instant quoting system and upload your files seamlessly. We will be with you shortly and make sure that the production process of your parts go smoothly. for more information.

What is vacuum casting?

Vacuum casting, also known as urethane casting or polyurethane casting, is a casting process used to produce production-quality parts from a range of thermoplastics, rubbers and resins without the cost or lead time required for production tooling or &#;hard tooling.&#;

Where injection mould tools are made from metal (steel, aluminium etc), vacuum casting uses soft silicone moulds. The process is ideal for creating a small series of parts and is often used in the early stage of product development before committing to injection moulding.

In this introductory guide, we give you an overview of the vacuum casting process, materials used, considerations, and key benefits and limitations of this form of manufacturing.

It is a cost-effective alternative to injection molding, which requires expensive tooling costs and long lead times. Vacuum casting produces accurate and durable parts quickly and at a fraction of the cost of traditional methods. The process is often used to produce prototypes and small production runs of parts.

How does vacuum casting work?

Overall, the process involves 3 main stages: building a master model, creating the silicone tool, and producing the parts.

Step 1: Building a master model

First, a high-quality master model with high dimensional accuracy is required to ensure. Typically, this master model is made via 3D printing or CNC machining, then sand, painted and primed to achieve the desired surface texture and quality. Every tiny detail will be replicated in the final vacuum casted part, so it&#;s essential to create a flawless master model.

Step 2: Creating the silicone mould tool

The master model is then suspended in a casting box in which liquid silicone is poured around it. The molten silicone is allowed to cure inside the casting box, which is maintained at 40*C, for about 8-16 hours. After it has solidified and curing is completed, the mould is cut open and the master model is taken out leaving a hollow space in the middle of the silicone mould, which fits the dimensions and specifications of the master model.

Step 3: Producing the parts

The &#;hollow&#; mould is filled with polyurethane (PU) resin using a funnel for uniform distribution and to prevent any air bubbles from forming. The mould is then sealed left in a casting machine at around 70°C to cure. The shaped material is then cooled, removed from the mold, and post-processed as necessary. This process can, on average, be repeated 10 to 20 times. Going beyond these limits will cause the mould to gradually lose its shape, affecting dimensional accuracy.