Vacuum casting is carried out under vacuum conditions to produce first class castings with no bubbles, smooth texture and no defects.
"Polyurethane casting, sometimes called vacuum casting, is a small batch casting process that is widely favored for its adaptability. Its use is critical for everything from medical devices to automotive and aircraft interior parts."
The vacuum casting process involves shaping a variety of air-free resins, including polyurethane, epoxy or silicone, into the desired shape. During this process, a pump or similar device will pull all the air out of the mold.
It offers many advantages over traditional manufacturing methods, including lower costs, faster production times, and the ability to produce complex parts with complex details.
Vacuum casting
Vacuum die casting is a process in which a certain vacuum degree is established in the cavity of the die casting model
| Standard capability | Description |
|---|---|
| Maximum build size | +/- 0.025 mm (+/- 0.001 in) |
| Standard delivery time | Up to 15 parts in 20 days |
| Dimensional accuracy | ±0.05 mm |
| Layer thickness | 1.5mm - 2.5mm |
How does vacuum casting work?
Vacuum casting process flow
1. Create 3D shapes or geometric shapes through modeling.
2.Use the 3D model as a guide to create a high-quality master model.
3.According to the master model, create a silicone mold.
4.The casting material is mixed and poured.
5.Finish castings after curing and demoulding.
3D Modeling
To begin the vacuum casting process, you first create a 3D shape or geometry through modeling. In order to achieve the best results, the principles of injection molding must be followed. Sometimes, 3D laser scanning is used to inspect parts and create 3D files.
Build Master Model
The 3D model is then used as a guide to create a high-quality master model. Although CNC machining was previously used for this purpose, additive manufacturing has become a faster and more affordable option. Alternatively, an existing cast model can be used as the master model without any additional modifications.
Make Silicone Mold
- Create a silicone mold after developing the main pattern:
- Once the master model is fitted with the necessary components, such as the core, inserts and gate, it is placed in the casting box and risers are added to ensure proper air escape during the molding process.
- Silicone is then poured around the master in the cast box and vacuumed dry so that it fills every detail perfectly.
- After the mold is cured in the oven at about 40 ° C for 8-16 hours, the box and riser are removed.
- Using a scalpel, the mold is cut cleanly to reveal the negative cavity of the part, and a wavy cut is used to ensure accurate alignment when producing multiple parts.
- Finally, it is important to select and use the best release agent to prevent problems such as viscosity and surface defects.
Casting materials are mixed and poured
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Before mixing, the polyurethane resin used for casting is usually heated to about 40°C. The mixing process involves mixing a precise amount of two-component casting resin with any desired pigment inside the machine. After mixing, pour the resin into the bowl of the machine.
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When the automatic pouring process begins, the casting resin and pigment mixture is thoroughly stirred and vacuumed for 50-60 seconds. The resin is then poured into the mold, still under vacuum pressure, to avoid any air pockets or gaps, ensuring that the mold is free of bubbles and the resin can flow smoothly into the mold.
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The vacuum state allows the removal of air pockets and other obstructions, making it possible to fill the mold smoothly and perfectly by gravity. This process helps prevent any problems that could weaken the strength or appearance of the finished product.
Casting curing and demoulding
After pouring the resin, the mold goes into a heating chamber for curing. Subsequently, the casting is removed from the mold and the sprue and riser are removed. Additional finishing is then performed.
Application of vacuum casting
Vacuum casting process is used in various industries because of its versatility. Its ability to produce complex and accurate components makes it ideal for delivering superior results.
1. Aerospace industry
Due to its accuracy, repeatability, and ability to handle complex details, vacuum casting can successfully manufacture precision aviation components, including fuel systems, air ducts, and aircraft exterior components.
2. Medical equipment
Vacuum casting is ideal for the manufacture of complex parts and components in the medical field, such as medical implants and prosthetics.
3. Automobile industry
Highly detailed automotive components, such as intake manifples, exhaust systems and body panels, can benefit from the precision and consistency of silicone vacuum casting in the automotive industry.
4. Food and beverage industry
Vacuum casting is commonly used by the food and beverage industry to produce food packaging, containers, cans, cups, bottles, glasses and other necessities in food production facilities.
5. Electronics industry
The shock and heat resistance of polyurethane makes vacuum casting the first choice for the manufacture of electronic device housings.
6.Consumer goods manufacturing
Consumer goods, such as toys and sports equipment, can be perfectly manufactured and suitable for application by the vacuum casting process.
