Posted on: Sep 11, 2018, | By Candy, WayKen Marketing Manager
Vacuum casting or urethane casting is a popular casting technique of elastomers and involves the use of vacuum in order to transfer the liquid material in the mould. Vacuum casting is commonly used in the manufacture of prototypes and products where the designs are complex and the air entrapment may cause a major issue in the final product.
Vacuum Casting in China
China is a world leader in vacuum casting hence, you may find many different vacuum casting services scattered all over China. Vacuum casting in China is one of the most commonly practised rapid prototyping technique. With cheap raw material and experienced labour, vacuum casting in China is carried out with ease. With that being said, we welcome you at Wayken, your one-stop solution to all your prototyping needs. At Wayken, we make use of state of the art urethane casting supplies and offer the best vacuum casting service in China.
A Brief History
The vacuum casting of urethane using silicone mould was developed back in the mid-1960s in the former German Democratic Republic. Vacuum casting technique was then sold to Japan in the 1970s where it was primarily used for the manufacture of various automotive parts. It was then reintroduced in Europe and now is commonly used for the Research and Development departments of all the major production companies.
The introduction of thermosetting plastics in 1980 brought these plastics to the vacuum casting technique as well. These plastics have the ability to perfectly mimic the properties and the appearance of the materials that are used in the mass production. Since the 1980s, the advancements and the modern application of CAD have allowed for the vacuum casting to be carried out faster, cheaper and accurately.
The Process of Vacuum Casting
Vacuum casting is a reliable and flexible casting process that can accommodate complex designs. Due to its excellent reliability, vacuum casting services are commonly used by companies for their prototypes and products. For the vacuum casting process, a high-quality master model is required. This can either be a finished industrial part itself or a dedicated model can be created for the clients.
The model is usually created using stereolithography. It is crucial that the master model is of ultimate quality and precision as any design flaws in the master model will be transferred over to the casted prototype/product. All the high-end urethane casting services make sure that the master model is picture perfect as it is the first step towards an excellent prototype/product.
Once the master model is obtained, it is encapsulated inside a two-part silicone mould and the cured to very high temperatures. After the curing is done, the mould is opened symmetrically. The master model creates a hollow area within the mould which matches exactly to that of the master model. The mould is then carefully placed within a vacuum chamber (hence the name, vacuum casting).
Once placed inside the vacuum chamber, the mould is then filled with the required material. The most common material for the vacuum casting is urethane. Urethane casting makes sure that the prototype replicates the specific characteristics of industrial grade materials such as glass-filled nylon, polycarbonate and high-density polyethene.
Once the mould is filled with urethane, it is sealed with a high-intensity vacuum in order to eliminate any air bubbles. The cast is then cured and mould is removed. Once the mould is removed, the prototype or the product can be painted accordingly.
Benefits of Vacuum casting
There are several benefits of using vacuum/urethane casting as compared to other prototyping techniques. For the aesthetic purposes, the prototypes/products manufactured by the urethane casting services can be coloured and branded easily to the company’s needs. Urethane casting supplies can also be mixed with other materials in order to give a different product finish. The powder form of gold, bronze and even marbles. This way of finishing is cheaper as compared to other methods.
The turnaround time in the urethane casting is very fast which makes it the technique of choice for many companies. Functional wise, urethane casting supplies can be added with materials of certain properties such as electrical resistance, shock resistance and fire retardation.
While many techniques struggle with manufacturing parts of very small wall thickness and highly complex designs, vacuum casting has the ability to manufacture those parts rapidly with high precision. As compared to plastic injection moulding and other modern techniques for prototyping, vacuum casting is very economical for one-off prototypes and short-run batches.
The parts manufactured via this technique has striking visual and mechanical resemblance with injection moulding, however, vacuum casting is suitable for both low volume plastic parts manufacturing (lesser than 100 parts) as well as rapid prototyping. Around a weeks’ time is required to manufacture around 50 functional prototypes. For more than a dozen parts, Vacuum casting is rendered more relevant in comparison to CNC machining or 3D printing.
The Machine Used in Vacuum Casting
The machine that is used in the vacuum casting allows for rapid duplication of plastic parts via silicone mould. The machine also has a depressurizing chamber to suck out all the air present inside the mould. This creates the vacuum inside the cavity necessary to avoid any air bubbles inside the prototype/product. Mostly, the vacuum duplication in vacuum casting is controlled via industrial grade CAD software.
Technical Specifications for Vacuum Casting
|Minimum wall thickness||In order to ensure that the mould is properly filled, the minimum thickness of 0.75 mm is necessary. However, at least 1.5 mm is recommended|
|Typical quantity||Up to 25 copies per mould|
|Surface structure||High-quality surface finish|
|Lead time||Up to 50 copies within a week|
Ideal Application for Vacuum Casting
Vacuum casting is one of the ideal and preferred methods for prototyping and product manufacturing. Some of the common industries and products that rely on this technique are as follows;
- Prosthetic and medical devices
- Automotive industry
- Aerospace industry
- Product marketing
- Function testing
- Home décor parts
- Rapid plastic prototyping