Vacuum casting process

Introduction

What is vacuum casting?

If you have a prototype that you want to make and don’t know the exact process to follow, you should try your hands on the vacuum casting process. However, you must make sure that you have the optimum temperatures and the materials required for this process.

Vacuum casting is almost the same process as the duplication of silicon mould. However, in this process, you require a vacuum pressure time of 5 minutes and a mold temperature of 60 degrees Celsius. Basically, this is a casting process for elastomers which uses a vacuum to draw any liquid material that you are using to bring out liquid material to the mold. Vacuum casting is also used in case there is an air entrapment or a problem with the mold that is being used. When there are intricate details in the mold that must be perfectly and efficiently filled, this process does it best.

Sometimes, the process is also called thermoforming because the manufacturing process uses and involves a lot of rapid prototyping where the plastic sheets used are preheated for batch manufacturing. The materials that are involved are heated to a certain extent beforehand so that the casting machine finds them soft and pliable. This is necessary for the vacuum casting process to work well.

How does the process work?

In short, plastic films and sand are sculpted over a pattern using heat, coupled with vibration and vacuum to form a shape in the form of a mould. This mould is used to shape the liquid that will be poured later in the process. This suction of the vacuum is used to hold this mould in the correct place until the mould has solidified completely and is ready to be extracted.

Here is the detailed process that is followed by vacuum casting:

• The pattern is mounted on a pattern plate in the form of a hollow vacuum box. Through this box, the holes are drilled in the shape of any concave features that might be present on the surface of the mould. A plastic film or heater are mounted above this pattern and the film is sucked down to get applied on the pattern plate
• A moulding box that has hollow and porous walls and a vacuum attachment is placed over the film-covered pattern and the box is filled with dry unbonded sand.
• Down gates and risers are used to make sure that the sand binds together well
• The vacuum is gently released from below and the metal is poured while maintaining the vacuum on the moulding boxes
• When the casting has completely cooled down, a slight pressure is applied so that the sand becomes free flowing and the casting falls effortlessly from the molding boxes.

What are the materials used in the vacuum casting process?

Components made using the vacuum casting process use a variety of different materials like polymers and resins. Polyurethane is one of the best choices for making engineering grade equipment using the vacuum casting process. This can also be used to make different grades of items and products with different and specific functionalities. Most polyurethanes can be treated at high temperatures. Along with that, there are specific variants of polyurethane that can be used according to the requirements of the manufacturer and the consumer.

Another type of resin that can be used with vacuum casting is rubber elastomer. These elastomers can be used with silicon moulds in the process of vacuum casting. Most of these compounds include silicon itself.

Other materials that may be used are polycarbonates and ABS resins for making different kinds of components.

Applications of vacuum casting process

Vacuum casting is widely used in the food and beverage industry to make tins and bottles out of different materials. The process is also used to make a variety of commercial products and household products.

• Commercial products: This process is widely used in packaging. Most of the products that are made with the vacuum casting process are mobile cases, sunglasses and packages for food and drinks.
• Food and beverages: The industry uses this process a lot to make packaging items for their perishables. Since this process can make the same vacuum casting products by the millions in a very short time, it is very popular in the consumer sector

These are some of the batch production examples where vacuum molding can be used.

Relevance of vacuum casting process in automobile, IoT and medical industry

Many industries, including the automobile, aircraft and electronic sectors have actively researched the process of vacuum mould casting in the recent years. The die-casting method is a process that is used to make a product. It is because of the simplified form and non-complicated process of making these products that the electronics, automobile, IoT and the medical industry is increasingly getting into this sphere. With the kind of precision and accuracy this process provides to the industries, the manufacturing of the same product in a large volume becomes easy, fast and affordable. Packing materials are used in all of these industries and it is packaging that the vacuum casting process is adept at. The manufacturing of packaging in all these sectors is the prime reason why the vacuum casting process is receiving a lot of research and development efforts. It is through the development of this process can these industries hope to develop their efficiency and productivity, and in turn, reduce their lead turnaround time.

Conclusion

Vacuum casting is a leading process that is used in important and key industries around the world. With the medical, automobile, technological and consumer industries getting behind the batch production applications of the vacuum casting process, we can hope that this technique is here to stay for the long run. Not only that, with the constant research and development that it is subject to, the efficiency and productivity of the technique with regard to consumer production is bound to increase dramatically. The quality of silicon molding in the industry increases every year, and with it, so does the efficacy of the vacuum casting process. Thanks to the reducing vacuum casting cost, more and more areas are becoming open to implementing it in their manufacturing process.