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Overview: How Vacuum Casting works?

What Is Vacuum Casting?

This is a casting process for elastomers which uses a vacuum to draw any liquid material into the mold. Vacuum casting is used when air entrapment is a problem with the mold. Additionally, the process can be used when there are intricate details and undercuts on the mold. Also, it is applied if the material used to make the mold is fiber or a reinforced wire. The process is sometimes called thermoforming because the manufacturing process involves rapid prototyping where the plastic sheets are preheated. The materials are preheated in an automated vacuum casting machine until they are soft and pliable.

How Does Vacuum Casting Work?

Plastic films and sand are sculpted over a pattern using heat, vibration and vacuum to form a mould in the shape of the component to be cast. Suction by vacuum is used to hold the mould in place until the molten metal has solidified.
Have A High-Quality Master Model
Cure Process
Filling The Resin
Final Cured Process

Vacuum Casting processes


Vacuum Casting processes
Copyright: Open University
Vacuum Casting processes
Copyright: Open University
Manufacture:
1.An alternative to “conventional” sand casting processes, with the advantage of a cleaner working environment. Suitable for either “jobbing”, or fully automated production, although ideally the foundry should be specifically designed for the process.
2.The foundry needs to be specially designed around this process, with special moulding boxes with integral cavities and vacuum lines to accompany moulds. The process is patented and licensed from Japan. Relatively few non-Japanese companies have adopted the process.
3.Uses dry, unbonded silica sand which requires little compaction and is almost fully reclaimable; a major economic advantage.
4.The ethylene vinyl acetate film is 50–100 µm thick and is heated to 100˚C; the temperature is judged by the loss in opacity of the film. After thermal softening the pattern must be uniformly coated, without wrinkles or tearing.
5.Patterns of cast aluminium are cheaper than for “bonded” sand moulding and last longer, since the sand does not come into contact with the pattern.
6.Gating systems should allow the cavity to be filled rapidly. Vents and risers must be located in such a way that the unfilled portion of the casting cavity is at atmospheric pressure, to allow the gases formed in the initial stages to escape to atmosphere.
7.Knock-out is easy, since removal of the vacuum allows the sand to flow out of the box.
8.When casting cast iron, or other similar medium to high melting point materials, the surge of hot air and mould gases released at knock-out produces a cloud of fine silica dust, which is a serious environmental health hazard.
9.Products that have been produced include manhole covers and tractor sprockets.

Ideal applications for Vacuum Casting
  • Pre-launch product testing
  • Small series of housings and covers
  • Concept models and prototypes

Benefits Of Vacuum Casting

The following are advantages of using vacuum casting on duplicating products.
High Precision And Fine Detail To The Finished Product
When you are using silicone as the mold to your products. It ensures that the final product has great attention to the details. The final product ends up looking like the original product.
Every attention to detail is considered and taken into account. Even when the original product has the most complex geometry, the final product looks like the original.
High Quality Of The Product
The products made using the vacuum casting method are of high quality. Also, the use of resin allows you to choose the right material to be used in making of the final product.
This allows you to have a wider choice of flexibility, hardness and rigidity you want in your products. Also, this has a great influence on the final appearance of the product since the material used plays a major role.
Lowers The Production Costs
Using the vacuum casting process to make the product is more economical. This is because the process uses silicon to make the molds. Silicone is affordable as compared to aluminum or steel and makes great final products.
Moreover, the material allows you to make more products from the mold. This makes this process more cost effective as compared to the use of 3D printing.
A Great Method When You Want To Meet A Deadline
This method is fast, and it takes you less time to finish making the finish products. You can take seven to ten days to make around 50 functioning prototype parts.
This method is amazing when you are making a lot of products. Additionally, it is great when you are working towards meeting a deadline.

Technical Specifications

Requirement Specification
Standard lead time Up to 10 copies within 15 working days
Standard accuracy ±0.3% (with a lower limit on ± 0.3 mm on dimensions smaller than 100 mm)
Minimum wall thickness To ensure that the mold is filled properly, a wall thickness of at least 0.75 mm is necessary. For best results, we recommend a wall thickness of at least 1.5 mm
Maximum part dimensions The size of the mold is limited by the dimensions of the vacuum chamber (1900 x 900 x 750 mm) and by the volume of the product (maximum volume: 10 liters)
Typical quantities Up to 25 copies per mold (depending on the mold’s complexity and the casting materials)
Surface structure High-quality surface finish comparable to injection molding

The table below depicts the general tolerances for industrial-grade vacuum casting services. Stresses during the build, support strategy and other geometry considerations may cause deviation in tolerances and flatness. Improved tolerances may be possible with a manual quote review, after successful completion of a prototype build, and must be approved on a case-by-case basis.

Our standard surface finishes

Here is a list of standard surface finishes. For custom surface finishes such as electroplating or polishing, please contact sales@pcbway.com.
Spray painting
Get painted according to the color pattern provided by the customer (Including matte paint, high-gloss paint, electroplating-imitation paint, varnish, leather paint,etc).
Spray painting
Polished
The surface texture is polished in a variety of ways to meet the actual needs of customers. The transparent parts can be polished accordingly to improve transparency and light transmittance.
Polished
Electroplating
Provide electroplating services, improve the overall strength of the parts, provide metal-like surface texture, and make it have certain metal characteristics.
Metal plating
Inlay nut
At the specific bottom hole position that needs to be processed, the internal thread is processed.
Inlay nut
Glazing assembly
The surface of the part is glazed to better imitate the appearance of handicrafts. Have mature assembly experience to ensure the overall display of the product.
Glazing assembly
Reinforced coating
The unique outer coating processing ability improves the strength of the product structure, reduces external wear, and can better avoid damage caused by normal storage and use.
Reinforced coating
Testing Service
A variety of measuring equipment provides reasonable measure services according to the actual needs of customers.
Testing Service