Vacuum Casting is a casting process that uses a vacuum to produce a nonporous, bubble-free batch of prototypes.
You design your prototype, and the mold required. And, you use that mold to make prototype batches.
Vacuum Casting, used generally for elastomers, is a casting process where the liquid is drawn into the mold using vacuum and gravity. Space ensures no porosity arising out of air entrapment and that the liquid material flows directly through the mold cavity. The molten metal is poured into the mold from a certain height to ensure the liquid material runs down under gravity and rises through the risers. The risers ensure that the image is evenly filled.
After the mold cavity is filled evenly, the vacuum is neutralized by air inflow. The mold is then kept closed for the curing process. After 45 minutes to 4 hours of the curing process, the final product is ready. The excess materials, flash, and risers are removed and the final part extracted.
Steps of the casting process
There are at least three distinct steps in the process of vacuum casting:
– First, one original sample or prototype is developed.
– The mold is made with PUR or silicone.
– The mold is used to make a small batch of prototypes or final products. The final products are identical to the original prototype with utmost precision.
Use of Vacuum Casting
- In the food and beverage industry, vacuum casting is used to make packaging prototypes.
- Among household products, it is used to make pens, sunglasses, and other everyday items’ packaging.
- In industrial machinery, it is used to make hinges and automotive parts.
- In consumer electronics, it is used to make mobile phone cases, keyboards, and housing for all other kinds of electronics.
Quality of product in Vacuum Casting
The use of silicone in vacuum molding makes sure the final batch of prototypes is identical to the first sample with every minute detail taken care of. And the precision of the final batch is not dependent on the geometrical complexity of the original sample. Hence, the final products are top-notch with desired texture, shape, flexibility, and attention to detail.
Cost and speed
In vacuum casting, the initial fixed cost is relatively low. This ensures you are not financially affected during your prototype development. While the per-unit cost is higher than in injection molding, the less tooling cost proves effective and provides flexibility to your prototype development process.
The material used in the vacuum casting process can be of varying density, rigidity, flexibility, and hardness. The materials include ABS, PC, PP, PMMA, silicone rubber, and other temperature resistant materials.
As for the mold, generally, polyurethane (PUR) is used. PUR of multiple grades is available with different color choices and different flexibility and hardness. The shore A range is soft and flexible, while the shore D range is hard and rigid.
The final product is of the utmost quality and accentuated finish. The properties of the products include:
- Heat and fire-resistant
- Colors, tints, and hues
- Flexibility and rigidity
- Range of surface finishes: matt, gloss and satin finish.