What Is Vacuum Casting?
Urethane casting or Polyurethane casting uses silicone moulds to make plastic and rubber components under vacuum. It is an extremely adaptable manufacturing process capable of mimicking the injection moulding to produce complex parts in polyurethane resins and cast nylon.. 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.
Vacuum Casting Process
Step 1. Master Patterns
Patterns are 3D solids of your CAD designs. They are usually made by CNC machining or with 3D plastic printing such as SLA/SLS. You can supply your own patterns or we can make them for you. Patterns need to be able to withstand heating to 40°C
Step 2. Making the Molds
Casting molds are made from liquid silicone. This silicone is poured around the master pattern inside of a casting box, and then allowed to cure in an oven for 16 hours. Once dried, the mold is cut open and the master removed, leaving behind an empty cavity in the exact negative shape of the original.
Step 3. Casting Copies
Your choice of casting resins can now be poured into the empty cavity to create a highly accurate copy of the original. It’s even possible to overmold with two or more materials. Silicone molds are typically good for 20 or so copies of the master pattern.
Vacuum Casting Tolerance
The finished dimensions of vacuum cast parts are dependent on the accuracy of the master pattern, the part’s geometry and the type of casting material used. Generally a shrinkage rate of 0.15% is to be expected.
Advantage of Vacuum Casting?
When it comes to vacuum casting, there are a number of manufacturers to choose from. Choosing the right one is essential for getting exactly the results you expect. Here are several reasons to choose Star Rapid for your vacuum casting needs.
✓Low cost
✓Good for small order
The cost is low, the product production cycle is relatively short, the waste is less, and the processing cost is much lower than CNC machining and 3D printing.
Suitable for small batch product processing and production, after making an original version, it can be copied according to the original version
✓Good mold making operability
✓The probability of processing failure is small
Good mold making operability. After curing, the soft molds are all transparent or translucent, and have good tensile strength, which is convenient for cutting and splitting.
The probability of processing failure is small. As long as there is no problem with the original, the copy will not go wrong.
✓Good repeatability
Good repeatability. The silica gel used for molding has good fluidity before curing, and with vacuum degassing, it can accurately maintain the detailed structure and decoration of the model.
The Material for Vacuum Casting
| Material | Type | Color | Hardness | Physical Properties |
| ABS-liked | DPI8150 | Ivory | N/A | Good impact, can resist to 70°C |
| Rubber-liked | 906 | White | N/A | High strength, can be easily colored with CP pigments |
| PC-liked | 527 | Transparent | N/A | good impact, high transparency, high reproduction accuracy |
| ABS-liked | PX-223HT | Black | N/A | Low viscosity, superior heat and impact resistance |
| ABS-liked | 6160 | Light Yellow | N/A | Good impact, can resist to 200°C |
| ABS-PP | 5690 | White | 50/60/70/80 | Good impact, flexural resistance |
| PMMA-liked | 5210/521 | Transparent | N/A | Superior heat and impact resistance |
| ABS-liked | 8263 | White | N/A | Good impact, flame retardant |
| Rubber-liked | 8400 | White/Black | 15-90 | High strength, can be easily colored with CP pigments |
| ABS-liked | PX5118 | White | N/A | Good impact, can resist to 70°C |
| PC-liked | PX-210 | Clear | N/A | Good impact, flexural resistance |
Robotics prototype
Robot prototyping is the process of creating the first version of a robotic design. Prototypes are built by the system analysts to test a new design and increase precision. In this perspective prototyping allows testing the features of a real system instead of a theoretical one. In robot prototyping category materials and equipment you can use in robot prototyping processes
Medical device prototype
We use the term prototype to mean anything that is created to test a specific concept. This could be something as simple as a mock-up foam handle for human factors testing or as complex as a functional heart valve for life-cycle testing
FAQ About Vacuum Casting
1, What is the lead time?
Our lead time is about 5-12 days, according to the quantity.
2, How to get a quote?
Please send your 3d drawing(STP, IGS, STL, OBJ, X-T…) to us, and tell us the material, surface treatment and quantity, then we will quote to u within 2 hours.
3, How many pieces can be produced by one mold？
One mold can produce 15-20 pcs parts.
4, What should we do if you receive defective parts?
If you received the defective parts, please send us the photos, if it’s caused by us or shipping problem, we’ll redo or total refund.
5, What is the max size we can do?
The max size we can do is 2000*1200*1000mm
