All You Need to Know about Vacuum Casting

Last Updated on June 28, 2022 by Leizi

Vacuum casting is a process in which plastic parts are made from silicone molds under vacuum. You may have heard it by other names as well – Polyurethane Casting and Polyurethane Casting. This process is often used to make small batches of prototypes.

What is the process flow of vacuum casting?

Step 1: Create prototypes. Before making vacuum cast parts, we need some prototypes made by CNC machining or 3D printing. 3D printing, including SLS and SLA printing, can produce prototypes at higher speeds than CNC machining.

Besides that, you can ship the samples directly to your production partner and make silicone molds based on the samples. Whether choosing CNC machining or 3D printing to create vacuum cast prototypes, we need to guarantee a high quality finish. Because it will affect the accuracy and quality of the vacuum casting afterward.

Step 2: Make the silicone mold. Hang the prototype with gates and inserts on the parting line of the mold casting frame. The next step is to extract the excess air from the liquid silicone and pour the silicone around the master mold until it completely covers the master mold.

Making Silicone Mold

Then all we need to do is – put the silicone mold in the oven and wait for it to solidify. Different sizes of silicone molds require different curing time from 1 hour to 4 hours. Once the liquid silicone is fully cured and dry, we cut the silicone mold along the parting line and take out the prototype.

Step 3: Pour resin. Before pouring resin, we usually need to preheat it to a specific temperature. Then we mix the resin and pigment in a certain proportion and put it in the bowl inside the pouring machine.

Step 4: Demoulding
After the last pouring step is completed, we can directly take the cured casting out of the silicone mold and remove the excess gate.

What are the applications of vacuum casting parts:

As a popular plastic production process, we can see the use of vacuum castings in a wide range of fields, including medical devices, consumer products, aerospace parts, automotive parts, including bumpers, decorative parts, and more. Through continuous testing of prototypes of vacuum castings, we can use this to validate designs and concepts.



What are the advantages of vacuum casting?
1. Affordable. In the vacuum casting process, molds are made from lower-cost resins. During the whole process, the required labor cost and material cost are low.
2. Good surface cleanliness.
3. The processing speed is fast.

Ruitai’s vacuum casting capabilities include:
1.Quantity: One silicone mold can make about 20 castings. For a project, we can do small batch vacuum casting parts from 10 to 200 pieces.
2. The largest size is 2.5m*1.4m*1.2m, and the smallest is 5mm*5mm*5mm.
3. Accuracy: As for vacuum castings, the accuracy we can achieve is ±0.3mm.

Ruitai team is glad to assist your project anytime as long as you send us 3D files.