Vacuum casting is one of the rapid mold manufacturing techniques (RT). It takes advantage of rapid prototyping technology and the development of new materials.
Vacuum casting technology has greatly reduced the new product development cost, developing cycle time. It is especially suitable for the trial production of small batches of plastic products from 1 to 25 pieces.
two-component polyurethane PU. Materials currently used: AXSON polyurethane resin, Hei-cast polyurethane resin.
similar to ABS, PP-like, TPU-like, nylon-like, PMMA/PC transparent parts, soft rubber parts (40-90shord D), high temperature resistant parts (150 ° C), fireproof materials, etc.
Tools used in vacuum casting:
Engineers use pliers to close and separate the mold, making it easy to remove the cured sample from the mold.
2. Muti-mode vacuum machine:
Put the mold that has been injected into the mold material into the vacuum machine, and then extract the air in the cavity, and the air in the silicone mold that has been injected into the material is also discharged, so that the surface of the cured product will not have bubble.
3. Mold pressure cylinder:
Put the mold that has been vacuumed into the pressure cylinder, and add a certain pressure to the inside to make the mold and product better shape.
Vacuum casting process:
1) We put the mother parts made by CNC or 3D printing(SLA, SLS )processing into the center of simple mold
2) Then pour liquid silicone into the mold
3) Divide the silicone mold into two parts with a sharp blade, remove the prototype from the cured silicone mold, and the remaining hollow cavity is the shape of prototype
4) Inject the liquid compound material into the mold cavity, when the material is solidified in the mold, you will get a sample prototypes.
It sounds very easy but the process is opposite, a slight change in temperature, pressure, may lead to vast difference in size.
- Pre-heating of the silicone mold:
The silicone mold need to be heated to 60-70 ° C in advance. If the mold temperature is too low, the curing is incomplete and the physical properties are poor. The mold temperature is related to the dimensional accuracy of the prototype directly, but an experienced engineers partnered with HITIONS can always make it.
- Pre-defoaming of castables:
Liquid A and liquid B were vacuum degassed in a vacuum box for more than 30 minutes.
Place the containers containing the A and B liquids in the work chamber. After the working chamber is evacuated, stir the liquid B from time to time to defoam for 5-10 minutes, then pour the liquid A into the B liquid for 30-40 minutes, and then poured into the silicone rubber mold quickly. Regain to atmospheric pressure in 30 to 60seconds after mixing quickly.
After 30-60 minutes of curing in an oven at 60-70 ° C, the mold can be released. If necessary, perform secondary curing for 2-3 hours in an incubator at 70-80 °C.