Polyurethane Vacuum Casting
Polyurethane Vacuum Casting
RpProto provides a complete vacuum casting and silicone molding service, creating master patterns and cast copies with your CAD files. Cacuum casting is excellent way to make a few to hundres of prototypes for function testing, display demos, and concept validating. We produce high-quality molds at a low cost, and we also provide painting, sanding, and pad printing services.
Contact us now to get the best casting service in China.
What is Vacuum Casting
Vacuum Casting uses the original product to make a silicone mold in a vacuum, and then pours it with PU material to create a replica of the original.
Vacuum Casting Process
2. Positioning of the model in a box and casting of silicon
3. Mold cutting and RP model removal
4. Polyurethane or other material casting
5. Printed model with inlet to be removed
Advantages Of Vacuum Casting
Molds can be made in a few days, depending on specification and volume.
Cast copies are highly accurate with excellent surface texture
Silicone molds are durable for 30 or more copies before they need replacing.
Since silicone molds are cheaper than the tooling for injection molding
Coloring pigments can be added to the resin for a variety of color options.
How does vacuum casting work？
Before making the silicone mold, you need to make an original version, which can be made by cnc processing or 3D printing. Start making the silicone mold, and mix the silicone and curing agent evenly. The appearance of the silicone mold is a flowing liquid, and the component A is silicone. The B component is the curing agent.
Vacuum and bubble removal treatment:
After the silica gel and the curing agent are evenly stirred, perform the vacuuming to remove the bubbles. The vacuuming time should not be too long. Under normal circumstances, it should not exceed ten minutes. If the vacuuming time is too long, the silica gel will solidify immediately, resulting in a cross-linking reaction. The silica gel becomes piece by piece and cannot be painted or poured.
Painting or operation process:
The silica gel that has been evacuated and evacuated can be brushed or poured. Pour it on top of the product (Note: The product or model to be copied before pouring the silica gel must be coated with a release agent or release agent). Then apply the silica gel on the product. The application must be even. After 30 minutes, paste a layer of gauze and weft cloth to increase the strength and tensile force of the silica gel.
Production of outer mold:
The generally used method and material is to surround the mold with rubber sheets or wooden boards, and fill the mold cabinet with plaster. The other method is to use resin brushing. After applying a layer of resin, a layer of glass is pasted. Fiber cloth, brush and paste, repeat two or three layers to complete the outer mold of the mold.
The operation method of filling mold or pouring mold:
Pouring molds or perfusion molds are used for relatively smooth or simple products. There is no mold line to save labor and time, that is, to copy the product or model you want to copy, pour the vacuumed silica gel directly onto the product, and wait for the silica gel to dry and form After that, take out the product. (Note: The perfusion mold is usually made of soft silicone, so that it is easier to demold and will not damage the product in the silicone mold).
Vacuum Casting Tolerances
The accuracy of the master pattern, the geometry of the part, and the type of casting material used all affect the final dimensions of vacuum cast parts. A shrinkage rate of 0.15 % is to be expected in general.
Urethane casting is a cost-effective way to create rigid or rubber-like plastic prototypes and end-use parts. It makes a limited number of castings with silicone molds rather than expensive metal tooling. It’s comparable to injection moulding, except the tooling is more flexible and soft. As a result, urethane casting is more cost effective than injection molding, particularly in low-volume manufacturing.