About Vacuum Casting For Mass-Produced Prototyping

2023-01-04 17:46:00
Silicone has good simulation, strength and extremely low shrinkage. It is simple and easy to make elastic molds with this material, without special technology and equipment, and it only takes a few hours to make at room temperature. Silicone molds can withstand repeated use and rough operations, can maintain the precision tolerances of prototypes and mass-produced products, and can directly process parts with complex shapes, eliminating the need for milling and grinding processes, and it is very easy to demould, greatly shortening the production time. The trial production cycle of the product, and the modification of the mold is also very convenient. In addition, due to the good flexibility and elasticity of the silicone mold, for parts with complex structures, fine patterns, no demoulding slope or inverted demoulding slope and deep grooves, the parts can be taken out directly after pouring. , which is its uniqueness compared to other moulds. 
Rapid prototype surface treatment
The prototype made by the RP rapid prototyping method generally has steps or gaps between its laminated sections, which need to be polished, anti-seepage and strengthened to improve the surface smoothness, moisture resistance and heat resistance of the prototype. Only when the surface of the prototype is smooth enough can the surface roughness of the silicone mold produced be guaranteed, thereby ensuring that the copied product has a high surface quality and is easy to take out from the silicone mold.

Make the frame and fix the prototype

Design the shape and size of the pouring frame according to the geometric size of the prototype and the requirements for the use of the silicone mold. The size of the frame should be moderate. Before fixing the rapid prototype, it is necessary to determine the position of the parting surface and the gate. The determination of the parting surface and the position of the gate is very important. It directly affects whether the pouring rapid prototype can be demoulded smoothly and the pouring quality of the rapid prototype is good. After the parting surface and the gate are selected and processed, the prototype is fixed in the frame.

Silica gel metering, mixing and vacuum defoaming

The amount of silica gel should be accurately measured according to the size of the molded frame and the density of silica gel. Add the measured silica gel into an appropriate proportion of hardener, stir well and then vacuum defoam. The defoaming time should be mastered according to the degree of vacuum achieved.

Silicone casting and curing

After vacuum degassing, the silicone mixture is poured into the fixed prototype frame. In the pouring process, certain skills should be mastered. After the silica gel is poured, in order to ensure that the cavity is completely filled, vacuum defoaming is performed again. The purpose of degassing is to extract the gas mixed into the silica gel during the pouring process and the gas enclosed in the prototype cavity. The degassing time should be appropriately longer than the degassing time before pouring. The specific time should be based on the selected silica gel. The operational time of the material depends on the size of the prototype. After defoaming, the silicone mold can be cured by itself or by heating. Heat hardening can shorten the hardening time.

Remove the mold frame, cut the mold with a knife and take out the prototype of the prototype

After the silicone mold is hardened, the mold frame can be dismantled and the sprue rod etc. can be removed. Refer to the mark on the parting surface of the prototype to cut the mold with a knife, take out the prototype, and clean the cavity of the silicone mold as necessary, then the silicone mold can be used to manufacture resin or plastic products in a vacuum state.

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