The hot pressing mold usually uses a hydraulic press, and the cavity and core are fixed on the upper and lower pressing plates of the machine. Once the material is placed in the open mold, the machine is turned off, the mold is heated, and then the pressure forces the material to flow through the entire mold.
In the above process, the materials put into the mold are usually composite materials such as SMC, BMC, and GMT. So we always refer to this type of compression mold as SMC mold, BMC mold, GMT mold.
There are certain differences between SMC, BMC and GMT materials.
SMC (sheet molding compound) is a fiber-reinforced thermosetting material, usually used for large parts that require higher strength.
BMC (Bulk Molding Compound) is characterized by its soft texture and short fibers.
GMT (Glass Mat Reinforced Thermoplastic) can also be recycled.
Only the GMT material needs to be preheated.
The SMC mold requires a heating channel, not a cooling channel in the injection mold. The normal heating system is steam, oil, electricity or high-pressure water.
The working temperature of SMC mold is usually 140 degrees to 160 degrees. When designing the temperature system, the mold surface must be kept within a close temperature range. A mold with a uniform temperature will be easier to fill and produce parts with less warpage, reduced dimensional stability, and uniform surface appearance.
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Post time: Nov-04-2021