Rectangular Cavity Compression Molding Die

Rectangular cavity compression molding die is a heavy-duty tool used in compression molding of SMC (sheet molding compound), BMC (bulk molding compound), and GRP glassfiber reinforced plastic. The die produces flat rectangular parts such as equipment panels, inspection covers, and electrical enclosure doors.

Die Construction

The die consists of a polished rectangular cavity plate mounted in a robust steel die set. The upper half contains the male punch, and the lower half contains the female cavity. Guide pins and bushings ensure accurate alignment. Heating cartridges are drilled through the die plates to maintain the cure temperature, typically 150–170 °C for SMC.

Compression Molding Process

A pre-weighed charge of SMC or BMC is placed in the heated cavity. The press ram descends, and the material flows under pressure (typically 100–200 bar) to fill the cavity. The resin cures under heat and pressure for a few minutes, then the mold opens and the finished part is ejected.

Key Features

• Mirror-polished cavity surface for smooth, paintable parts.

• Heating cartridges for uniform temperature control.

• Guide pin alignment for consistent wall thickness.

• Ejector pins for automatic part removal.

• Side action for undercut features where required.

Applications

Rectangular compression molds produce electrical enclosure panels, access covers, machine guards, bathtub and shower surrounds, and decorative FRP panels. The process is ideal for large, thin-walled parts with high surface finish requirements.

Conclusion

The rectangular cavity compression molding die is a fundamental tool for SMC/BMC production. Proper temperature control and polished cavity surfaces are essential for dimensionally accurate, high-gloss parts.