The molding process for pulp molded products differs significantly from that of rubber and plastic products in the mold cavity. Pulp molded products are formed using a slurry containing approximately 1% fiber in a water solution. During forming, most of the water must be removed, requiring molds to be meshed. The molding process involves the slurry depositing a certain thickness onto a mesh mold, necessitating formation on the surface of a single convex or concave mesh mold. As the product forms, it also acts as a filtering process, with thicker sections decreasing filtration performance and forming speed. Thus, regardless of the complexity of the product shape, the thickness of pulp molded products uniformly grows synchronously. The wall thickness of these products primarily depends on the pressure difference inside and outside the mesh mold, namely the vacuum degree during molding, which is significantly restricted in vacuum filtration molding, typically ranging from 300 to 650 Pa.
After molding, pulp molded products are damp paper molds with a moisture content of 70% to 75%. Initially formed damp paper molds adhere to the mesh mold with low wet strength. They must be transferred to a corresponding convex or concave mold cavity and pressed to move by utilizing a pressure difference, then transferred to drying equipment for final drying.
These specific aspects of the pulp molding process greatly influence the structural and mold design of pulp molded products. Designers must comprehensively consider these influencing factors to achieve ideal structural and mold designs for pulp molded products.
The mold design for pulp molded products must meet structural requirements while considering both usage and forming process conditions, aligning with requirements for mold design and manufacturing. Therefore, before designing pulp molding molds, thorough analysis and research of pulp molded product structures are necessary to ensure economic feasibility, technical feasibility, and harmonization between mold and product designs.
