2026-01-15
Pulp molding mold design plays a decisive role in the performance, quality, and manufacturability of molded pulp products. Unlike conventional plastic tooling, pulp molding mold design is not limited to mechanical structure alone. Product properties are jointly influenced by raw materials, additives, fillers, and forming processes, making mold design a comprehensive engineering discipline.
Due to the characteristics of pulp molding forming technology, a molded pulp product typically has one uniform wall thickness. Functional performance must therefore be achieved through structural geometry rather than thickness variation.
Mold cavities improve product elasticity and cushioning performance
Reinforcing ribs enhance strength and stiffness without increasing material consumption
Corrugated or honeycomb structures are recommended for large flat surfaces requiring high load-bearing capacity
These structural features are essential elements of functional pulp molding mold design.
In the early forming stage, the product exists as a wet pulp preform. During dewatering and drying, dimensional changes occur due to uneven shrinkage.
Shrinkage varies at different locations on the same plane
Uneven shrinkage leads to warping or twisting
Structural balancing through geometry is the only effective adjustment method
Such designs are known as process-oriented structures and are critical for dimensional stability.
A proper draft angle ensures smooth demolding:
Too small: surface damage and tearing
Too large: reduced dimensional accuracy
Balanced draft angles are fundamental to high-quality pulp molding tooling.
Wall thickness affects strength, efficiency, and energy consumption.
Vacuum forming: 0.5–6 mm
Compression molding: 3–20 mm
Excessive thickness increases drying energy use and defect risk.
Rounded transitions improve:
Mold manufacturing
Pulp flow during forming
Stress distribution
Demolding reliability
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