Molded Pulp Mold Venting & Drainage Hole Design: Forming Quality Hides in the Hole Layout

Molded pulp is wet-formed: slurry is dewatered by vacuum filtration on the mold to take shape. The layout of venting and drainage holes directly affects wall-thickness uniformity, forming speed, and product strength—a critical detail in mold design.

Scenario: Three Challenges in Hole-Layout Design

Improper mold hole layout brings three problems:

Pain Points

• Uneven venting-hole layout causes uneven wall thickness—locally too thin or too thick—and unstable strength;
• Too few drainage holes slow dewatering and lengthen the forming cycle, capping throughput;
• Improper hole size leaves visible hole marks on the finished surface, hurting appearance.

Solution: Three Key Points in Hole-Layout Design

Mold venting and drainage hole design has three key points:

1. Uniform hole distribution. Distribute holes evenly according to cavity stress and dewatering needs so slurry deposits consistently and wall thickness stays uniform.

2. Tiered hole diameter. Use larger holes in deep cavities and corners to speed drainage, and fine holes on flat surfaces to keep them smooth—matched by tier.

3. Hole shape matched to demolding. Match hole shape (round/slotted) to the demolding direction to avoid the finished part hanging on holes or being scratched.

Result: Both Forming Quality and Efficiency Rise

With the hole layout done right, wall thickness stays uniform, forming is stable, dewatering efficiency improves, and surface hole marks are controlled for more consistent product quality.