How Molded Pulp Packaging Is Made — The Complete Manufacturing Process

Design & 3D Modeling

It starts with your product dimensions and requirements. Our design team creates a 3D model accounting for:

• Product fit — Exact cavity dimensions with 0.5-1.0mm clearance
• Stacking strength — Wall angles and rib placement for load-bearing
• Embossing zones — Logo and texture placement on non-structural surfaces
• Draft angles — 3-5° draft for clean mold release

Mold Fabrication

The 3D model is converted to CNC toolpaths. Aluminum molds are machined with ±0.2mm precision:

• Forming mold — The male/female pair that shapes wet pulp
• Transfer mold — Moves the formed part to the hot press
• Hot press mold — Heated mold that dries and compresses the fiber
• Trimming die — Cuts excess material from edges

For embossed packaging, the relief (logo/texture) is machined directly into the forming mold surface. This is what enables our 8mm relief depth — deeper than standard 1-3mm industry norms.

Timeline: 7-15 days for standard molds, 15-25 days for complex multi-cavity or deep-relief molds.

Pulp Preparation

Raw material (recycled paper, bagasse, bamboo, or wood pulp) is mixed with water in a pulper to create a slurry — approximately 96% water, 4% fiber.

• Material selection — Bagasse for food packaging (heat-resistant), wood pulp for premium finish, recycled paper for standard industrial packaging
• Additives — Food-grade water repellent (for food-contact), natural colorants, strength enhancers
• Consistency control — Fiber concentration monitored continuously for uniform density

Wet Forming

The forming mold is submerged in the pulp slurry. Vacuum suction draws fiber onto the mold surface, building up a uniform layer. This is where the magic happens:

• Vacuum pressure — Controlled to achieve target wall thickness (1.5-3.0mm)
• Dwell time — 3-8 seconds per cycle depending on thickness and geometry
• Fiber orientation — Random fiber distribution creates isotropic strength (equal in all directions)
• Surface quality — Screen marks on the back side are normal; the mold side is smooth

Hot Press Drying

The wet-formed part (still ~70% water) is transferred to a heated press at 180-220°C. The hot press:

• Removes moisture — Reduces water content to < 8%
• Compresses fiber — Increases density and surface smoothness
• Sets the shape — Heat and pressure lock in dimensional accuracy
• Cycle time — 15-60 seconds per part depending on thickness

Trimming & Quality Control

Dried parts go through finishing and multi-point inspection:

• Edge trimming — Hydraulic trimming die cuts excess material to spec
• Visual inspection — Every batch checked for surface defects, color consistency, embossing clarity
• Dimensional check — Random sampling with calipers, ±0.5mm tolerance verified
• Drop test — 1.2m free-fall drop test for protective packaging
• Moisture content — Verified < 8% before packing

Packing & Shipping

Finished parts are packed and prepared for export:

• Bulk packing — Stacked in corrugated cartons, 200-500 pcs per carton
• Palletizing — Standard export pallets, stretch-wrapped
• Container loading — 20ft container holds ~80,000-120,000 units (depending on part size)
• Shipping documents — Commercial invoice, packing list, Fumigation cert, Form A (GSP)