Overview of Pulp Molding Production Process and Equipment

1.1 Classification of Pulp Molding Processes

Pulp molding (also called plant fiber molding) is a processing method that uses plant fiber pulp to manufacture various molded products through specialized molds. There are currently two main production processes in common use: dry pressing and wet pressing.

Dry Pressing Process

Process: Pulp liquid (with additives) → Adsorption molding → Wet blank → Tunnel drying (out-of-mold drying) → Heat pressing and shaping

Applications: Mainly for low-end egg trays, fruit trays, and simple industrial packaging products

Wet Pressing Process

Process: Pulp liquid (with additives) → Adsorption molding → Wet blank → Transfer to heat-press mold for drying and shaping (in-mold drying) → Finished product

Applications: Primarily for food packaging and high-end industrial packaging. In recent years, wet pressing has been widely applied to various pulp molded products.

This chapter uses a factory producing plant fiber tableware with wet pressing technology as an example to introduce the wet pressing pulp molding production process, equipment selection, and factory design.

1.2 Introduction to Wet Pressing Pulp Molding Equipment

Wet pressing pulp molding equipment refers to production equipment that uses pulp as raw material to form wet blanks through adsorption molding, then transfers them to heat-press molds for pressurized drying and shaping, and finally removes the finished products from the molds and completes edge trimming.

Equipment Classification:

• By forming method: Slurry injection type, pulp fishing type, flip type
• By heat-press station quantity: Single station, dual station, multi-station
• By automation level: Manual, semi-automatic, fully automatic
• By edge trimming method: Automatic trimming, manual trimming, no trimming
• By functionality: Single-function machines, multi-function machines

Equipment Types by Automation Level:

1. Fully automatic pulp molding-forming-pressing-trimming integrated machines

• Automatically completes: Pulp adsorption forming → Wet blank transfer → Heat pressing and drying → Trimming → Finished product stacking

2. Semi-automatic pulp molding-forming-pressing-trimming machines

• Automatically completes: Pulp adsorption forming → Drying and shaping
• Manual operation: Trimming process

3. Manual pulp molding-forming-pressing-trimming machines

• Manual operation: Wet blank transfer → Heat pressing and drying → Trimming

Equipment Characteristics:

Semi-automatic/manual equipment:

• Low production efficiency, large footprint
• Requires additional safety devices
• Needs separate sterilization for food packaging

Fully automatic equipment:

• Higher efficiency, larger output
• Equipped with complete safety devices meeting industry standards
• No separate sterilization required for food packaging

a. Single-function automatic machines: Only suitable for specific products (e.g., ordinary tableware), limited to products with height <70mm and simple large-angle designs

b. Multi-function fully automatic forming-pressing-trimming integrated machines: High precision, suitable for high-end tableware, precision small-angle industrial packaging, and hot drink lids

1.3 Advantages of Multi-function Fully Automatic Forming-Pressing-Trimming Integrated Machines

Pulp molding production equipment is the main equipment in pulp molding factories.

• Multi-functionality: Suitable for eco-friendly tableware, inverted hot drink lids, precision small-angle industrial packaging, premium egg trays, and fruit/vegetable trays
• Integrated design: Combines automatic forming, drying, shaping, and trimming in compact structure with small footprint
• High space efficiency: 2-3 times higher production capacity than conventional equipment in same space, significantly reducing construction costs and management expenses
• Safety: Fully enclosed safety protection devices ensure safe production
• Compliance: Designed to meet European and American safety standards (automatic stop when doors open during operation)
• Automation: High production capacity with low energy consumption and labor costs
• Efficiency: 30% lower direct production costs compared to conventional equipment
• Stability: Smooth and stable operation
• Technology: Incorporates advanced international and domestic manufacturing methods and machine structures
• Ergonomics: Clean and comfortable working environment for operators