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Egg Tray Production Line Process and Working Principle

Egg Tray Machine and Egg Tray Production Line Process

1. Raw materials

The main raw materials for producing molded pulp egg trays are newspapers, cultural paper, cardboard, paper boxes, and corner waste paper from paper mills, cardboard factories, or printing plants. The raw material resources are abundant, and the prices are low. Importantly, it achieves the comprehensive utilization of waste materials, contributing to certain social value.

2. Pulping

The primary raw material for making molded pulp egg trays, waste paper, is fed into a hydraulic pulper, where it is broken down into pulp fibers under the shear and friction forces of water flow. The pulp fibers enter the pulp storage tank. To enhance the appearance and cleanliness of the product, the pulp in the storage tank is screened to remove impurities (such as film pieces, hemp ropes, coarse debris) from the fiber pulp. Subsequently, the pulp is diluted to a certain concentration and finally pumped into the pulp box of the molding machine.

3. Molding

When the molding mold above the molding machine’s pulp box is completely immersed in the pulp, the pulp is adsorbed and gathered on the mold surface under the suction of vacuum at the back of the molding mold. Due to the unique surface filtration and hollow structure of the molding mold, the pulp fibers in the gathered material adhere to the mold’s surface, while water is drawn away. The fiber layer adhering to the mold’s surface is approximately 2.5mm thick, forming the wet blank of the egg tray product, which contains about 70% water.

4. Drying

The wet blanks of the egg tray products need to be sent to the drying line (temperature 120-200°C) for dehydration and drying. After drying, the finished egg trays are ready for packaging and storage.

Egg Tray Machine: Understanding the Working Principle

The working principle of the molded pulp (egg tray) forming machine involves the use of vacuum filtration technology for shaping. In other words, the forming mold, immersed in low concentration pulp (around 1% concentration), relies on vacuum filtration to create negative pressure inside the mold cavity. The fibers in the pulp, under the influence of vacuum filtration, uniformly adhere to the surface of the forming mold’s mesh, while a significant amount of water is carried away during vacuum filtration. When the desired thickness of the product is achieved, the forming mold is removed from the pulp for dehydration. After dehydration, compressed air is used to transfer the product from the forming mold to a transfer mold, and then it is moved to the drying process.

The basic working procedure is as follows: Molded pulp absorption of pulp – Vacuum dehydration – Product transfer – Drying-Packing.

Note: All processes are physical processes, and the production process involves the reuse of water in a closed loop. There is no wastewater discharge since, after forming, the egg trays contain 70% water, and during the drying process, the water is evaporated, eliminating the need for wastewater discharge.

The working principle of the molded pulp (egg tray) forming machine involves the use of vacuum filtration technology for shaping. In other words, the forming mold, immersed in low concentration pulp (around 1% concentration), relies on vacuum filtration to create negative pressure inside the mold cavity. The fibers in the pulp, under the influence of vacuum filtration, uniformly adhere to the surface of the forming mold’s mesh, while a significant amount of water is carried away during vacuum filtration. When the desired thickness of the product is achieved, the forming mold is removed from the pulp for dehydration. After dehydration, compressed air is used to transfer the product from the forming mold to a transfer mold, and then it is moved to the drying process.

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