Loading and Pulping
Raw Material: Waste paper is utilized in the production line, mainly consisting of old newspapers, cartons, and packaging boxes. This raw material is supplied to the hydraulic pulper through a belt conveyor or even pulp is fed to the machine by hand.
Pulping: The pulper has water and the raw material. The high-speed impellers within the pulper paper mills and separates the individual plant fibers to produce a rough pulp. As this is occurring, the forming pulp is being screened and any larger impurities consisting of plastic and sand are removed.
Pulping and Coloring
To get a concentrated raw pulp ready for molding, a significant amount of water is added to a mixing tank to get the proper dilution.
In accordance with the specific formulation, the correct additional components (like wetting agents that keep the trays from softening due to moisture) and food-safe colors (for trays that need to be colored) are incorporated. All aspects of the procedure are governed by a PLC which maintains the balanced concentration and composition of pulp for every batch-this means the basis of consistent product quality is established.
Refining and Storage
The prepared thin pulp is then stored in a slurry tank for later use and continuously stirred at a low speed to prevent fiber settling.
Phase 2: Forming and Initial Dewatering
This is the core and most technically demanding stage of the entire process.
Vacuum Adsorption Forming
The forming station features a forming mold (called a "former"), which resembles the negative shape of an egg tray and is covered with small holes for suction and drainage.
The former descends and immerses itself in the pulp within the slurry tank.
At the same time, a vacuum pump is activated, creating negative pressure inside the mold. Water from the pulp is rapidly drawn away, while the plant fibers are evenly adsorbed onto the mold surface, forming a wet, embryonic egg tray.
Technical Key:
Our mold design and vacuum system ensure uniform thickness and dense fiber distribution for each egg tray, providing the load-bearing strength required for the final product.
Transfer (Mold Transfer)
The wet egg tray blank is firmly adsorbed onto the forming mold. At this point, another transfer mold (upper mold) precisely matching the egg tray's shape descends and closes with the forming mold (lower mold).
The transfer mold is connected to an air circuit. After closing, the transfer mold is purged with air while the forming mold releases the vacuum and switches to a light puffing process. This coordinated suction and puffing process ensures the wet egg tray blank is completely transferred to the transfer mold.
This delicate step ensures that the soft and fragile wet blank is transferred intact.
Phase 3: Drying and Shaping
The egg trays coming from the forming line have a moisture content of up to 70%–75% and require drying.
Mechanical Pre-Dehydration
Before entering the drying line, the transfer mold carries the egg tray blank over a mechanical squeeze roller, which gently presses the bottom of the tray to remove some moisture and improve drying efficiency.
Drying Methods (Configured According to Customer Needs)
A. Gas/Oil/Biomass Drying Line:
This is the most popular and efficient method. The transfer mold carrying the egg trays moves through a long, multi-layered drying tunnel. A hot air furnace generates clean, hot air, which is blown into the tunnel by a fan, drying the trays evenly and efficiently. Temperature and drying time can be precisely controlled.
B. Electric Heating Drying Line:
Suitable for areas with abundant electricity or strict environmental protection requirements. The principle is similar, but operating costs are higher.
C. Natural Drying:
We can also provide a matching drying rack as a low-cost supplementary option. However, this method is highly susceptible to weather conditions, offers low efficiency, and is unsuitable for large-scale production.
Demolding
After the egg trays complete one or more rotations in the drying line and reach the required dryness (approximately 10%–13%), they return to the demolding station.
At this stage, the transfer mold generates a strong airflow or aligns the trays with a moving conveyor belt to blow or push the dried and shaped trays onto the conveyor belt for the next stage.
Phase 4: Finished Product Processing and Packaging
Hot Pressing and Shaping
After the drying process, customers looking for an even more refined, polished look can request the addition of a hot press. Dried egg trays run through a hot press where they are subjected to high temperature, high pressure, and are magnetically placed under a smoothing mold. This process quickens the flattening to create an instant surface smoothing/finish, as well as improves surface strength of the trays.
Counting and Stacking
Egg trays on the conveyor belt are automatically counted by a photoelectric counter. An automatic stacker or robot then neatly stacks the trays into predetermined quantities (e.g., stacks of 50).
Packaging and Palletizing
The stacked egg trays are fed into a baler, where they are strapped with plastic film or paper tape to form neatly packaged units. Finally, these units are stacked onto pallets by an automatic palletizer for easy forklift transport and storage.
